Using proper approved testing methods I have found the Chinese isolators from some brands are as good as UK brands. It’s mainly to the people do not talk down the connections or they think the links are optional.
To blame the DC isolator for a fire begs the question as to exactly why it has failed - unapproved switch design or incorrect selection / installation. This recommendation to delete an isolator seems strange to me. Perhaps solar panels should not be installed in a sunny location? Then everything will be within ratings 😂
It is not as odd a request as you think. BS7671 still needs to be complied with, and it says a means of isolation needs to be provided. What the insurance companies are talking about is removing of or not installing a separate DC isolation switch, and under the regs you don't need one if there is one integrated into the inverter. So they are actually talking about the removal of a redundant component.
Doesnt matter if you switch ac or dc, the point is, there could be reasons why you want to switch the dc side, and if you do have to choose the right equipment for that dc voltage, and be able to switch max current in and out, choosing the wrong one could cause fire, just like choosing the wrong one to switch the dc side.. op is right.
@deang5622 it's redundant until a lighting strike blows out the inverter and you have to replace it. The isolator is definetly more convenient when you are trying to mash the cables into a dc converter or charger.
@@MikeyisNinja Never heard of lightning conductors? You don't use or rely on a DC isolator to protect your installation from lightning strikes. That's where lightning conductors and spark gaps, surge protective devices come into play. An isolation switch is NOT a surge protective device.
Horrendous to hear about the tragic loss of life, especially someone so young. Nobody should be exposed to danger when going to work that can result in injury and worse death. Thoughts with the family. Got to say I agree with the comments here. DC isolators in true form separate to electrical equipment aka an inverter are essential. It allows safe working practices. Its time industry faced up to the real problem of poor installation. From the hooks to the isolators. I have written to the authors of that document discussed to find out who exactly was involved in its production and if they would like to help remove those poor installation practices rather than essential system components. Thanks for sharing!
It's more that the design of the PV install is fundamentally faulty, you should never let PV panels that are exposed to full sunlight just float, they need to be grounded or run into a loadbank when not connected to a load. It's a known issue that PV installers don't want to deal with, because then you probably need a seperate grounding system just for the PV to let it discharge the energy into the earth, and you need a DPDT switch to isolate them, and even then, the solar panels remain under liver current.
@@Mr424242424242424242 What is the danger posed by a floating solar panel?
Před 7 měsíci
@@Mr424242424242424242 wouldn't the option be to cover the panels so that the power generated is diminished or reduced be a partly solution? It's just a thought.
A tragic story about Matthew Camble. The strong reminder that if we feel that it’s not safe doing something, then it probably isn’t. As an electrician who has deviated away from the mainstream for sometime, I look forward to watching your videos to keep me abreast of the industry changes. Thank you 👍
DC isolator installation depends on country regulation. In my country if the DC cable goes inside the attic then within 5 meter from the entry point a DC isolator must be installed and operated remotely. The idea is that is should be controlled by the main/firefighter switch to isolate the panels from DC cables that are running inside the house to avoid electronic shock. There is only few high quality 1000V DC rated products are available. There is always a cheap alternative from a well known online reseller, but I would not install those to my house.
1) Poor connection causes overheating of the terminal, breakdown, extensive sustained arcing until combustion of adjacent materials. 2) failure of the isolator itself causes sustained arcing until combustion of adjacent materials. Look up what a 500VDC arc is like, nothing like AC.
1)Poor contact resistance, 2) Metal parts not rated for the current 3) Plastic parts not rated for the temperature 4) Excessive operation of the switch when under load, the arcing causing premature erosion of the contacts leading to increased contact resistance. The arcs produced by switching DC are a much bigger problem to dissipate than for AC.
I fit ferules on all the PV connections to get the best connection but if the equipment’s failing that’s worrying because these big PV companies always blame the installer
So, who is going to trust technology over a switch? In the same way, a 3phase Spd that takes the supply straight down to earth without any over current protection. Those of us that have been around long enough will know, if something can go wrong it will. So, when it goes wrong, will your insurance pay out? To me at least, when it comes to electrical safety, give me a good old fashioned isolator any day. When it's off, it's off end of story.
Do not disconnect under load for 500V DC ? There must be 1000's of solar PV installations just in the UK. I bet 99% of them have a DC isolator since the regs does mention it - ours does.
I use a polarised 500v breaker and double insulate the solar cable connetion point, cut the ferrule to size, but to cut power my inverter has an intigrated isolator switch. At max current & volts the temperature of the breaker connection points is not more than 2 degrees above ambient. Personaly I think testing thermals during max loading is a must.
if the dc isolator on the inverter is ok as an isolator I see no problem useing that only. however if the inverter is monted inside the building I would want a Dc isolator installed outside the house incase there is a Fire for whatever reason so the fire brigade don´t have to go inside the bulding to look for the isolator switch.
In many places this is actually required in order to be code compliant, regardless of whether or not the inverter has a built in disconnect. Every Firefighter and Lineman know what a disconnect looks like, they don't necessarily know if a particular inverter has one built in., Where I am we are actually required to have rapid shutdown at the panel level; for all solar roof installations.
In Australia, the DC isolators usually corrode, and catch on fire, besides they offer no overload/fault protection and are pretty much useless. Problem is that the Australian code says that they must be fitted, but they at least should not be up on the roof, where the weather causes them to fail, and instead be sited in a proper weatherproof cabinet.
So the problem really is bad installation of the isolator or an unsuitable type. Excess heat with those hot summers you have and then not waterproofed if it rains. Everything is watertight in UK for external use. Fireman's switch a good example. Regulation requirements and never seen a faulty one in all my years. We get rough weather here and survive.
@@kennethausten It's usually the cheapest nastiest isolator that the Electrician can get their hands on, then installing it in a crap location. It's not the rain that causes issues initially but the sun here - even UV stabilised plastics cop a flogging over a few years and slowly warp or degrade until they allow water in. Installing the isolator in a location like near the inverter on the south side of the house for example (equivalent to the north side for you) alleviates these issues, but the amount you see stuck up on the roof is amazing.
Talk about a "U turn" on DC isolators, first they insist you fit them, despite the Inverter manufacturers stating they are unnecessary - you just couldn't make it up.
Yeah seems it was all the rage 10 years ago even though my SE inverter has one built in - suspect the external isolator isn’t even explicitly rated for DC - fortunately the SE optimisers can deal with dropping any HV DC down to safe levels
It's fascinating to see how regulations and recommendations around the world lurch around like this. Personally I reckon you always want an external way to remove supply from a device. Everything has a built in on/off switch yet we still have means to isolate wiring in standard AC wiring. That shouldn't change with PV. If anything given the sort of voltages that are permitted it should be mandatory. Not sure on the max voltage over there but many places are now moving to allow 1kV or higher even in domestic. Use a non-rubbish properly spec'd DC isolator and don't put it in a situation where it is going to be weather damaged.
I don’t understand. Neither of the failures highlighted related to DC isolators. How do the ones fitted inside inverters differ from those selected for use outside inverters. Simply stating “there is a problem with them so don’t fit them” doesn’t seem to make any sense to me. Surely a review of the selection and choice of the isolators would be more appropriate.
If they are incorrectly wired, incorrectly labled, or manufactured badly they don't work properly and the arc causes heat. I think someone has a CZcams video of one on fire and explains the issue.
I would be interested to know the mode of failure of the dc isolators on PV installations. Having worked in industry with extensive dc systems- 55V, 110V, 240V, and 485V, I have never experienced any of the dc switchgear to fail. Indeed, I regard isolators as essential, so is this just a knee-jerk response to incidents or has proper investigation identified the fault? Why would an isolator within the control panel be any safer than an external one? By the way, an endorsement from Greta Thunberg would not tempt me to buy anything, even with triple Nectar points!
It was definitely a bad connection, probably on the AC side. I've seen a video of a fire with a Victron system caused by that. Victron's connectors are very weird, so a DIYer misjudged how much copper to expose. Also they discourage the use of ferrules, because on boats the shaking makes that weird stuff come loose.
@@squeaky_honda i disagree but i realize this is a hotly debated topic. ferrules are widely recomended on boats for the very reason of preventing loose connections. compressed wires will loosen up soon after install due to the wires slowly compressing, not to mention repeated heating and cooling. ferrules work perfectly in victron gear. i just installed 6awg ferrules in a victron charger yesterday no problem. a bigger issue might be that these connections never get re-checked soon after the initial install when they will likely have loosened up, especially if its a diy'r who doesnt realize or its a professional install and no one comes back to check.
@@joesmith1142 Google for "Ferrules are not to be used with Victron MPPTs", quotes included. You'll find an official statement from Victron that bans ferrules and why. I've seen it in some of their docs, too. I favour ferrules, so this stood out to me.
As a firefighter and an electrician, picture this: We're responding to a fire involving a solar panel fire and they removed the isolators on the solar panels so we're gunna yank mc4s until they're all isolated? yea I'm sticking to a remote disconnection device that isolates panel to panel connections my house is powered by a hybrid solar system (it can act as a grid tied system and an off grid system) for 5 years now and nothing happened no fires nothing. I even built the batteries myself sometimes it's when people get curious and touch what shouldn't be touched like the solar installation I did to a residential structure I told them not to tamper the settings and even let them sign a waiver that if there are signs of tampering, I have the right to waive my involvement in an incident involved, lo and behold they got curious they touched the settings and permanently damaged the lead acid batteries by charging it with the wrong voltage and current causing it to bloat and explode
No. You just go to the inverter and perform one of two actions: 1. Turn the isolation switch in the inverter 2. Pull the connectors on the cables to the inverter. The difficulty for the fire brigade is educating every fireman the different topologies: With or without a separate isolation switch. And then there is time spent searching trying to identify whether a separate isolation switch is in use.
