Home Heating w/ direct PV DC Solar Panels! PART 3 engineering safety controls for DIY space heaters
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- čas přidán 11. 09. 2024
- 🟢 Solar DC PV2L Home Heating Playlist - • Solar PV Electric Heat... I have been heating my home for a while now using converted space heaters that run straight off of solar panels and DC. In this video I address some of the safety concerns in running my converted space heaters directly off of DC Solar Photovoltaic power. AC heaters are unsafe to run off of DC without proper considerations and modifications. I will explain some of the differences in AC and DC, and how this impacts design and engineering choices during the conversion process.
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My DIY heaters use LOW VOLTAGE DC in the ~30-50V range, not high voltage. Therefore electrocution hazards are greatly reduced. But even 48V will "zap" a person and so should be handled with care and respect.
Converting an AC space heater to DC operation in the 30-50Vdc region requires a certain level of care and understanding to avoid accidental fires during operation. AC heaters were never intended to handle DC inputs. The switches and devices inside can fail when switching Direct Current. This video is part 3 in a series which documents my conversion of AC heaters to low voltage DC, and addresses the need for a straightforward non-electronic solution to over temperature, tip over and power on/off controls.
In the past I have also used car/truck cab heaters and PTC (positive temperature coefficient) heating elements to heat my home directly off of solar panels. But I eventually standardized on converted AC space heaters, because they don't need a fan usually. I now have over 8 converted heaters of various types running successfully off my solar panel arrays.
This method of heating straight off solar panels has an efficiency all of its own: the ability to heat your home with just 2 small skinny wires. Although solar thermal produces more heat, it is also far more complex, and can't cool your home in the summer like solar panels can. Therefore I choose to use my excess solar panels for home heating without any hesitation. Why let underutilized solar panels get old in the sun, after the batteries are full they can heat your home too.
Other videos you may be interested in:
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DC Solar Circuit Breakers in 5 Minutes
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Simple PV Solar heating for beginners (Car/truck and PTC heaters)
• Simple PV Solar Heatin...
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16A 42V DC tilt switch (tip over switch) amzn.to/46idwFk
Langir standard DC Solar Photovoltaic circuit breakers amzn.to/45b91el
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Music credits: by TuneTank, Pixabay
Welcome to the Solar Power Edge Channel - I am doing research into Solar PV electric heating concepts including PV-To-Load (PV2L) solar electric space heaters. My channel has a collection of videos I recorded about my various projects. For example, heating a home or shop with solar power directly using simple and robust heater designs. PV-to-Load is one of the many technical terms used to describe the operation of an electrical appliance directly from Photovoltaic Solar Panel arrays. Examples include heating loads, cooling, irrigation and so forth.
For a few years now I have been using DC PV Solar powered heaters of various types (car or truck cab heaters, Positive Temperature Coefficient or PTC and Quartz Infrared) to successfully heat my home and shop. My favorite heaters are the AC space heaters I converted to low voltage DC operation: they work extremely well but require significant modification to use safely. No batteries, inverters or high voltages are used in my heaters.
This concept has its own efficiency and advantages versus solar-thermal, such as simplicity, low cost, flexibility for use outside the heating season and the ability to heat a space through a couple of thin wires.
I got a 100W 12V crystalline panel (Northern Tool $159+ ) and two, 10W 12V ice scrapers (Hamricks $10 each ) . In parallel, buried in the center of a 35 gallon galvanized trash can full of sand, up on a metal dolly. It gets SUPER hot - 700C thermal cutoff - in daylight and stays warm all night. Still outside, saving up for a deep cycle battery to stabilize the voltage.
Really neat!!
@SolarPowerEdge I am planning on doing this with resistive wire and sand. With resistive wire, do I need a DC switch to prevent damage to my solar panels/MC connectors to remove?
Thank you for all the great info and your DC power videos.
Addendum to my first comment. I wonder if a hot water heater, using two installed 48vdc heating elements and wired to residential solar panels, could be used? But this tank could be placed in a larger metal enclosure and submerged/surrounded by sand, thus serving two purposes: Heating water while simultaneously giving off valuable heat in your house. The elements would be thermostatically protected within the tank. And dc breakers to the panels also installed for protection.
