diy solar

diy solar

Best battery

todfun

New Member
Joined
Aug 25, 2021
Messages
4
Purchased 8 100 watt panels. The load im worried about is a dc fridge They say 1 amp running and a furnace at 6 amps. Doing calc a 100 ah should do but I like to over kill. Looking at sok battery. can get two 100ah batteries or one 200ah. getting two seems better in case one goes out.
Thoughts
 
Personally I would get the single 200 amp battery. The single battery will be more compact and easier to wire and fewer connections. Batteries should be very reliable if they are treated properly. Most battery failures are a result of user error, and user error would kill both batteries. But you are correct in that if you get two and one fails, you will still have power. This is a personal choice.
 
supply:
2x 100ah@12.8 volts nominal in parallel = 2560 watt hours

draw:
1 amps * 12.8 volts nominal = 12.8 watts (assuming 100% duty cycle which is beyond conservative)
6 amps * 12.8 volts nominal = 76.8 watts
total = 89.6 watts

runtime:
2560 watt hours / 89.6 watts = 28.571428571 hours run-time.
 
There are some mighty efficient fridges out there these days, but you should look for the "Total Watt Hr. Stable Running" value if available.

I was considering this fridge/freezer combo that states a 584 Wh/24 hrs (set to -14°C in the freezer/+4 °C fridge performance in a +25°C ambient). Mind you that's at 24 volts but I wouldn't imagine the 12 volt value being much different, and if a freezer is not needed I could see the Wh/24 being much less:

 
Last edited:
We have a unique LP Fridge, the upfront cost of LP was way worth it. Two 100lb tanks gets us by for over a years worth of use, May thru October.

If I had to do it again with a standalone PV system, I’d still do an LP fridge.
 
We have a unique LP Fridge, the upfront cost of LP was way worth it. Two 100lb tanks gets us by for over a years worth of use, May thru October.

If I had to do it again with a standalone PV system, I’d still do an LP fridge.

I'm surprised you need two; we also have a unique LP fridge in addition to a propane oven/stove as well as hot water heater. May thru Oct use for us is still only two 100lb tanks!
 
Redundancy, we can drag one tank for filling while the fridge is still running, no need to relight the pilot.

We set up our system with two full tanks last August, ran the fridge until late October, fired it back up end of May, we kicked our first tank in early July.

We have an auto throwover regulator that switches tanks when a tank kicks. We also have some propane lights we use in the shoulder season (great heat source), plus a range for coffee and indoor cooking needs. So those two tanks run more than just the fridge but that’s majority of the load on them.
 
Last edited:
Purchased 8 100 watt panels. The load im worried about is a dc fridge They say 1 amp running and a furnace at 6 amps. Doing calc a 100 ah should do but I like to over kill. Looking at sok battery. can get two 100ah batteries or one 200ah. getting two seems better in case one goes out.
Thoughts
For me, 2 100ah/12v run in series then parallel with 2 others. That gives u a 24v battery bank.

Plenty for ur frig and furnace. Im totally with u on liking to overshoot. Thats y caught my eye ur using 100w panels.

Thats a tough recharge. Like dedicating 2 per battery is wayyy cutting it close. I overshoot and do 2 200w panels per 100ah battery.

Which leads to a big question: r u relying on battery recharge solely using solar?

Im a complete off-grid so do BUT most folks use some form of grid-tie... even if its a gas generator backup.
 
this is the link for the refrigerator conversion. https://jc-refrigeration.com/products/
I through a amp meter on it and came up with just over two amps. Them saying 1 amp is probably 24 volt as you can order either 24 or 12. I think im going with two 100ah batteries and two in case one goes bad hopefully will have second.
 
this is the link for the refrigerator conversion. https://jc-refrigeration.com/products/
I through a amp meter on it and came up with just over two amps. Them saying 1 amp is probably 24 volt as you can order either 24 or 12. I think im going with two 100ah batteries and two in case one goes bad hopefully will have second.
I looked over all their units, and most were 7.5A. Unless you have a propane unit, with a simple 12V fan electric load…
 
On this, while its preference, I agree and think u will be pleased in the end.

Like u said: anything goes wrong, the entire system doesnt collapse.

Probably the main reason, u c like 48v battery banks made from 4 12v 100ah is theres a lot more things u can do with 1 of them.

Like (Ive done this) say yr boat or motorhome wont crank. Yank 1 of ur batteries out and use it.
 
You should not use Lifpo batteries to start an engine, waaay too much current, you’ll fry the BMS/or at least test it’s over current.
 
Back
Top