@@deang5622 you probably don't know how PV systems work, when a solar panel fails it can cause a problem if it's a series circuit hence the use of an internal bypass diode. now if you isolate the inverter does it isolate the solar panels connected in series? That's also why an inline PV fuse is used and also rapid shutdown devices should be implemented, 500v solar arrays are an extreme pain in the ass if they have problems. I am a registered tradesman and i probably know how to install PV systems
@@dragonfireproductions790 I know more about solar panels than you could ever know in your life time mate. I have formally studied them. As for diodes...I have solved many problems with Ebers Moll. Don't be so condescending as you might just be talking to someone that knows far more about this than you do. I was making PN junctions and other semiconductor devices probably before you were born. If you are an electrician, even if you have specialised in PV installation, then I guarantee you you don't know as much about this as I do.
@@deang5622 but you probably don't know the most recent safety devices used in solar systems nowadays, look up rapid shutdown devices used in solar power plants it individually isolates all of the solar panels in a system making it easier to prevent a domino effect
@@dragonfireproductions790 Let me explain it to you. If you are trying to isolate a PV circuit, it does NOT matter where you put the isolator, except it is better to put it in the positive line from the panels. In that way you are removing any lethally high voltage. If you break the circuit, current stops flowing. IET regs say that if the inverter contains an integral isolation switch, you don't need a separate isolation switch. This is a fact and it is not up for debate. And that inverter integrated isolation switch is as far away from the panel from a circuit point of view, as possible. Clearly there is no obligation to place the means of isolation close to the panels. The reason for this is because in an electrical circuit, you can break that circuit anywhere and current will cease flowing. So what is being discussed in the regs about isolation is about the isolation from the panels to the inverter. They are NOT talking about isolating individual panels and trying to protect against short circuit faults among the panels! Talking about series or parallel connected panels is a complete irrelevance. The series configuration results in two cables going to the inverter. If you need an isolation switch then you put one in in one of those cables. In a parallel configuration, there is a decision to be made as to how those pairs of conductors from each panel or sets of panels are routed to the inverter. Let's suppose there are 2 panels in parallel, that's 4 wires. If all 4 are routed to the inverter then you will need two separate isolation switches. If those two pairs of two conductors are commoned together so that only two conductors are routed to the inverter then you only need a single isolator. The problem that might arise in a PV installation is when an electrician post initial verification is wanting to make changes to the configuration of panels and the isolation switch is integrated down in the inverter, or the individual strings of panels do not have their own isolation means, that potentially dangerously high voltages may be present across multiple panels. You are not likely to be electrocuted by touching bare wires or terminations from a single panel - unless it's a f..g big panel. Just think it through, for crying out loud.
Great content but I think you buried the lead on your first article on "DC Isolators"....................! Literally on the next paragraph down is the statement; "The Code applies to all stages of a project....... **The recommendations in this guide are NOT INTENDED for single residence dwellings (detached or connected), or to roof-integrated PV Panel systems" That's a very definitive distinction.
This was the law until recently in Australia. (ROOFTOP isolators) It caused HEAPS of fires! Finally the requirement of rooftop isolators has been dropped.
I never understood why roof top isolators were made mandatory over isolators that were mounted by the Inverter and better protected from weather,just doesn, t seem to be a safer way apart from being able to isolate at the cable run at the panel string,surely they are and have been more prone to failure.My Daughters installation from 5 years ago has both panels and on the wall external to inverter the Fronius also has it's own dc isolator switch.
I would suggest that perhaps many isolators are not capable of clearly breaking the on line voltage at the rated current. A line of panels can easily get up to 600v (shouldn't but they do), if installers are not allowing for this and not wiring the internal switches in series then all hell is going to occur. With DC the trick is to make the gap on the contacts as big as possible, and that means series contacts, and each contact must be capable of carrying full current. I would suggest a factor of at least 1.3 safety. Panel array = 20Amps at 450v(theoretical max), then an Isolator made to break full load current at full voltage of around 25 or 30 Amps at 585-600v DC. Often that means wiring 2 sets of contacts in series in both legs. Many 'isolators' are not meant for ON-load breaking but often only capable of OFF-load disconnection, it you shut the inverter down, then isolate the panels (with lock) to work on them. I also suggest that the Isolator is placed in a floor accessible position. Roof is no good.
SolarEdge line voltage is fixed 750V the production is switched on when the line voltage practically around 930-950V without load then it is regulated to the fixed 750V.
@@gabor.nadudvari depends on the system, many inverters work on a max of 600v, some are 1000v but thats pushing every connector on the solar array. best you go check your maximums on your kit, if you are getting 900-950, then I suggest thats your problem.
I use specially designed Kraus and Naimer 1000 volt DC isolators. There are 2 lots of 3 poles in series in these isolators. Rule 1 never open the switch when it has a load on it. Started in the trade in 1974 and I might just know a bit more than some insurance Johnny.
With out a DC isolator you would have to make the PV connection in the night I can’t see how a dc isolator of the correct specifications can cause a fire
MC4 connectors are protected, just don't plug/unplug it on load. The guys on the roof are plugging and unplugging them when installing anyway so there is no extra new hazard.
Excessive contact wear possibly by switching too many times under load. Shouldn't happen to a good quality, suitably designed switch, but I bet it does.
Back in 2010 I got a warning from my solar installer to never disconnect the solar during the day. I now live offgrid with a completely new installation by persons I trust. They told me the same: There is a thick isolator: disconnect during the night, or extreme emergency. Victron MPPT's don't disconnect, but you can turn them "off": they will let the solar float, and hence it is safe to disconnect. The disconnect is for a 202V max measured setup.
Are you sure about that? Checked the latest regulations? I think you'll find they do not have to be on the roof anymore, not least because of the ironic fire hazard. You now have the option of putting them elsewhere and simply having an indicated disconnection point on the array showing a place where a (MC4) connector is to be found that will disconnect the array from the downstream wiring. Despite the reason being given being for firemen to disconnect the array that was the opinion of one man and not the general recommendation of the firemen themselves. Firemen aren't stupid and don't want to get up on a roof of a building that is on fire and likely structurally compromised then falling through and being injured or dieing. Put simply, the roof top isolator did nothing for improving safety and actually resulted in several fires in Australia.
If your pulling DC strings out of an inverter under load, you are dancing with the DC Arc Angels! Its not going to be nice for you in the right conditions. I'm an advocate for THE CORRECT TYPE of isolators.
I am not sure I agree with RISCA, do they know something the IET do not? If there is no DC isolator then how do you isolate when you need to run tests on the panels and most importantly. In a few years time when you need to replace the inverter do they think it will be done at night so there is no DC voltage/Current? (I am assuming Domestic here) Very important point to consider is that not all Solar PV panels have an optimiser which detect no inverter and drop the output to 1volt. If they think the MC4s or the DC isolators are the cause they need to investigate if they are upto the job. are the MC4s on the panel compatiable with the installers MC4s connectors and crimp tool? Not all brands play together nicely. If they are upto the job was the install done properly by a competent person. Local isolation is in BS7671 for a reason and that reason is to save lives.
You need to go back and listen to what Joe said. The IET regs on this say that a means of isolation *_IS_* required. There is no doubt about this. The question is around how that isolation is to be provided. Whether it be provided by a separate dedicated DC isolation switch or whether the integrated isolation switch inside the inverter is to be used, if there is one.
No load no problem. A trained and competent person would be able to work safely on a solar installation. Followed up with suitable and sufficient RAMS usually does the job.@sergiofernandez3725
In many countries a DC isolator is required by law, and it is required to be mounted on a non flammable surface. Personally I think all electronics related solar panels including batteries should be mounted in a fire proof room, and ideally in a separate part of the house or in a separate building that are non flammable.
likewise EV's, should not be allowed to be parked inside any garage that us integral to the house. But battery installations etc, should be outside, and have some fire detection/alert systems built in for an early warning
@@TheJensss Safer than hot fires inside though. People need to accept the blatant reality that lithium ion batteries are dangerous. Even more so large ones/quantities of them
@@blow0me Agree, that is why people should build a separate part of the house out of a non -combustible materials such as concrete, leca, bricks, etc. for batteries and solar components
@@efixx The UK government should pass a law that clearly states that anyone who installs solar systems on the roof must make the roof fire proofe there is no other way to be hundred percent safe.
@@democracyforallthere is … skilled workers ! To many acclaimed electricians who… A- can’t make an mc4 off correctly B- can’t ferrule crimp a flexible cable in the DC isolator C- use a torque driver on the connections or even panels That’s why there’s so many loose connections …. I’ve done a stack of solar and they do some amazing neat work … and then the connections are hooooorifix! (See what I did there😅)
@@jerome8670 CORRECT so that is one of those reason the roof needs to made fire proof by law. the solar panel itself inside also is not perfect it catches fire in some cases even if you did it all correct so a law is needed.