Your channel is really forward thinking. My hat is off to you!
My thoughts regarding the heating set up in several of your videos is as you state built with Safety first. As an electrician and electronics enthusiast, i concur. With that in mind, it might be best to simply buy these cheap heaters for parts only. Then remove the tip over "disconnect" switches all together. By that i mean diy your own permanently installed heater created in a metal/insulated enclosure. The tip over factor will not be an issue.
Also you can build it with oversize wiring and other quality parts as needed
If you have metal working tools such as a press brake, a professional enclosure can be made. Even a smaller cheap press brake can be purchased at Harbor freight or online. I built mine using scrap metal and my wire feed welder. Anyways. Just my thoughts.
@mr.makeit4037 Thank you for the kind feedback :) good ideas all around... I have a 30" brake, just need a coil of sheet metal and some practice, plus about 7 of me to keep up with all these projects :)
Really want to get a welder.. someday!
I have a bypass on the 240v PV input to charge controller and it goes to 240v baseboard heater. Right now I have a breaker and DC contactor in the feed to heater. I hope in the future to use the Aux control from the solar controller to control the bypass the pv . I also have a direct DC water heater that I control using an IGBT module - details of that on my youtube channel. I will watch more of your videos later when I have time.
Sounds really cool :) hope to post more vids soon about PV heating. Thanks for watching! DD
Thanks for the video look at the little kitty acting like she is Vanna White LOI. What a beautiful animal. I think I can do this.
@aunttriciaattic Hehe! Thanks for the kind comment... the cat is a real character :D
Have oil filled electric heaters been tested. They are inherently safer. Two in parallel Would get you to 48v area. Just a thought as I love the oil filled as a superior engineered product.
I have 2, the large radiator type with wheels. But had some problems with their integrity and a bit worried oil is leaking out. Could just be these particular units though. I won't give up on them just yet.
Forget the tip over switch. I bolted mine down. Am I ready to go? How many 100w panels does it take to turn the heater on?
It depends on the wattage of the heater and impedance. The white heater shown (with 2 tubes) has custom wound elements and needs around 1kw of panels, 50v or so. Those small PTC heaters can run off of 3-4 100w panels in series or parallel. It's a matter of choice - more powerful heater, you need a lot more panels. Currently running 3-4 heaters if it's sunny, does help keep us warm. 12 panels for the house supplemental heat but of course I want to add more.
Here's the PTC heaters I was referring to: czcams.com/video/wK3_lRSntRc/video.html
Maybe a DC contactor like ones used in electric golf carts is the type of switch you need. Maybe not a cheap solution.
Good idea. If they can handle a 48v golf cart motor I am sure they can handle heaters or any DC load.
Did You consider using DC DC step down converter or mppt charge regulator with load output for stabilizing DC voltage? It would simplify heater math.
@LaSek-q6t Yes! It would work and it's a good idea. I think in terms of a grid-down environment. What if electronics are harder to get? In that case, a simple resistance load combined with a "diode string" is very cheap, robust and simple and will regulate the voltage. I will try to do some video about this topic (resistance/solid state hybrid heating element) as soon as possible. (Waiting for cold weather to do heating projects)
Here are examples of diode-based solid state heating elements that regulate to volts-max-power range automatically with no complicated electronics. Hope you find these topics interesting. -Dave
czcams.com/video/6D0aUmkUQSQ/video.html
czcams.com/video/42XIbHA9Dv0/video.html
czcams.com/video/CRhkZp6ECHk/video.html
Hey, just for general info. I have heard the MPPT controller gets more juice out of the panels, so do you know if it will help in your setups when you install MPPT in the circuit before the heater? I read that MPPT can't directly drive an inverter, but this might be different case on direct resistive loads that work on fluctuating current.
