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Small Cabin Forum / Off-Grid Living / Electric Heaters and a bit of Solar
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paulz
Member
# Posted: 5 Oct 2020 11:10 - Edited by: paulz
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Finally got a cold morning around here. Cold for us anyhow, had to put long pants on and pee inside.

Want to augment the woodstove in our house bedroom this year with a space heater, electric being the simplest. And, afaik, most expensive to run. Reading about three types, radiant, ceramic and oil. Thinking radiant, why not? Some have fans I guess that blow the heat around.

On a side note, I will never use all 29 solar panels I have at the cabin, plus I have the grid tie inverters that came with, and my house in the 'burbs is basked in sunshine. Be nice to power some electric heat with them. But I don't want to get involved with grid tie, power company stuff. Would I need a typical off-grid, SCC and battery system to use them at my house?

Steve_S
Member
# Posted: 5 Oct 2020 12:13
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For ou to use te panels on your city housee without teh grid-tie nonsense, then yes, you would need an SCC, Inverter/Charger and all the related goodies that go with it.

You can elect to go with the simpler route of using AIO's (All-In-One" units which have the SCC, Inverter & Charger built-in. They are modular and repairable (well worn rabbit hole).

You may consider Growatt or MPP-Solar for such units, there are many out there, even by Q-Cell (yes the solar panel company makes all of this stuff too).

https://www.growatt-america.com/ * Better company, warranty and extras included + UL/ETL/CSA vertifications too.

https://www.mppsolar.com/v3/ Some UL/ETL/CSA has more "value" sub-lines.

BOTH Brands are Stackable, meaning you cvan link multiple AIOs together to increase capabilities.

These can seriously reduce BOS costs and many of the usual hassles of integrating eveything together. They also provide Common Under Interfaces to monitor, adjust & tweak everything going on.

Alternetaly a complete Victron Soltion might work out just as well but it would be more dear without a doubt. But you also know the quality behind it.

I can no longer recomend Midnite Solar as the company has more or less gone commatose since they started developing their own Inverters. Shame, was such a great company and totally dropped the ball, sadly.

Brettny
Member
# Posted: 6 Oct 2020 06:02
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Dont morning have little to no solar exposure?..the time you would want to use the heater.
Are you talking about directly linking pannels to a electric heater via a grid tie inverter?

paulz
Member
# Posted: 6 Oct 2020 07:43 - Edited by: paulz
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I was hoping you guys would do the thinking.
Still very much a solar rookie.

In it's simplest form, solar panels can power a dc heating element, as shown here:

https://www.youtube.com/watch?v=lQ68jPlnMxM&ab_channel=desertsun02

Yes, however, mostly at times when it's least needed. So, some sort of energy storage is required, battery and SCC being the norm. Perhaps some thermal storage, a water tank and radiator?

Would be fun to experiment but for me it will probably just be a room heater plugged into the grid power and pay the bill, at least this winter.

Appreciate the links on the All In Ones, Steve S. And the warning on Midnite. I keep reading and learning..

old243
Member
# Posted: 6 Oct 2020 09:39
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For single room heat, If you can install a wall mounted , baseboard heater , with a thermostat, either, wall mounted or on the heater. That would be best, they operate on 240 volts. Last indefinetly Keep your loads balanced. Shut off if you are not using it. We use an oil portable heater in our camper trailer. old243

paulz
Member
# Posted: 6 Oct 2020 11:43
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Thanks Old243. I have an old 110 baseboard heater, stand alone, but I was reading that they are not the most efficient. Radiant with a fan maybe. I have to go to Costco this morning, going to see what they have..

justins7
Member
# Posted: 6 Oct 2020 13:42
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I use electric space heaters a lot — too much — even though they are more expensive than other energy sources. I do have a woodstove, and also two Big Buddy propane heaters (which are great, but fumey). But nothing beats an electric heater's convenience (instant fuel delivery) and cleanliness.

I use an oil type electric heater for small spaces with a low-ceiling, since it is more of a slow, "rising" kind of heat (perfect for a bathroom). The others I use are oscillating types with fans in them, which I use for larger rooms.