I use a snubber circuit (a resistor and condenser in series) across the contacts on the switch which stops the small dc arc across the switch when opening and closing the contacts. (it's old school man)
So, those news media reports are ... ridiculously lacking in any detail or knowledge. A fire investigator can absolutely tell the difference between a fire caused by a solar panel, an isolator on the roof (a huge huge mistake), or a charge controller fire (typically situated inside or in a sealed enclosure). DC isolators exposed to the elements should be avoided ALWAYS. Now I know there was a time when I think parts of Australia tried to require them up on the roof for fire fighters, but manual isolators just shouldn't be up on the roof or ever exposed to the weather, even if they have IP65 or IP67 sealing. IMHO, I would avoid as much junk up on the roof as possible. The combiner box, for example, should not be up on the roof either. Backhaul the individual strings down to an easily accessible place for the combiner box. Why? * Manual DC isolators are usually NOT spring loaded and cannot quickly break ARCs. This causes carbon build-up on the contacts. Particularly at the voltages solar panels operate at. * Manual DC isolators CANNOT be switched under load, but most people do it anyway. This causes carbon build-up on the contacts. * Manual DC isolators DO NOT HAVE A THERMAL TRIP, meaning that they will not automatically trip on the most common failure case for manual DC isolators. * The contacts are extremely vulnerable to corrosion and oxidation due to exposure to the weather. This causes additional resistance. The carbon build-up and resistance ultimately creates a thermal event. The plastic casing will melt and depending on how it is mounted eventually catch something on fire. Having this up on the roof where it is difficult to inspect regularly makes it doubly dangerous. And that is why manual DC isolators should never be installed anywhere where they are exposed to the elements, or anywhere "just because it might seem like a good idea", by installers or anyone else. Use proper UNPOLARIZED double-pole DC breakers for your disconnects. The only DC isolator you ever see should be the one integrated into the solar inverter (if there is one). And even that might not be the best idea in the world. Proper unpolarized double-pole DC breakers rated for the solar voltages involved should be used pretty much wherever you want a disconnect. They should be in properly sealed boxes or inside and NEVER exposed to the elements. - Why unpolarized? Most people, even electricians, tend to wire polarized DC breakers incorrectly and in solar applications it is often impossible to wire them correctly because the power might flow both ways, and the short condition might also come from either side and thus also flow both ways. Unpolarized DC breakers typically do not have the two magnets on either side of the arc gap to direct the arc (polarized DC breakers typically have such magnets). - Why 2-pole. To properly isolate the subsystems you want to isolate both the positive and the negative. - Why DC breakers instead of manual disconnects? DC breakers have thermal trips, spring loaded disconnection, and ARC extinguishers internally. The typical failure case for a properly installed DC breaker is to trip rather than catch fire. - Automatically trips on over-current and instantly trips on a short, and can be tested as such. - But be warned that IMPROPER installation of a DC breaker (improper voltage range for voltages involved, improper use of a polarized DC breaker instead of using an unpolarized breaker) can also lead to a fire. -- Also, the wiring for a solar string MUST ALWAYS BE FUSED, in addition to any breakers. This is typically done inside the combiner box (and you should have a combiner box even if you aren't paralleling any strings). The fuse MUST be a 10x38mm 1000V DC ceramic fuse for solar applications, period, and the amperage should be as specified by the panel label. Each string must be separately fused (the combiner box typically has a fuse position for each string being combined, including if only one string). Some people argue about breakers and fuses on the same string, and think the breaker's function is somehow rendered useless by the fuse. It is not. That breakers and fuses serve two different functions. The fuse is the primary protection against a short. The breaker is primarily there as an ARC-safe disconnect, and also serves as a backup safety device against a panel short. Plus having a breaker at the combiner box AND ALSO just prior to the charge controller provides protection for wiring faults that backfeed through the charge controller from the battery. "Popping the fuse" IS NOT AN ARC-SAFE disconnect. Its a last resort if it didn't blow on its own and the breaker didn't trip either, but you don't pop a solar fuse as your "disconnect". You can only pull the fuse safely after turning off the breaker. -Matt
Solar strings are class 5 cables and should have an ultrasonic weld or a bootlace ferrule as a minimum. I've never seen any signs of heat damage with the above but too many without. Also, adhereeing to MI for torque settings and use a descent tool will certainly help to reduce lose terminations and heat.
How is an isolator causing fires,some inverter manufacturers recommended or require separate DC isolators, despite their equipment having a built in isolator, so what happens then. As usual, things like this happen and there's no proper guidance we have several bodies giving conflicting information and the only losers are the installers and customers.
You can but they need to be the tandem type breaks with a mosfet switch and isolates with a electromagnetic contactor. These are also built into several types of charge regulators as well.❤
I missed the arguments against DC Isolators - nothing found! So - what is this all about? We all know: PV can put an additional fire risk to your house. I try to avoid as many components as possible and just install the really necessary. An isolator switch is optional, and if properly produced and installed there is no additional risk imho. When contacts are bad - of course you have a risk.
What is the difference between ac and dc isolators . Both have make and break contacts and should be rated at appropriate capacity. Normally there would be arc quenching filters to avoid contact arcing. As these isolators are only operated on a very low duty cycle it seems that the installation may be suspect.
Just had a really fun time trying to pry off some old brittle mc4's under an old SMA inverter. Voc=800V - really would have appreciated a DC isolator!!!
Just cut the cable …. Job done! The problem with DC isolators is that they causing more problems from loose connections arcing and burning out as opposed to isolating for maintenance! There’s not enough electricians who can do a ferrule crimp and connect correctly … they twist the flex or it splays out of the connections … I’ve seen some horrific connections on some amazing looking work!
@@jerome8670 I do get it. I do think that during an MCS inspection they should have a proper look at the actual installation work rather than spending so long on the poxy quality management system that nobody cares about.
@@freddiewithers9617 the MCS ….. feels like it’s just aiming completely in the wrong direction! Way too bureaucratic for me…. Like a chicken and an egg scenario …you can’t do solar with out being MCS buuut you can’t be MCS without knowing solar 😂
Can someone explain how a DC isolator might cause a fire? Or how a fault that caused a fire might not have done so had there been no DC isolator installed? As Joe said there's a hefty line up of expertise behind this advice, so it should be taken seriously. But even so what is the _exact_ problem?
Use of the wrong type of isolator or improperly installed would be my take, not that the isolator itself is the problem. Firefighters also don't like it if the solar panels can't be disconnected and might refrain from putting out a fire and instead go for letting the construction burn.
Australia has had its fair share of solar house fires, many caused by faults in the DC isolators. Regulations and DC isolator designs have changed over time. A lot were caused by condesation forming inside the isolator which led to arcing. The design has changed a few times.
Given that it is frequently going to be difficult to establish the exact cause of an electrical fire in a PV installation, surely there should be equal emphasis on both: a) correct, accredited system design and installation, *and* b) comprehensive consequential damage insurance provided by the installer (backed up by the equipment supplier) ...anything less is going to result in a bunch of companies squabbling over who's to blame (as with Victron).
Victron kit is pretty good kit. Charge controlers and inverters are suposed to be mounted on fire proof boards anyway. Very sad to hear but glad everyone is alive but the fault could have been a multitude of things.
I see no reason to banish DC isolators seeing as the inbuilt DC isolators are exactly the same mechanism, seems ridiculous to me. Also how are you supposed to safely test short circuit currents without an additional DC isolator. (If you don’t have the pv specific test equipment)
Most inverter isolators are non lockable. DC isolators are double pole with air gap but some have screw terminals could this be the weak link. Maybe the connection should be mc4 as we see on Chinese made isolators
I am not sure I understand what the DC isolators have to do with the fires described, which seem unrelated. I am also not sure I understand how a well-designed and properly-installed DC isolator could cause a fire.
there are manufactures of breakers with magnets and arc chutes to quench an arc for high DC interruption. They are designed to open under load and quench the arc. Please note they are polarity sensitive as the polarity determines the direction of the arc blow in the magnetic field. Polarity must be observed to blow the arc into the arc chute instead of away from it. Many breakers for DC have low voltage ratings due to the difficulty in quenching an arc. For panel arrays, ensure the breaker is able to quench the open circuit voltage under load. Other DC disconnect devices have multiple series contacts to break the arc. Large gap knife switches work well as the gap when open is more distance than the current can mantain an arc. Use the type often used for inductive loads such as for a heat pump disconnect switch. Double break and an open distance greater than 1 inch is good to stop the arc. The distance is important the same way cutting the cable broke the arc. You need a large device with the ability to make a large gap when open. For over current protection, use the sand filled multi-element fuse for at least the rated voltage. The sand falls into the arc to quench it.
Surely in the event that so equipment is catching on fire it should be placing something like a metallic enclosure more as a common sensing and a regulatory thing so you can have adequate ventilation but it will contain a fire
The selected words of the week are fungus and gingerbread . And as always thank you very much. It's really fun to see the electricity news, I appreciate it very much.
MCS install fail if you don't fit an isolator separate from the inverter so ill wait until there is an update telling me otherwise. Insurance company 'experts' Isolators don't cause fires unless you use an AC instead of a DC and vice versa.