Hi, you are right about this. I have been looking for a programmable or MPPT DC-DC converter but they are hard to find. There are 2 schools of thought, mine is to keep it dirt cheap and simple with direct drive PV (but lose a few watts) the other is to use an MPPT circuit to manage the impedance difference between the panels and resistive load. And gain every last watt. If I ever find a good DC circuit that can do this, maybe I'll review it and post the results
12 volt continuous duty solenoid,or higher d c voltage relay like for golf carts
@Reset-hesitant I bought a couple of those DC contactors to test with, just got to work out a "simple" power supply
Could you please show us how you installed the tip over switches??
@rigmedic6941 Hello, this is a quick response (faster than making a video).
I could still make a video if this is not enough. Just let me know exactly what you want to see. Unfortunately I never had time to finish this video and show the installation, sorry about that.
Option 1)
What I recommend is make a platform or base inside the heater that is perfectly level. It must be level with the orientation of the heater as much as possible. Then use an L bracket or similar to fasten the switches, perfectly vertical with at least 2 bolts. Also, the 2 switches should be synchronized, they need to open at pretty much the same moment.
Option 2)
Attach a small electrical box to the outside of the heater, place the tip over switches inside that. Make sure all wiring is covered and securely crimped, nothing exposed. That option looks a bit strange but it's all about safety - not looks. Hope this helps! DD
I can get ahold of brushless cab heaters (commercial/military) 12v to 48v they can’t handle more than 20 amps
Yes I've been seeing those around. I have some of the 48v ones. But as of now I switched to converted space heaters because they're "quiet" usually no fan. So far so good
What about powering heating element in a hot water heater?
@laneburgess1643 Good idea! it works... here is an emergency hot water heater made with only a cat litter bucket czcams.com/video/0HDAOUQ7Uns/video.html
Had you considered a Mercury switch?
Yes sir, although I had no success buying them - apparently they were banned awhile back (due to mercury content)
One Mercury switch for both on/off and tilt switch,
@1brasov Hi, I planned to experiment with mercury switches, but strangely could not find any. It turns out they are pretty much banned due to the mercury content.
Mercury Switch for tilt protection?
@1brasov Since making this video I found a contactor that works pretty well, but it requires a power supply. Hopefully will be able to make a video about it once some issues are solved.
What about this . . . a slow-blow fuse in parallel with the tilt switch? Stops the arc (because there's still an electrical connection) and then blows 500ms or a second later. What say ye?
Hmm interesting. One of those fuses that resets perhaps? Problem is it might reset endlessly. I've been investigating a (relatively) simple circuit to use in addition to the switch to suppress arcs and allow higher voltage but maintain safety. Possibly in a future video, didn't have time to cover it here unfortunately.
@@solarpoweredge I was thinking of one that would just blow. Maybe mount it on the front so you can see if it's blown. I haven't really thought it out, either. Just throwin' it out there! I'm glad you're making these vids. I've often wondered why there's not more people doing direct PV to heaters, given how much the price of panels has fallen.
@@unionse7en It would certainly need to be properly sized. Large enough to create a temporary path for current to flow so the switch doesn't arc out, and small enough to make sure it blows within a second or so. Personally, I'd experiment. It may not even need to be a slow-blow fuse. A standard fuse, properly sized, could do the trick. I'd start around 1A and test from there. See how it goes. Or said experimentation could show it to be a bad idea. If either of you test this, please post your results as it may be a while before I'm in a position to test it myself. Peace.
I like the idea of bridging the switch. Will post an update if I am successful at testing such a circuit. My hope is that by spreading this idea, manufacturers will start making mass-produced DC-rated space heaters. It would be so cheap and easy for them, they already have the tooling and manufacturing lines in place. Then we can just safely plug in excess solar power - no hacking, inventing or converting heaters required.
just athought, murcury switches to open the circuit if the heater is knocked over? i dont have any experience with large DC load curcuits and these switches. so dont know if that would be a good idea or not.
What about a delay relaying?
I need to try it. There are a handful of semi-electronic means as well. If I can come up with anything useful, I will be sure to record it.
Do they make DC rated mercury switches that can handle the amperage? Arc welding wouldn't be and issue with one of those.