I won't be happy when the electric bill comes, but right now I don't have any other options until I really start using the woodstove as it gets colder.

paulz
Member
# Posted: 6 Oct 2020 18:23 - Edited by: paulz
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I sold a motorcycle for 5k yesterday so I splurged on a $70 heater at Costco today. But I'll save the receipt..
20201006_111133_resi.jpg
20201006_111133_resi.jpg


scott100
Member
# Posted: 7 Oct 2020 23:09
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Do the math, but I think you'll find that electric space heating and a small solar system won't be a good match due to the power use of an electric heater.

Another idea you might look into would be to make a solar hot air space heater. Then you will only be using your battery power to power a small circulation fan, if you go with an active system. I made a solar air heater several years ago that was a very effective and efficient heater. Used it in combination with a wood stove in our previous house prior to the installation of a geothermal (ground source) heat pump.

scott100
Member
# Posted: 7 Oct 2020 23:39
Reply 


Concerning the math, let's say your space heater is 1000 watts, and it runs 15 min out of every hour in a typical winter day / night. If so, that's 6 hrs run time in a 24 hour day, or 6000 watt hours per day. At 12 v, that converts to 500 amp hours battery storage needed. Double that to 1000 amp hours as you don't want to use more than 50% of the battery storage available.

You could do this with 10 x 6v golf cart batteries. This also doesn't give you any extra for cloudy days. Last, you would have to figure how many panels to supply that power in the dead of winter without a whole lot of sun available.

So that's what I was getting at above. Electric space heating uses a whole lot of power. The solar air heater idea uses very little, but only works when the sun is out.

ArtifactJack
Member
# Posted: 11 Oct 2020 17:37
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Using electric for heating is very costly. It takes a lot of amps/watts to make heat on a solar system, and is not feasible off grid. I use a 20K BTU propane heater at my 14x20 cabin with a loft. I do run a small dehumidifier on a timer because of the moisture from the propane, off my solar system/electric. It cost me around 60 dollars a month in propane during cold weather. A typical small electric heater only puts out 5K BTU and cost about 70 dollars a month to operate on the grid. If your just trying to keep a bedroom cozy a small propane heater would be a cheap, and warmer option. Crack a window if you use one also. You could probably put one in for around a couple hundred bucks if you buy the tanks and regulator used. Check on FB market for used heaters also. I run my heater on low and keeps it toasty in this cool weather. Usually just warm it up in the morning and night, about six hours a day of run time in the fall. I don't use heat to sleep unless its freezing at night. Of course in the winter I have to run it on low all the time to keep warm. My GF heats her whole house with a natural gas one. They are 99% efficient. I use two 30 pound tanks and have them filled at TSC. Hope this helps you stay warm and safe.

paulz
Member
# Posted: 5 Nov 2020 10:18
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So about a week ago I plugged in the heater I bought at Costco (pictured above) in our bedroom, and have used it a half dozen times. It has a remote. I didn't build a fire last night knowing we were heading to the cabin this morning. Pretty nice turning it on this morning without getting out of bed. The heat is noticeable (not helpful) right away, and a half hour later felt warm enough to get up and move around, and fire up the wood stove.

It's a handy thing, glad I got it. I have only run it about an hour at a time.

gcrank1
Member
# Posted: 5 Nov 2020 14:25 - Edited by: gcrank1
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We have done much the same for years at home with some aux elec heaters, use em to kick the chill off quick and easy (and my wife likes to rearrange the furniture so easy to relocate too). We never really saw our overall monthly elec + lp (and now ng for a couple years) go up with use like this. And we turn the gas furnace down to 62f at night too.
At the cabin we use a non-vented lp wall heater the same way, kick the chill off when we get there and run it until the wood stove is up and running.
Imo, using aux heating intelligently works without breaking the bank, you just need to define your tipping points.
As to trying to run elec off solar the math says it would have to be a pretty big set up; ime it wont be worth the effort if you have grid to hook to. Just sell the solar stuff you dont use for a profit and figure the money you make will offset the grid-elec you use.

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