Thank you for this valuable information. When I was installing my panels last year, I already didn't put any DC isolator on the roof. All MC4 connectors are secured and ON the roof tiles, which are made of concrete. Electrical engineers are well aware, that the main problem in electrical circuits are contacts and switches. High voltage DC is the worst, if arcing starts, it will burn until the contacts are separated at least an inch or so. I have MC4 HV fuses on positive and negative side and a HV DC fuses before the inverter. Solar cables are laid separated about 2 inches, in case of rodents would eat thru insulation. I think this will do. Better safe then sorry.
@@mrtechie6810 You are absolutely right. Since I have two fuses on each side of the string and another double DC fuse at the inverter side I'm hoping that in case of "mild lightning", I mean not direct lightning strike, fuses together with over voltage varistors would save my inverter. Each string gives 18Ap and fuses are 25A, so solar will never trigger them by itself. It's just my over engineering with a bit of hope in mind.
I searched for a DC isolator switch when installing my first solar system I could only find 160 volt DC switch Knowing the danger of isolating DC I wired my solar in serie and parallel for a maksim of 126 volt Since then the new inverters mppt range is 120 to 500 volt or higher That present a problem So the only way to isolate is to remove the load first Switch everything off before isolating the pv supply DC voltage and current flow cause a significant arc that is difficult to break and will burn the breakers Any carbon caused by the arc in the breaker switch area will cause current flow and eventually a fire 45 Jr ago I observed in training the switch used to isolate 400 volt DC The switch ( knife) had a separate blade parallel with the main blade that was attached to the main blade with a spring When opening the main blade, the auxiliary blade remained connected and pulling out until the spring can cause the final current break at high speed Faster than you can move the switch with your hand That was used on 400 volt DC system's Since then semiconductors scr igbt MOSFETs etc, made the need for isolating DC obsolete Now we isolate on the ac system side Solar pv isolating switch of the load current down to zero isolate.
My best bet would be some of THESE words: fungus, Joe, square, circle, gingerbread, Mail, air fryer. Teacher A Trade, flame, Icon, cigar, few frights, Swiss Army knife, Boy Scouts, Ultra, kit for explosive areas, Grizzly Adams, and torque calibrated arm Thank you :-)
My solar PV system was installed in 2015, and has DC & AC isolators. So far the only failure has been the AC isolator (a couple of years after installation).
Handy info. I would be interested to know how old the PV systems were that caught fire. My oldest system has been in for 13 years now and it's not caught fire yet. Maybe I should start checking the DC isolators with a thermal camera as a precaution?
The problem is people picking the wrong DC isolator and using them in the wrong configuration. Installers cutting costs by taking the link out and halving the current rating then putting two strings through the same DC isolator. DC isolators are also excellent for any maintenance or repair works, what if you cannot depend on the built in DC isolator? What if an MC4 has been damaged and you need to replace it? Poor workmanship and purchasing inferior products is the problem here not DC isolators.
Instead of an isolator, could a switch to ground be as effective? ( Or between + and - of the solar leads) This way the contacts are not in use until that time of need. Could be installed as a single use emergency device to ensure solar voltage is zero.
There should be some regulations to minimize the fire risks: as few components between charge controller and solar panels as possible, minimize wiring between each component and all component rated with safety in mind (700V array => rated for 700V + 20% => 900V). Why you need to connect all solar panels in series? 30V per panel and 120V to 240V should be enough to build an array to get the cables down. Look what a cable isolation fault on a 700V system looks like and you never put the + and - cables in the same pipe.
I do not understand why UK electricians don’t explore micro inverters more. Easy to commission and much safer due to isolation and dealing with smaller DC voltage.
I guess you should’ve put all of your solar equipment on cement board, so that even if the switch burns up, it can’t catch anything on fire. Same with your batteries, inverters, solar charge controllers. Keep everything at least 20 feet from your house so that if it does catch on fire, it doesn’t burn your home down too. Stop putting solar panels on your roof. That should be common sense. Get some RF connected smoke detectors. Then buy some CO2 fire extinguishers to keep around.
yet, I had my bypassed and the electrician found the installers did a dodgy job as he worked on the bypass. I only have the isolators next to the inverter now, even though they did a dodgy job there too.
Solar panels are current sources and sholud be handled like those. Never open the circuits in current sources , they have to be short- circuit. solar inverters use this method to inactivate the solar power. input. And you cannot protect current sources with fuses. Cuurent sorces got a high internal resistace (Ri) , high open loop voltage so exact the other way round than voltage sources like the electical mains. When install solar panels, never place connectors , taps or splittings underneath the roof /attic. Install wires in one piece from the panel to the inverter/charger. Use high cross sectional wire gauges, not because lower loss, but rather of the mechanical sturdiness. Install connection boxes in a fireproof environment e.g on a brick walls. Do not store flammable items in the vicinity of inverters and solar installations. Battery banks shoud not be installs inside of homes / flats. The best is a separate shelter apart from the house.
If the Victron system had no DC isolator switch, why mention it here? Are there no example cases where the DC isolator switch actually caused the issue?
This morning I tested a mc4 connector to see if it would burn result they support fire and do not self extinguish There for a damage mc4 plug in /out under load is a fire 🔥 risk
they no why but if there is no isolator it could happen many soler System are install by in experience technician high voltage dc is not the same as ac and many early System were in install by unqualified technicians
Perhaps, with all the news of house fires allegedly being caused by photo voltaic systems, the creators of a training program might think of a different name than "Green Spark"
Will the party telling you not to install isolators assist you if you have to replace an inverter? Are they going to come out and safely isolated because there are not many ways you can do that?
Well that's an interesting concept. We allow companies to manufacture isolators that arnt fit for purpose and fail dangerously, then change the rules so they sent required anymore 🤷🏻♂️. In industry we often have multiple isolation points on motor circuits nobody ever said "you are introducing more potential failure points" what a cop out. 44 years since I started, back then if your isolator was rated at 32a 500v, that was it's all day rating 24/7/365. Would have been good for twice that short term. At the same time we have idiots complaining they can't fit solar batteries in lofts anymore.
Question. i rent a unit with a garage down stairs with only light circuit. probably has no earth (at least not at switch when i checked ). I want a power point supply to mess with hobby electronics only in shed. Can i take power off the light or is there a chargeable device that i can plug into mains in the unit and carry it downstairs to shed as a temporary power supply ? Thats assuming there is no earth at the light fitting when i get around to checking it.
As an electrical engineer I would just like to ask all the Sparky's on this channel how much temperature they think a small arc welder with IGBT's (so D.C.) generates. Then think of why they call it an arc welder😂
Sounds more like a "DON'T INSTALL CRAPPY CHINESE OFFBRAND DC ISOLATORS WHICH COST 1/50th OF A SAME RATING PRODUCT FROM A KNOWN BRAND"
Using proper approved testing methods I have found the Chinese isolators from some brands are as good as UK brands. It’s mainly to the people do not talk down the connections or they think the links are optional.
To blame the DC isolator for a fire begs the question as to exactly why it has failed - unapproved switch design or incorrect selection / installation. This recommendation to delete an isolator seems strange to me. Perhaps solar panels should not be installed in a sunny location? Then everything will be within ratings 😂
It is not as odd a request as you think.
BS7671 still needs to be complied with, and it says a means of isolation needs to be provided.
What the insurance companies are talking about is removing of or not installing a separate DC isolation switch, and under the regs you don't need one if there is one integrated into the inverter.
So they are actually talking about the removal of a redundant component.
Doesnt matter if you switch ac or dc, the point is, there could be reasons why you want to switch the dc side, and if you do have to choose the right equipment for that dc voltage, and be able to switch max current in and out, choosing the wrong one could cause fire, just like choosing the wrong one to switch the dc side.. op is right.
@@deang5622it is an odd request, you for sure need to be able to switch you dc input off on your inverter for reasons..
@deang5622 it's redundant until a lighting strike blows out the inverter and you have to replace it. The isolator is definetly more convenient when you are trying to mash the cables into a dc converter or charger.
@@MikeyisNinja Never heard of lightning conductors?
You don't use or rely on a DC isolator to protect your installation from lightning strikes.
That's where lightning conductors and spark gaps, surge protective devices come into play. An isolation switch is NOT a surge protective device.
Horrendous to hear about the tragic loss of life, especially someone so young. Nobody should be exposed to danger when going to work that can result in injury and worse death. Thoughts with the family.
Got to say I agree with the comments here. DC isolators in true form separate to electrical equipment aka an inverter are essential. It allows safe working practices. Its time industry faced up to the real problem of poor installation. From the hooks to the isolators.
I have written to the authors of that document discussed to find out who exactly was involved in its production and if they would like to help remove those poor installation practices rather than essential system components. Thanks for sharing!
A fire caused by a faulty solar charge controller is nothing to do with a DC isolation switch, if a separate isolation switch is installed.
Sound like lithium battery fire to me said it was off-grid likely DIY battery.
It's more that the design of the PV install is fundamentally faulty, you should never let PV panels that are exposed to full sunlight just float, they need to be grounded or run into a loadbank when not connected to a load. It's a known issue that PV installers don't want to deal with, because then you probably need a seperate grounding system just for the PV to let it discharge the energy into the earth, and you need a DPDT switch to isolate them, and even then, the solar panels remain under liver current.
@@Mr424242424242424242 The PV grounding is meant to help incase of lightning strike.
@@Mr424242424242424242 What is the danger posed by a floating solar panel?