Yep it's a great idea. I have spent significant time looking for mercury switches. Apparently they are not allowed to be sold any more. I found an auction for a heavy mercury switch with high amps, it was attached to a replacement part for some kind of old machinery. Sadly it appears they are no longer possible to buy. Wish I had gotten some before that happened. If anyone knows where to buy mercury switches that can handle 20-25 amps - please let us know...
@@solarpoweredge You could also do things a little backwards and wire your tilt switch to short to ground when tipped over. The breaker can handle it but you're going to have to break the now welded closed tilt switch if you want to reuse it. Beats burning the house down though... I'm an electrician and when we need to interrupt high current we use special switches with these things called arc chutes built into them. Would be a bit over kill for what you're doing but its a pretty cool way to deal with arcing. There's also arc runners and magnetic blowouts to deal with arcing. But these are just some cool things to add to your electrical knowledge, maybe they'll come in handy one day.
Thanks for the info... those switches sound intersting. I am for anything that stops a heater from burning everything down. One of my designs uses 2 synchronized DC tilt switches in series. Might do a more specific video on that in the future if things go well
Strange, your last comment does not show up here - at all. So I am replying to an invisible comment for the time being... First thanks for the kind feedback and I'm always thrilled when I can get anyone to watch my videos after all that grueling hard work :) I hope renewable energy does become more effectively utilized and part of that is getting young folks on board with it. I'd like to teach classes to young and college folks about solar, maybe someday. Checked out your website... wishing you the best. Please stay tuned.... My hope is to document several more cool solar power projects on here as soon as possible. Had a lot of things slowing me down lately - but I believe they will move out of the way so I can get some more videos uploaded for you guys.
@@solarpoweredge CZcams sometimes messes comments up, I've noticed it a lot lately. Wish you the best of luck! If I can get elected I will certainly be the loudest sitting member in Congress pushing for meaningful progress on renewable and efficient energy. Especially with the kids! That's so important! Maybe you can help play a roll in that someday and or turn it into a career or something, I'm all about empowering regular people. It's just difficult to reach the masses with my message or else I think I cold get a lot more people onboard. If you're good with WordPress and want to help the cause I'm looking for someone to help me finish my website. I'm trying to learn it all on my own and its kinds kicking my butt. I'd hire someone to do it, if I hadn't already put a ton of my own money into this campaign.
Will this work with a wind turbine for the night time
Hello, yes it can work. This is basically like a dump load. Need to match the heater impedance to the turbine of course. If only I had a wind turbine, I would have already hooked a heater up!
@@solarpoweredge the power of a wind turbine can be volatile however it could help greatly with the heating crisis around the world if done correctly
Good thinking... Right on!
It's still not making any sense. A 1500w space heat barely heats one room, much less a house. A much better plan is to use solar to run an electric blanket and heat your body instead of the air
At the beginning of the series the channel host was clear that this was meant to be supplemental heating. That said, 1500W could certainly heat a standard sized bedroom on most New England winter days, though probably not the coldest of them. And 1500W, even 750W, could work wonders in an RV or a van, even in the winter. I know a woman in a 25' RV who heats with a 1500W heater through the winter in NH. She does need to light a few candles on those really cold ones, tho!
3 factors to consider: insulation (R value) in the construction, square footage and the climate (how cold it is). For my climate, R value and bedroom size, a 1500w space heater would be too hot most of the time. Only need 500w. When it's really cold, 1000-1500w running all day should be enough. In my living room, I run 2-3 solar powered space heaters for supplemental heat, depends on the sun. If it's not enough, I fire up the propane. Works so well. Already got them out for this season and wired up.
Right on and thanks for the comment! I only heat 1 20x20 bedroom, partial living room and 1 partial shop currently. fyi I have 14 solar panels (max) for heating. What could be done if I had more solar panels? Maybe someday :)
tilt switch, auto reset breaker and slow blow fuse or.... tilt switch, slow blow and manual reset breaker ?
Yes that could work, anything to disable the heater instantly. I may spend some more time looking for more breaker and fuse options that are suitable for this project