SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
The best place to pray for a good crop is at the end of a hoe!
Moderator, Treatment Free Beekeepers group on Facebook.
https://www.facebook.com/groups/treatmentfreebeekeepers/
It is a privilege to live, work and play in the traditional territory of the Salish People.
Better wood heat! -- -- Check out the 2023 Permaculture Technology Jamboree event! All about Permies, including Tutorials ---
Check this out! Only available for 24 hours!
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
Mike Haasl wrote:Cool, so it is a "thing"!
Ok, I could put a panel (or 3?) about 30' from the water heater. Is that close enough?
Next question... What kind of panel should I be looking for?
I see DC water heater elements that are 12v, 24v and 48v. I'm assuming that would match the panel(s)? If the panels put our more wattage than the heaters can deliver, is that a problem? I'm assuming so...
I'm hoping that by having just one of the two heater elements on solar, and 40 gallons of water to store the heat, that I should be able to avoid explosions by monitoring it on sunny days to see how hot the tank gets. They do make thermostats that you can put in line but I'm not sure if they'd need the hole that the other element is installed in.
It is a privilege to live, work and play in the traditional territory of the Salish People.
Better wood heat! -- -- Check out the 2023 Permaculture Technology Jamboree event! All about Permies, including Tutorials ---
Check this out! Only available for 24 hours!
"The future is something which everyone reaches at the rate of sixty minutes an hour, whatever he does, whoever he is." C.S. Lewis
"When the whole world is running towards a cliff, he who is running in the opposite direction appears to have lost his mind." C.S. Lewis
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
Mike Haasl wrote:Had an idea. Is it possible to modify a standard 40-50 gallon electric water heater to also run on solar? Currently it has two heat elements. Can you disconnect one and leave the other one to be controlled by the water heater brain. Then replace the other one with a DC heat element (if there is such a thing???) that runs off a dedicated solar panel.
Then I could turn off the breaker for the water heater in sunny seasons. The sun would heat the tank up (I hope) and if company comes and we need more hot water, turn the breaker back on.
Has anyone done something like this? Do they make DC replacement heat elements? Can a water heater work with one element hooked up? Should the upper one be on solar? Would one "standard" panel do enough or would I need a bunch of them?
Thanks!
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
Country oriented nerd with primary interests in alternate energy in particular solar. Dabble in gardening, trees, cob, soil building and a host of others.
Mike Haasl wrote:Had an idea. Is it possible to modify a standard 40-50 gallon electric water heater to also run on solar? Currently it has two heat elements. Can you disconnect one and leave the other one to be controlled by the water heater brain. Then replace the other one with a DC heat element (if there is such a thing???) that runs off a dedicated solar panel.
Then I could turn off the breaker for the water heater in sunny seasons. The sun would heat the tank up (I hope) and if company comes and we need more hot water, turn the breaker back on.
Has anyone done something like this? Do they make DC replacement heat elements? Can a water heater work with one element hooked up? Should the upper one be on solar? Would one "standard" panel do enough or would I need a bunch of them?
Thanks!
a dual element hotwater tank will have an upper and a lower thermostat. Disconnect ac power to the lower thermostat and use it as your safety overheating protection. Always better to have a mechanical safety backing up human memory whenever possible.Mike Haasl wrote:Thanks David! I don't have solar currently so no batteries to worry about. I'm a little confused about the thermostat... I do want to keep one of the two AC heater elements and the thermostat it runs off of. Is there a way to use that same thermostat to control the DC for the solar? Or are you talking about a second thermostat?
To really simplify things, I'm fine with not having a thermostat and seeing how hot it gets on a full sun day. I'm assuming with one or two panels I won't get over 150F. If I'm off base with that and it would get hotter, then I'd be fine going with one panel. I'd rather underheat the water and use electricity to finish the job, than make the system too complex for my simple mechanical brain.
Use the existing thermostat on your water heater to control a relay like this one
https://www.amazon.com/SSR-100DD-Solid-State-Relay-Module/dp/B07PFDJQLV/ref=mp_s_a_1_9?crid=2JQJK71C3I6RM&keywords=dc+solid+state+relay&qid=1643493270&sprefix=dc+aolid+%2Caps%2C118&sr=8-9
Carl Nystrom wrote:
Use the existing thermostat on your water heater to control a relay like this one
https://www.amazon.com/SSR-100DD-Solid-State-Relay-Module/dp/B07PFDJQLV/ref=mp_s_a_1_9?crid=2JQJK71C3I6RM&keywords=dc+solid+state+relay&qid=1643493270&sprefix=dc+aolid+%2Caps%2C118&sr=8-9
Have you used any of those, David? I ordered several different SSRs on amazon a couple years back, and they were all junk. Either they would not activate, or they had failed open, I do not recall. I wondered why the were like 1/10th the cost of ordering one from Grainger. The ones I paid 100 bucks for have been running flawlessly for years. And dont forget to put them on a heatsink. I imagine a high amperage contactor from a starter motor or something would also work.
Argue for your limitations and they are yours forever.