@@Mr424242424242424242 wouldn't the option be to cover the panels so that the power generated is diminished or reduced be a partly solution?
It's just a thought.
A tragic story about Matthew Camble. The strong reminder that if we feel that it’s not safe doing something, then it probably isn’t. As an electrician who has deviated away from the mainstream for sometime, I look forward to watching your videos to keep me abreast of the industry changes. Thank you 👍
DC isolator installation depends on country regulation. In my country if the DC cable goes inside the attic then within 5 meter from the entry point a DC isolator must be installed and operated remotely. The idea is that is should be controlled by the main/firefighter switch to isolate the panels from DC cables that are running inside the house to avoid electronic shock. There is only few high quality 1000V DC rated products are available. There is always a cheap alternative from a well known online reseller, but I would not install those to my house.
So how exactly does a separate DC isolator cause a fire?
1) Poor connection causes overheating of the terminal, breakdown, extensive sustained arcing until combustion of adjacent materials.
2) failure of the isolator itself causes sustained arcing until combustion of adjacent materials.
Look up what a 500VDC arc is like, nothing like AC.
1)Poor contact resistance,
2) Metal parts not rated for the current
3) Plastic parts not rated for the temperature
4) Excessive operation of the switch when under load, the arcing causing premature erosion of the contacts leading to increased contact resistance.
The arcs produced by switching DC are a much bigger problem to dissipate than for AC.
Crap terminations. Links removed etc.
@@edc1569 And are they connected in series to be running at 500v ?
@@blow0me that's how solar works generally yes, seen up to 1kv on a solar array. I think we should be using old style MEM Excel isolators on it
I _think_ the report means that:
*1)* *_poor quality_* DC isolators;
*2)* cables with *no* bootlace ferrules;
Should *not* be fitted.
I fit ferules on all the PV connections to get the best connection but if the equipment’s failing that’s worrying because these big PV companies always blame the installer
I think main reasons are 1) poor quality components 2) poor quality work
So, who is going to trust technology over a switch? In the same way, a 3phase Spd that takes the supply straight down to earth without any over current protection.
Those of us that have been around long enough will know, if something can go wrong it will.
So, when it goes wrong, will your insurance pay out? To me at least, when it comes to electrical safety, give me a good old fashioned isolator any day. When it's off, it's off end of story.
Where's the explanation about how a DC isolator could cause a fire?
See my post. I explained how
right on bro this is a 'kin infomercial waste of space clickbait shite
Do not disconnect under load for 500V DC ?
There must be 1000's of solar PV installations just in the UK. I bet 99% of them have a DC isolator since the regs does mention it - ours does.
I use a polarised 500v breaker and double insulate the solar cable connetion point, cut the ferrule to size, but to cut power my inverter has an intigrated isolator switch. At max current & volts the temperature of the breaker connection points is not more than 2 degrees above ambient. Personaly I think testing thermals during max loading is a must.
if the dc isolator on the inverter is ok as an isolator I see no problem useing that only. however if the inverter is monted inside the building I would want a Dc isolator installed outside the house incase there is a Fire for whatever reason so the fire brigade don´t have to go inside the bulding to look for the isolator switch.
Thanks for your viewpoint. 👍
How do you do that for a domestic dwelling (to isolate the mains supply)?
Isn't the fault likely on the roof, or in the attic, doesn't this extra new outside unit and connections just add more risk than it takes away.
In many places this is actually required in order to be code compliant, regardless of whether or not the inverter has a built in disconnect. Every Firefighter and Lineman know what a disconnect looks like, they don't necessarily know if a particular inverter has one built in., Where I am we are actually required to have rapid shutdown at the panel level; for all solar roof installations.
In Australia, the DC isolators usually corrode, and catch on fire, besides they offer no overload/fault protection and are pretty much useless. Problem is that the Australian code says that they must be fitted, but they at least should not be up on the roof, where the weather causes them to fail, and instead be sited in a proper weatherproof cabinet.
How about using tinned marine cable? And why isnt wire corrosion a problem with other circuits in similar locations?
The pvc boxes containing the isolators always allow rain in , Sometimes the cable entry points are not done properly -- not water tight etc etc
So the problem really is bad installation of the isolator or an unsuitable type. Excess heat with those hot summers you have and then not waterproofed if it rains. Everything is watertight in UK for external use. Fireman's switch a good example. Regulation requirements and never seen a faulty one in all my years. We get rough weather here and survive.
@@kennethausten It's usually the cheapest nastiest isolator that the Electrician can get their hands on, then installing it in a crap location. It's not the rain that causes issues initially but the sun here - even UV stabilised plastics cop a flogging over a few years and slowly warp or degrade until they allow water in. Installing the isolator in a location like near the inverter on the south side of the house for example (equivalent to the north side for you) alleviates these issues, but the amount you see stuck up on the roof is amazing.
Talk about a "U turn" on DC isolators, first they insist you fit them, despite the Inverter manufacturers stating they are unnecessary - you just couldn't make it up.
Yeah seems it was all the rage 10 years ago even though my SE inverter has one built in - suspect the external isolator isn’t even explicitly rated for DC - fortunately the SE optimisers can deal with dropping any HV DC down to safe levels
Yeah, I'm about to give up.
This is the insurers.. when were they expert electrical practitioners?
@@MikeGleesonazelectrics You will find that the insurance company’s drive most of the changes to all trades
@@bill2960 could be, doesn't mean they know best tho, just to avoid payouts I guess!
It's fascinating to see how regulations and recommendations around the world lurch around like this. Personally I reckon you always want an external way to remove supply from a device. Everything has a built in on/off switch yet we still have means to isolate wiring in standard AC wiring. That shouldn't change with PV. If anything given the sort of voltages that are permitted it should be mandatory. Not sure on the max voltage over there but many places are now moving to allow 1kV or higher even in domestic.
Use a non-rubbish properly spec'd DC isolator and don't put it in a situation where it is going to be weather damaged.
I don’t understand. Neither of the failures highlighted related to DC isolators. How do the ones fitted inside inverters differ from those selected for use outside inverters. Simply stating “there is a problem with them so don’t fit them” doesn’t seem to make any sense to me. Surely a review of the selection and choice of the isolators would be more appropriate.
If they are incorrectly wired, incorrectly labled, or manufactured badly they don't work properly and the arc causes heat. I think someone has a CZcams video of one on fire and explains the issue.
I would be interested to know the mode of failure of the dc isolators on PV installations. Having worked in industry with extensive dc systems- 55V, 110V, 240V, and 485V, I have never experienced any of the dc switchgear to fail. Indeed, I regard isolators as essential, so is this just a knee-jerk response to incidents or has proper investigation identified the fault? Why would an isolator within the control panel be any safer than an external one?
By the way, an endorsement from Greta Thunberg would not tempt me to buy anything, even with triple Nectar points!
Usually - water ingress, especially via the conduit to the roof. Otherwise improper screw terminal tightening.
@@benharris4436drip loop?
Victron doesn't make crap, they have no chance of blaming victronenergy.
100% it was dodgy connection or similar. no chance it was the victron, that shit is solid.
It was definitely a bad connection, probably on the AC side. I've seen a video of a fire with a Victron system caused by that. Victron's connectors are very weird, so a DIYer misjudged how much copper to expose. Also they discourage the use of ferrules, because on boats the shaking makes that weird stuff come loose.
@@squeaky_honda i disagree but i realize this is a hotly debated topic. ferrules are widely recomended on boats for the very reason of preventing loose connections. compressed wires will loosen up soon after install due to the wires slowly compressing, not to mention repeated heating and cooling. ferrules work perfectly in victron gear. i just installed 6awg ferrules in a victron charger yesterday no problem. a bigger issue might be that these connections never get re-checked soon after the initial install when they will likely have loosened up, especially if its a diy'r who doesnt realize or its a professional install and no one comes back to check.
@@joesmith1142 Google for "Ferrules are not to be used with Victron MPPTs", quotes included. You'll find an official statement from Victron that bans ferrules and why. I've seen it in some of their docs, too. I favour ferrules, so this stood out to me.
No matter what manufacture it is a bad one sooner or later will slip through. That being said I have Victron in my camper because of their reputation.
Many countries (e.g. Germany) actually mandate DC isolation switches for solar installation for fire reasons.
As a firefighter and an electrician, picture this:
We're responding to a fire involving a solar panel fire and they removed the isolators on the solar panels so we're gunna yank mc4s until they're all isolated? yea I'm sticking to a remote disconnection device that isolates panel to panel connections
my house is powered by a hybrid solar system (it can act as a grid tied system and an off grid system) for 5 years now and nothing happened no fires nothing. I even built the batteries myself sometimes it's when people get curious and touch what shouldn't be touched like the solar installation I did to a residential structure I told them not to tamper the settings and even let them sign a waiver that if there are signs of tampering, I have the right to waive my involvement in an incident involved, lo and behold they got curious they touched the settings and permanently damaged the lead acid batteries by charging it with the wrong voltage and current causing it to bloat and explode
No. You just go to the inverter and perform one of two actions:
1. Turn the isolation switch in the inverter
2. Pull the connectors on the cables to the inverter.
The difficulty for the fire brigade is educating every fireman the different topologies:
With or without a separate isolation switch.
And then there is time spent searching trying to identify whether a separate isolation switch is in use.
