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frankpaige
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# Posted: 10 Mar 2025 09:37pm
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What would be the results adding a chest freezer to this system?
2-100amp, Walmart Deep Cycle Marine Batteries
2-220 watt solar panels.
The freezer is 3.5 cu ft. Says it uses 193 KW a year.
Southern exposure is really great.
Would this be doable? Or do I? Need to add any panels? Add any batteries?
What am I missing.
Thanks
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Nobadays
Member
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# Posted: 10 Mar 2025 11:31pm
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What else are you running with this system?
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frankpaige
Member
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# Posted: 11 Mar 2025 08:50am
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Pretty much nothing.
I recharge the IPad, hearing aids at night.There is a rechargeable toothbrush every 5-6 days. There are a total of 3LED lights. Usually there is only one that is used. The rest. Microwave and coffee pot are handled with the Generator.
My hope is to turn the freezer down to what a refrigerator temps would be.
IDK
Just kicking thoughts around.
Thanks
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MtnDon
Member
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# Posted: 11 Mar 2025 08:54am
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Does that freezer run on DV or AC?
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frankpaige
Member
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# Posted: 11 Mar 2025 08:55am
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My plan is AC.
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paulz
Member
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# Posted: 11 Mar 2025 09:02am
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Can’t quote numbers but my little 1.5 cubic foot fridge has surprised me by freezing foods this winter. Temp difference between outside air and temp setting makes quite a difference. Mine is outside so frequently in the 50s in afternoon, down to high 30s overnight. So it doesn’t have to run that often and use much juice. That will change this summer, luckily the solar goes up then. Anyway the cooler you can make its location the better, I know you’re up in the mountains.
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Nobadays
Member
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# Posted: 11 Mar 2025 10:15am
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I'm assuming a 12v system...
193kwh/year = ~530wh/day
200ah @ 12v - 50% usable = ~1,200wh/day
2 x 220w panels - 440 x 5hr = 2,200wh/day but... I would not count on more than 80% so realistically - ~1,760wh
Theoretically yes, but with maybe two days without sun to dead batteries with your combined loads. This is maybe too tight if you plan to leave food in it when gone. I'd consider switching to 2 x lifepo4 100ah and maybe add a panel or two paired with a good MPPT SCC for better charging on mediocre sun days.
LiTime has 100ah lifepo4 with low temp protection and Bluetooth connectivity for ~$200 ea. The low temp protection works by not allowing charging below 32*F but does allow discharging down to -4*F.
If you do decide to move ahead, the best way to control a freezer (that I know of) is to use an Inkbird temp controller. Plug the Inkbird in the wall, the freezer into the Inkbird and the Inkbird temp probe in the freezer. This allows the controller to turn the freezer on and off as needed to hold the temperature you want. You can set a delay to protect the compressor and on/off temperature range. Best part is they are only about $35.
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gcrank1
Member
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# Posted: 11 Mar 2025 10:16am
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Thoughts:
The chest freezer will hold the cold better than an upright fridge
Putting prev cold stuff in it (at least the inside temp) wont make it run harder to cool down something warm
Once it hits saturation cold inside it wont cycle much
Panels are cheap if you buy used, get matching panels and get min of 3, run MPPT solar control, you wont regret being a bit over paneled for todays use, and use always rises.
Lead acid batteries will last best if only the top 25-30% of amps are taken, if you go 50% or deeper it dramatically shortens the time. The bat-bank is what will carry you overnight AND through a period of poor overcast recharge. So 200ah of bats really only has 50 to 60ah usable on a regular basis or you murder the bats. You can wire multiples of 12v bats in parallel but dont go more than 3; that would be 75-100ah.
You might want to consider 24v, wish I had. You can use smaller gauge wires on 24v and/or go longer distances for the gauge than at 12v. Def do this from panels to charge control (must have a 24v compatible, common now). It can intake 24v and put out 12 or 24v. If you use those same bats wired in series each pair make 24v and you can use up to 3 banks of 2 wired series/parallel, thus start with 2 and be expandable.
The inverter must then be 24v and output 120vac. The bigger the inverter the more it sucks amps just running itself. I suggest an inverter that has about 25% more capacity than your start-up load from the freezer.
In a typical 'days use' I liked my system to be able to recover the bat-bank fully by noon from the bat drawdown of the prev late afternoon and overnight (when there was use but no charging).
Fwiw, ours was 600w array, 24v to acc, 12v to bat-bank orig 400+ah to 12v to 120vac 1000w inverter and a 60' run from 'bat-shack' to cabin. I consider this a min size unless all you want is very basic; ie, no fridge, electricity. Some others may disagree.
Note that right now LFP batteries are the cheapest they have ever been but that may quickly change with the China tariffs where all the bat cells come from. LFP was a game changer for us as each 100ah LFP has easily 2x the available power as a lead acid bat; so half the batteries to deal with and FAR longer lifespan.
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Nobadays
Member
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# Posted: 11 Mar 2025 10:37am
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Another thought... I was using a Giandel (cheap'ish Chinese) inverter in my shop for a couple of years and this lead to very shortened life of some batteries.
This inverter is considered one of the "better" cheap inverters but it leaves a lot to be desired.
First is Idle power consumption which is many times higher than a comparable Victron inverter.
Secondly, and more importantly, there is no way to adjust the low battery cut-off point, it is preset. For a 12v inverter this is set at 9.5v!! This means the first time you hit a week of rain/snow your batteries will be drained to less than just dead!
These two issues are why we switched to Victron. Yes they are roughly twice the cost but not if you consider the cost of replacing the batteries ruined by the cheap inverter.
The Victron SCC is just heads above most other MPPT Controllers especially on marginal sun days.
My two cents! Hope it helps!
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