Ahh, thanks, I didn't realize there were two thermostats on a water heater. Mind blown :)David Baillie wrote: a dual element hotwater tank will have an upper and a lower thermostat. Disconnect ac power to the lower thermostat and use it as your safety overheating protection. Always better to have a mechanical safety backing up human memory whenever possible.
Cheers, let me know if you go for it!
David
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
I see DC water heater elements that are 12v, 24v and 48v. I'm assuming that would match the panel(s)? If the panels put our more wattage than the heaters can deliver, is that a problem? I'm assuming so...
Argue for your limitations and they are yours forever.
cindyl541
I didn't even have to replace the controls on the water heater
Jerry usually you install a relay to switch on the heating element. Maybe not yet but your thermostat will get all Carboned up from the DC arcing.Jerry Wood wrote:I've got 1050 watts of solar going directly to a 120vac heat element at 128vdc..and it works good.. I didn't even have to replace the controls on the water heater.. So yes you can do that.. Just wire your panels for the same voltage as the element calls for and you have it whooped
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
Zeek McGalla wrote:I’m late to the party here… but I have about 300’ of 3/4” poly pipe just sitting on my black shingled roof. I have the water circulating when the sun is out with a pump in the basement by the hot water tank. It does enough to get the water to 125f. I would suggest not making electricity with the sun… just use the sun to heat water. There are many ways to make a solar hot water heater. Think about how hot a garden hose gets when it sits in the sun in the summer! I am installing a commercially made hot water solar panel that was made by a now defunct company in Texas. See image.
Garden Master Program video course and ebook guide
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
Mike Haasl wrote:Hello brain trust, I'm back!!! Ok, I got my hands on two used solar panels. From the label on the back it says:
Rated power Pmax 327 W
Voltage Vmp 54.7 V Current Imp 5.98 A
Voc 64.9 V Isc 6.46 A
Maximum series fuse 20 A
I think that means that if I put them in series they'd generate something under 109.4 volts and 5.98 amps and a total wattage of 654 W. That's if they were new and these ain't. Or in parallel they'd make 54.7 V and 11.98 amps. They have the normal looking solar connectors on them that I've seen in videos. They're a black cylinder. If there are multiple kinds, please let me know, otherwise I'm assuming they're mc4.
Mike Haasl wrote:
To run these in to my water heater I think I'll have a run of 54 feet (give or take). I'm sure 49.9' would be much cheaper than 50.1'...
How fat a wire do I need for this? Seems like ones on Amazon are all 10awg which seems pretty beefy. Could I use UF-B (underground gray romex) for the majority of the run or do I need to do a straight shot with the solar wire?
Mike Haasl wrote:
Do I need a fuse or circuit breaker in this solar circuit? If so, what and where?
Mike Haasl wrote:
The grid power goes into the top of the current water heater. I suspect each leg of the 220 feeds one of the elements. So I can just disconnect the lower one and put wire nuts on to disable it. Then I run my fancy solar wires down to that spot on the water heater and.....The current element says 240V and 4500W on it. I'm pretty sure it's only getting 120V since there's only a red and black wire hooked up to it. My suspicion is that I can use this element for my solar feed without any issue. Or is the element too big for this little bit of juice and I should replace it with a DC element?
An unanswered question is the thermostat. If I'm going to use it, I'd need to get a DC thermostat. The current AC one slides into a clip system on my Richmond (Menards) water heater. They seem to make 12, 24 and 48V thermostats. But even in parallel these panels can do 54.7 V. Is that a problem or is it one of those things where nominal and actual dimensions are different? The DC thermostats seem to need to be bolted on to the tank. I guess I'd have to fiddle around to make sure it can fit on my heater. I'm trying not to modify it in case this whole pipe dream is a failure.
Mike Haasl wrote:
Thinking out loud about the thermostat here:
If I skip the thermostat, I'd be putting about 600 W of power into a 40 gallon tank of water. These would be pointed south so I'm guessing they would be making peak power for 4 hours, decent power for 4 more and a trickle for 4 more. Let's say 600W x 4 hours = 2.4kwh. Double it to account for the rest of the day to make 4.8 kwh. That's 16,400 BTU. Divide by 40 gallons and 8 pounds per gallon gives 51 degrees of temperature rise.
We use very little hot water each day. Maybe 5-10 gallons. Worst case (explosion wise) we're on vacation and it's sunny every day. I'm not sure what the heat loss of that water heater tank is... Seems like if it was at 140 and I turned the power off, that it wouldn't drop below 90 in 24 hours. So 4.8 kwh of heat could, maybe, possibly get dangerously hot after a few days.
Did I do that math right? Am I greatly overestimating the max power I'll get from these panels?
Thanks for all the help with this!
It is a privilege to live, work and play in the traditional territory of the Salish People.
Better wood heat! -- -- Check out the 2023 Permaculture Technology Jamboree event! All about Permies, including Tutorials ---
Check this out! Only available for 24 hours!
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2023 SKIP event at Wheaton Labs
If you have a bad day in October, have a slice of banana cream pie. And this tiny ad:
Tiny House Magazine (Issue 121)
https://permies.com/wiki/208685/Tiny-House-Magazine
|