@@deang5622 you probably don't know how PV systems work, when a solar panel fails it can cause a problem if it's a series circuit hence the use of an internal bypass diode. now if you isolate the inverter does it isolate the solar panels connected in series? That's also why an inline PV fuse is used and also rapid shutdown devices should be implemented, 500v solar arrays are an extreme pain in the ass if they have problems. I am a registered tradesman and i probably know how to install PV systems
@@dragonfireproductions790 I know more about solar panels than you could ever know in your life time mate. I have formally studied them.
As for diodes...I have solved many problems with Ebers Moll.
Don't be so condescending as you might just be talking to someone that knows far more about this than you do.
I was making PN junctions and other semiconductor devices probably before you were born.
If you are an electrician, even if you have specialised in PV installation, then I guarantee you you don't know as much about this as I do.
@@deang5622 but you probably don't know the most recent safety devices used in solar systems nowadays, look up rapid shutdown devices used in solar power plants it individually isolates all of the solar panels in a system making it easier to prevent a domino effect
@@dragonfireproductions790 Let me explain it to you.
If you are trying to isolate a PV circuit, it does NOT matter where you put the isolator, except it is better to put it in the positive line from the panels. In that way you are removing any lethally high voltage.
If you break the circuit, current stops flowing.
IET regs say that if the inverter contains an integral isolation switch, you don't need a separate isolation switch.
This is a fact and it is not up for debate.
And that inverter integrated isolation switch is as far away from the panel from a circuit point of view, as possible.
Clearly there is no obligation to place the means of isolation close to the panels.
The reason for this is because in an electrical circuit, you can break that circuit anywhere and current will cease flowing.
So what is being discussed in the regs about isolation is about the isolation from the panels to the inverter. They are NOT talking about isolating individual panels and trying to protect against short circuit faults among the panels!
Talking about series or parallel connected panels is a complete irrelevance.
The series configuration results in two cables going to the inverter.
If you need an isolation switch then you put one in in one of those cables.
In a parallel configuration, there is a decision to be made as to how those pairs of conductors from each panel or sets of panels are routed to the inverter.
Let's suppose there are 2 panels in parallel, that's 4 wires. If all 4 are routed to the inverter then you will need two separate isolation switches.
If those two pairs of two conductors are commoned together so that only two conductors are routed to the inverter then you only need a single isolator.
The problem that might arise in a PV installation is when an electrician post initial verification is wanting to make changes to the configuration of panels and the isolation switch is integrated down in the inverter, or the individual strings of panels do not have their own isolation means, that potentially dangerously high voltages may be present across multiple panels. You are not likely to be electrocuted by touching bare wires or terminations from a single panel - unless it's a f..g big panel.
Just think it through, for crying out loud.
Great content but I think you buried the lead on your first article on "DC Isolators"....................!
Literally on the next paragraph down is the statement;
"The Code applies to all stages of a project....... **The recommendations in this guide are NOT INTENDED for single residence dwellings (detached or connected), or to roof-integrated PV Panel systems"
That's a very definitive distinction.
This was the law until recently in Australia. (ROOFTOP isolators)
It caused HEAPS of fires! Finally the requirement of rooftop isolators has been dropped.
I never understood why roof top isolators were made mandatory over isolators that were mounted by the Inverter and better protected from weather,just doesn, t seem to be a safer way apart from being able to isolate at the cable run at the panel string,surely they are and have been more prone to failure.My Daughters installation from 5 years ago has both panels and on the wall external to inverter the Fronius also has it's own dc isolator switch.
So why can an isolator, a safety device....cause fires ?
I would suggest that perhaps many isolators are not capable of clearly breaking the on line voltage at the rated current.
A line of panels can easily get up to 600v (shouldn't but they do), if installers are not allowing for this and not wiring the internal switches in series then all hell is going to occur.
With DC the trick is to make the gap on the contacts as big as possible, and that means series contacts, and each contact must be capable of carrying full current.
I would suggest a factor of at least 1.3 safety.
Panel array = 20Amps at 450v(theoretical max), then an Isolator made to break full load current at full voltage of around 25 or 30 Amps at 585-600v DC.
Often that means wiring 2 sets of contacts in series in both legs.
Many 'isolators' are not meant for ON-load breaking but often only capable of OFF-load disconnection, it you shut the inverter down, then isolate the panels (with lock) to work on them.
I also suggest that the Isolator is placed in a floor accessible position. Roof is no good.
SolarEdge line voltage is fixed 750V the production is switched on when the line voltage practically around 930-950V without load then it is regulated to the fixed 750V.
@@gabor.nadudvari depends on the system, many inverters work on a max of 600v, some are 1000v but thats pushing every connector on the solar array.
best you go check your maximums on your kit, if you are getting 900-950, then I suggest thats your problem.
I use specially designed Kraus and Naimer 1000 volt DC isolators. There are 2 lots of 3 poles in series in these isolators. Rule 1 never open the switch when it has a load on it.
Started in the trade in 1974 and I might just know a bit more than some insurance Johnny.
With out a DC isolator you would have to make the PV connection in the night
I can’t see how a dc isolator of the correct specifications can cause a fire
Why ? The isolator on the inverted disconnects the circuit .
MC4 connectors are protected, just don't plug/unplug it on load. The guys on the roof are plugging and unplugging them when installing anyway so there is no extra new hazard.
Excessive contact wear possibly by switching too many times under load.
Shouldn't happen to a good quality, suitably designed switch, but I bet it does.
@@deang5622 You never disconnect an on-load DC circuit by means of an isolator.
@@edc1569People are gonna do it
Back in 2010 I got a warning from my solar installer to never disconnect the solar during the day.
I now live offgrid with a completely new installation by persons I trust. They told me the same: There is a thick isolator: disconnect during the night, or extreme emergency.
Victron MPPT's don't disconnect, but you can turn them "off": they will let the solar float, and hence it is safe to disconnect. The disconnect is for a 202V max measured setup.
A legal requirement in Australia, roof mounted double pole isolator for Firemen to access during a fire.
Are you sure about that? Checked the latest regulations? I think you'll find they do not have to be on the roof anymore, not least because of the ironic fire hazard. You now have the option of putting them elsewhere and simply having an indicated disconnection point on the array showing a place where a (MC4) connector is to be found that will disconnect the array from the downstream wiring.
Despite the reason being given being for firemen to disconnect the array that was the opinion of one man and not the general recommendation of the firemen themselves. Firemen aren't stupid and don't want to get up on a roof of a building that is on fire and likely structurally compromised then falling through and being injured or dieing. Put simply, the roof top isolator did nothing for improving safety and actually resulted in several fires in Australia.
If your pulling DC strings out of an inverter under load, you are dancing with the DC Arc Angels! Its not going to be nice for you in the right conditions. I'm an advocate for THE CORRECT TYPE of isolators.
I am not sure I agree with RISCA, do they know something the IET do not?
If there is no DC isolator then how do you isolate when you need to run tests on the panels and most importantly. In a few years time when you need to replace the inverter do they think it will be done at night so there is no DC voltage/Current? (I am assuming Domestic here)
Very important point to consider is that not all Solar PV panels have an optimiser which detect no inverter and drop the output to 1volt.
If they think the MC4s or the DC isolators are the cause they need to investigate if they are upto the job. are the MC4s on the panel compatiable with the installers MC4s connectors and crimp tool? Not all brands play together nicely. If they are upto the job was the install done properly by a competent person. Local isolation is in BS7671 for a reason and that reason is to save lives.
You need to go back and listen to what Joe said.
The IET regs on this say that a means of isolation *_IS_* required.
There is no doubt about this.
The question is around how that isolation is to be provided. Whether it be provided by a separate dedicated DC isolation switch or whether the integrated isolation switch inside the inverter is to be used, if there is one.
@@deang5622 How would you isolate the solar PV string when you need to work on the inverter or replace the inverter?
No load no problem. A trained and competent person would be able to work safely on a solar installation. Followed up with suitable and sufficient RAMS usually does the job.@sergiofernandez3725
In many countries a DC isolator is required by law, and it is required to be mounted on a non flammable surface.
Personally I think all electronics related solar panels including batteries should be mounted in a fire proof room, and ideally in a separate part of the house or in a separate building that are non flammable.
likewise EV's, should not be allowed to be parked inside any garage that us integral to the house. But battery installations etc, should be outside, and have some fire detection/alert systems built in for an early warning
@@blow0me A separate garage from the house is always smart. However, having batteries outside can be problematic because of low temperatures.
@@TheJensss Safer than hot fires inside though. People need to accept the blatant reality that lithium ion batteries are dangerous. Even more so large ones/quantities of them
@@blow0me Agree, that is why people should build a separate part of the house out of a non -combustible materials such as concrete, leca, bricks, etc. for batteries and solar components
yep. laughing at this guy's video with a bunch of stuff on plywood in the back instead of having concrete board over the plywood lmao
The beard looks good on you , Joe. Thanks for the news. Happy New Year.
Not as good as yours Brian! Cheers mate! 😊
@@efixx The UK government should pass a law that clearly states that anyone who installs solar systems on the roof must make the roof fire proofe there is no other way to be hundred percent safe.
@@democracyforallthere is … skilled workers !
