diy solar

diy solar

Where do I begin?

Pgh-skip

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Jan 18, 2022
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I have an off-grid cabin that is unheated when I'm not there. It is located in western Pennsylvania and the winters can be cold. Is it possible to operate an off-grid solar system under these conditions? The only large inductive loads would be a 240volt well pump and a small refrigerator.
 
Start with a pencil and a sheet of paper. Make an itemized list of everything you want to power. Decide how many days without sun you can tolerate without starting a generator.

Your largest load is going to be your well-pump. That by far will require more power then anything else in your cabin.

For my cabin, which powers my 1hp well-pump, I have 4500W of panels powering a Schneider XW+6848 inverter. Eight Trojan L-16s were charged with a Midnight 200 charge controller. I recently upgraded the L-16s to 568Ah of Rolls batteries.
 
Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the Uber-Sun-Hours calculator site to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.
 
Sure with lead acid battery cold is no problem you just lose some capacity
as long as you leave your cabin with the battery’s full charged you are all good .
A big ac pump can be run with a generator and you can just fill a storage tank
and use a small ad or dc pump to pressurize the system.
I would use a inverter / charger so you can charge your batterys in the snow .
I’m in the Catskills in NY last year my panels where covered with snow for 10 weeks
I just run the Honda every morning and charge to full charge once a week or when I leave
I would use a 48v system With 8 6v golf cart battery’s a midnite or out back charge controller
with and 3000watts of solar
In the summer you will have way more power then you need .
In pa in the winter you can use as many solar panels as you can afford .
I have a 48v system with 16 6v gc battery’s and 4500watts of solar with a second 4500 watt solar bank
ready to go up.
Here’s the thing on a bad solar day in December I can get 250 and 400 watts for about 5 hours .
Things start getting better the 3rd week of January but you still have to deal with the snow .
 
Does anyone make a LiFePo4 battery that can be used in an unheated cabin in the Winter? I'm in western Pennsylvania, where we get winter nights in the single digits and lower. How about heated and insulated batteries?
 
Does anyone make a LiFePo4 battery that can be used in an unheated cabin in the Winter? I'm in western Pennsylvania, where we get winter nights in the single digits and lower. How about heated and insulated batteries?
Don't get fixated in Li. Lead-acid batteries would serve admirably, assuming you design properly and treat them right.
 
Does anyone make a LiFePo4 battery that can be used in an unheated cabin in the Winter? I'm in western Pennsylvania, where we get winter nights in the single digits and lower. How about heated and insulated batteries?

Don't get fixated in Li. Lead-acid batteries would serve admirably, assuming you design properly and treat them right.

^This

@Pgh-skip, consider that LFP gives the most benefit when cycled regularly. It's the $/cycle where they really shine. Given that it's clear your property is unoccupied for large stretches, you likely have a substantially reduced cycle count. This means that LFP's advantages diminish especially when you factor in the low temp challenges.

Consider that you won't get a lot of benefit for the premium attached to heated LFP other than bragging rights.
 
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