To many acclaimed electricians who…
A- can’t make an mc4 off correctly
B- can’t ferrule crimp a flexible cable in the DC isolator
C- use a torque driver on the connections or even panels
That’s why there’s so many loose connections …. I’ve done a stack of solar and they do some amazing neat work … and then the connections are hooooorifix! (See what I did there😅)
@@jerome8670 CORRECT so that is one of those reason the roof needs to made fire proof by law. the solar panel itself inside also is not perfect it catches fire in some cases even if you did it all correct so a law is needed.
@@democracyforall 💯 the more fire proof items the better
I’ve always wondered why h the there’s no AFDD’s on the DC side also?
I use a snubber circuit (a resistor and condenser in series) across the contacts on the switch which stops the small dc arc across the switch when opening and closing the contacts. (it's old school man)
👍
So, those news media reports are ... ridiculously lacking in any detail or knowledge. A fire investigator can absolutely tell the difference between a fire caused by a solar panel, an isolator on the roof (a huge huge mistake), or a charge controller fire (typically situated inside or in a sealed enclosure).
DC isolators exposed to the elements should be avoided ALWAYS. Now I know there was a time when I think parts of Australia tried to require them up on the roof for fire fighters, but manual isolators just shouldn't be up on the roof or ever exposed to the weather, even if they have IP65 or IP67 sealing.
IMHO, I would avoid as much junk up on the roof as possible. The combiner box, for example, should not be up on the roof either. Backhaul the individual strings down to an easily accessible place for the combiner box.
Why?
* Manual DC isolators are usually NOT spring loaded and cannot quickly break ARCs. This causes carbon build-up on the contacts. Particularly at the voltages solar panels operate at.
* Manual DC isolators CANNOT be switched under load, but most people do it anyway. This causes carbon build-up on the contacts.
* Manual DC isolators DO NOT HAVE A THERMAL TRIP, meaning that they will not automatically trip on the most common failure case for manual DC isolators.
* The contacts are extremely vulnerable to corrosion and oxidation due to exposure to the weather. This causes additional resistance.
The carbon build-up and resistance ultimately creates a thermal event. The plastic casing will melt and depending on how it is mounted eventually catch something on fire. Having this up on the roof where it is difficult to inspect regularly makes it doubly dangerous.
And that is why manual DC isolators should never be installed anywhere where they are exposed to the elements, or anywhere "just because it might seem like a good idea", by installers or anyone else. Use proper UNPOLARIZED double-pole DC breakers for your disconnects. The only DC isolator you ever see should be the one integrated into the solar inverter (if there is one). And even that might not be the best idea in the world.
Proper unpolarized double-pole DC breakers rated for the solar voltages involved should be used pretty much wherever you want a disconnect. They should be in properly sealed boxes or inside and NEVER exposed to the elements.
- Why unpolarized? Most people, even electricians, tend to wire polarized DC breakers incorrectly and in solar applications it is often impossible to wire them correctly because the power might flow both ways, and the short condition might also come from either side and thus also flow both ways. Unpolarized DC breakers typically do not have the two magnets on either side of the arc gap to direct the arc (polarized DC breakers typically have such magnets).
- Why 2-pole. To properly isolate the subsystems you want to isolate both the positive and the negative.
- Why DC breakers instead of manual disconnects? DC breakers have thermal trips, spring loaded disconnection, and ARC extinguishers internally. The typical failure case for a properly installed DC breaker is to trip rather than catch fire.
- Automatically trips on over-current and instantly trips on a short, and can be tested as such.
- But be warned that IMPROPER installation of a DC breaker (improper voltage range for voltages involved, improper use of a polarized DC breaker instead of using an unpolarized breaker) can also lead to a fire.
--
Also, the wiring for a solar string MUST ALWAYS BE FUSED, in addition to any breakers. This is typically done inside the combiner box (and you should have a combiner box even if you aren't paralleling any strings). The fuse MUST be a 10x38mm 1000V DC ceramic fuse for solar applications, period, and the amperage should be as specified by the panel label. Each string must be separately fused (the combiner box typically has a fuse position for each string being combined, including if only one string).
Some people argue about breakers and fuses on the same string, and think the breaker's function is somehow rendered useless by the fuse. It is not. That breakers and fuses serve two different functions. The fuse is the primary protection against a short. The breaker is primarily there as an ARC-safe disconnect, and also serves as a backup safety device against a panel short. Plus having a breaker at the combiner box AND ALSO just prior to the charge controller provides protection for wiring faults that backfeed through the charge controller from the battery.
"Popping the fuse" IS NOT AN ARC-SAFE disconnect. Its a last resort if it didn't blow on its own and the breaker didn't trip either, but you don't pop a solar fuse as your "disconnect". You can only pull the fuse safely after turning off the breaker.
-Matt
Solar strings are class 5 cables and should have an ultrasonic weld or a bootlace ferrule as a minimum. I've never seen any signs of heat damage with the above but too many without. Also, adhereeing to MI for torque settings and use a descent tool will certainly help to reduce lose terminations and heat.
How is an isolator causing fires,some inverter manufacturers recommended or require separate DC isolators, despite their equipment having a built in isolator, so what happens then.
As usual, things like this happen and there's no proper guidance we have several bodies giving conflicting information and the only losers are the installers and customers.
You can but they need to be the tandem type breaks with a mosfet switch and isolates with a electromagnetic contactor. These are also built into several types of charge regulators as well.❤
I missed the arguments against DC Isolators - nothing found! So - what is this all about? We all know: PV can put an additional fire risk to your house. I try to avoid as many components as possible and just install the really necessary. An isolator switch is optional, and if properly produced and installed there is no additional risk imho. When contacts are bad - of course you have a risk.
How would we go about testing on an EICR if we can't isolate the DC comming in?
you can isolate DC underneath the inverter and then carry on with your AC tests at the AC isolator :)
What is the difference between ac and dc isolators . Both have make and break contacts and should be rated at appropriate capacity. Normally there would be arc quenching filters to avoid contact arcing. As these isolators are only operated on a very low duty cycle it seems that the installation may be suspect.
Just had a really fun time trying to pry off some old brittle mc4's under an old SMA inverter. Voc=800V - really would have appreciated a DC isolator!!!
Just cut the cable …. Job done!
The problem with DC isolators is that they causing more problems from loose connections arcing and burning out as opposed to isolating for maintenance!
There’s not enough electricians who can do a ferrule crimp and connect correctly … they twist the flex or it splays out of the connections … I’ve seen some horrific connections on some amazing looking work!
@@jerome8670 I do get it. I do think that during an MCS inspection they should have a proper look at the actual installation work rather than spending so long on the poxy quality management system that nobody cares about.
@@freddiewithers9617 the MCS ….. feels like it’s just aiming completely in the wrong direction!
Way too bureaucratic for me…. Like a chicken and an egg scenario …you can’t do solar with out being MCS buuut you can’t be MCS without knowing solar 😂
Very interesting. .can't see how a dc isolator would have caused the problem. .do the pv installers fit smoke alarms in the attic space .
Can someone explain how a DC isolator might cause a fire? Or how a fault that caused a fire might not have done so had there been no DC isolator installed?
As Joe said there's a hefty line up of expertise behind this advice, so it should be taken seriously. But even so what is the _exact_ problem?
Use of the wrong type of isolator or improperly installed would be my take, not that the isolator itself is the problem.
Firefighters also don't like it if the solar panels can't be disconnected and might refrain from putting out a fire and instead go for letting the construction burn.
Australia has had its fair share of solar house fires, many caused by faults in the DC isolators. Regulations and DC isolator designs have changed over time. A lot were caused by condesation forming inside the isolator which led to arcing. The design has changed a few times.
Given that it is frequently going to be difficult to establish the exact cause of an electrical fire in a PV installation, surely there should be equal emphasis on both:
a) correct, accredited system design and installation, *and*
b) comprehensive consequential damage insurance provided by the installer (backed up by the equipment supplier)
...anything less is going to result in a bunch of companies squabbling over who's to blame (as with Victron).
Victron kit is pretty good kit. Charge controlers and inverters are suposed to be mounted on fire proof boards anyway. Very sad to hear but glad everyone is alive but the fault could have been a multitude of things.
I see no reason to banish DC isolators seeing as the inbuilt DC isolators are exactly the same mechanism, seems ridiculous to me. Also how are you supposed to safely test short circuit currents without an additional DC isolator. (If you don’t have the pv specific test equipment)
Most inverter isolators are non lockable. DC isolators are double pole with air gap but some have screw terminals could this be the weak link. Maybe the connection should be mc4 as we see on Chinese made isolators
What is the point in locking them, the voltage is still present on the MC4 terminals
I am not sure I understand what the DC isolators have to do with the fires described, which seem unrelated. I am also not sure I understand how a well-designed and properly-installed DC isolator could cause a fire.
there are manufactures of breakers with magnets and arc chutes to quench an arc for high DC interruption. They are designed to open under load and quench the arc. Please note they are polarity sensitive as the polarity determines the direction of the arc blow in the magnetic field. Polarity must be observed to blow the arc into the arc chute instead of away from it. Many breakers for DC have low voltage ratings due to the difficulty in quenching an arc. For panel arrays, ensure the breaker is able to quench the open circuit voltage under load. Other DC disconnect devices have multiple series contacts to break the arc.
Large gap knife switches work well as the gap when open is more distance than the current can mantain an arc. Use the type often used for inductive loads such as for a heat pump disconnect switch. Double break and an open distance greater than 1 inch is good to stop the arc. The distance is important the same way cutting the cable broke the arc. You need a large device with the ability to make a large gap when open. For over current protection, use the sand filled multi-element fuse for at least the rated voltage. The sand falls into the arc to quench it.
Surely in the event that so equipment is catching on fire it should be placing something like a metallic enclosure more as a common sensing and a regulatory thing so you can have adequate ventilation but it will contain a fire
It is the low quality , non certified DC isolator that give problem.
The selected words of the week are fungus and gingerbread .
And as always thank you very much.
It's really fun to see the electricity news, I appreciate it very much.
It's the law in Australia, illegal install if there is no isolator.....!!
Question. What is a dc isolator, what does the circuit look like with one installed, how does it start fires?
I like the 'face fuzz' I bet, and I seldom bet, it will look great in a couple more weeks!
MCS install fail if you don't fit an isolator separate from the inverter so ill wait until there is an update telling me otherwise. Insurance company 'experts'
Isolators don't cause fires unless you use an AC instead of a DC and vice versa.
Thank you for this valuable information. When I was installing my panels last year, I already didn't put any DC isolator on the roof. All MC4 connectors are secured and ON the roof tiles, which are made of concrete. Electrical engineers are well aware, that the main problem in electrical circuits are contacts and switches. High voltage DC is the worst, if arcing starts, it will burn until the contacts are separated at least an inch or so. I have MC4 HV fuses on positive and negative side and a HV DC fuses before the inverter. Solar cables are laid separated about 2 inches, in case of rodents would eat thru insulation. I think this will do. Better safe then sorry.
How do fuses help, unless you are connecting panels in parallel? In series, the fault current is already limited by the output of the solar panels!
@@mrtechie6810 You are absolutely right. Since I have two fuses on each side of the string and another double DC fuse at the inverter side I'm hoping that in case of "mild lightning", I mean not direct lightning strike, fuses together with over voltage varistors would save my inverter. Each string gives 18Ap and fuses are 25A, so solar will never trigger them by itself. It's just my over engineering with a bit of hope in mind.
Air fryer and gingerbread house, seem like additional oddities to me 😊
I searched for a DC isolator switch when installing my first solar system
I could only find 160 volt DC switch
Knowing the danger of isolating DC I wired my solar in serie and parallel for a maksim of 126 volt
Since then the new inverters mppt range is 120 to 500 volt or higher
That present a problem
So the only way to isolate is to remove the load first
Switch everything off before isolating the pv supply
DC voltage and current flow cause a significant arc that is difficult to break and will burn the breakers
Any carbon caused by the arc in the breaker switch area will cause current flow and eventually a fire
45 Jr ago I observed in training the switch used to isolate 400 volt DC
The switch ( knife) had a separate blade parallel with the main blade that was attached to the main blade with a spring
When opening the main blade, the auxiliary blade remained connected and pulling out until the spring can cause the final current break at high speed
Faster than you can move the switch with your hand
That was used on 400 volt DC system's
Since then semiconductors scr igbt MOSFETs etc, made the need for isolating DC obsolete
Now we isolate on the ac system side
Solar pv isolating switch of the load current down to zero isolate.
My best bet would be some of THESE words: fungus, Joe, square, circle, gingerbread, Mail, air fryer.
Teacher A Trade, flame, Icon, cigar, few frights, Swiss Army knife, Boy Scouts, Ultra, kit for explosive areas, Grizzly Adams, and torque calibrated arm
Thank you :-)
My solar PV system was installed in 2015, and has DC & AC isolators. So far the only failure has been the AC isolator (a couple of years after installation).
Handy info. I would be interested to know how old the PV systems were that caught fire. My oldest system has been in for 13 years now and it's not caught fire yet. Maybe I should start checking the DC isolators with a thermal camera as a precaution?
Is the course available online
go for the full ZZ-Top!
The problem is people picking the wrong DC isolator and using them in the wrong configuration. Installers cutting costs by taking the link out and halving the current rating then putting two strings through the same DC isolator.
DC isolators are also excellent for any maintenance or repair works, what if you cannot depend on the built in DC isolator?
What if an MC4 has been damaged and you need to replace it?
Poor workmanship and purchasing inferior products is the problem here not DC isolators.
Livoltek battery in that solar training firms leaflet... cough reviewed that good system
My dc isolators are rated for 400V while it’s 360 volts so it’s should be fine, never had a single problem so far..
Instead of an isolator, could a switch to ground be as effective? ( Or between + and - of the solar leads) This way the contacts are not in use until that time of need. Could be installed as a single use emergency device to ensure solar voltage is zero.
Just how exactly can an dc isolator cause a fire.. If there is no power how does it set on fire...
But that recommendation clearly says: " . . . not intended for single residence dwellings . . . ". So HMO's and up?
no mention of why Isolators are bad? why?
There should be some regulations to minimize the fire risks: as few components between charge controller and solar panels as possible, minimize wiring between each component and all component rated with safety in mind (700V array => rated for 700V + 20% => 900V). Why you need to connect all solar panels in series? 30V per panel and 120V to 240V should be enough to build an array to get the cables down. Look what a cable isolation fault on a 700V system looks like and you never put the + and - cables in the same pipe.
I do not understand why UK electricians don’t explore micro inverters more. Easy to commission and much safer due to isolation and dealing with smaller DC voltage.
Would fuses have prevented the panel fires?
So what is the difference between the external isolator and the inverters built in isolator that makes the inverters built in isolator safer?
I’m gonna guess fungus and gingerbread as the two words you had to sneak in.
I guess you should’ve put all of your solar equipment on cement board, so that even if the switch burns up, it can’t catch anything on fire. Same with your batteries, inverters, solar charge controllers. Keep everything at least 20 feet from your house so that if it does catch on fire, it doesn’t burn your home down too. Stop putting solar panels on your roof. That should be common sense. Get some RF connected smoke detectors. Then buy some CO2 fire extinguishers to keep around.
I’m glad I don’t have solar and never will
yet, I had my bypassed and the electrician found the installers did a dodgy job as he worked on the bypass. I only have the isolators next to the inverter now, even though they did a dodgy job there too.
Solar panels are current sources and sholud be handled like those. Never open the circuits in current sources , they have to be short- circuit. solar inverters use this method to inactivate the solar power. input.
And you cannot protect current sources with fuses.
Cuurent sorces got a high internal resistace (Ri) , high open loop voltage so exact the other way round than voltage sources like the electical mains.
When install solar panels, never place connectors , taps or splittings underneath the roof /attic. Install wires in one piece from the panel to the inverter/charger. Use high cross sectional wire gauges, not because lower loss, but rather of the mechanical sturdiness. Install connection boxes in a fireproof environment e.g on a brick walls. Do not store flammable items in the vicinity of inverters and solar installations.
Battery banks shoud not be installs inside of homes / flats. The best is a separate shelter apart from the house.
If the Victron system had no DC isolator switch, why mention it here? Are there no example cases where the DC isolator switch actually caused the issue?
Australia has plenty
@@efixx Then use those as an example, or make the video title match what issues are actually shown.
Groovy, thanks.
This morning I tested a mc4 connector to see if it would burn result they support fire and do not self extinguish
There for a damage mc4 plug in /out under load is a fire 🔥 risk
Why should you ever need to disconnect under load ?
they no why but if there is no isolator it could happen many soler System are install by in experience technician high voltage dc is not the same as ac and many early System were in install by unqualified technicians
More important is mc4 burn
Air fryer and Gingerbread. Great listen.
That's three words, not two.
@@deang5622 actually it's 6 words if we are being pedantic. At least someone read my comment 😂
Perhaps, with all the news of house fires allegedly being caused by photo voltaic systems, the creators of a training program might think of a different name than "Green Spark"
Happy new year guys.
Sorry may be just I'm just a bit thick Please explain How does an isolator cause a fire
Will the party telling you not to install isolators assist you if you have to replace an inverter? Are they going to come out and safely isolated because there are not many ways you can do that?
Shame you don't explain why solar isolators are considered dangerous. Why is this?
Gingerbread & Campari..? Good content, thanks.
Well that's an interesting concept. We allow companies to manufacture isolators that arnt fit for purpose and fail dangerously, then change the rules so they sent required anymore 🤷🏻♂️. In industry we often have multiple isolation points on motor circuits nobody ever said "you are introducing more potential failure points" what a cop out. 44 years since I started, back then if your isolator was rated at 32a 500v, that was it's all day rating 24/7/365. Would have been good for twice that short term. At the same time we have idiots complaining they can't fit solar batteries in lofts anymore.
Question. i rent a unit with a garage down stairs with only light circuit. probably has no earth (at least not at switch when i checked ). I want a power point supply to mess with hobby electronics only in shed. Can i take power off the light or is there a chargeable device that i can plug into mains in the unit and carry it downstairs to shed as a temporary power supply ? Thats assuming there is no earth at the light fitting when i get around to checking it.
As an electrical engineer I would just like to ask all the Sparky's on this channel how much temperature they think a small arc welder with IGBT's (so D.C.) generates.
Then think of why they call it an arc welder😂
This is a serious allegation about Victron energy's MPPT. Do you have a source for that?
The clock is ticking, only it isn’t. 5:06
Tis the law where I am; plus there is new standards for PV isolators
Don't want a fire? ENPHASE.