Potential system plan

[KShomestead]

New to solar but researched a lot the last few days. I think I have a basic set up. My goal is to have backup power for potential grid down scenarios. 800-1200 watts of panels. (Probably 6x 190w panels.) A 60amp charge controller or 2x 40amp? 12v 800ah lifepo4 battery bank (8x100ah batteries), more ah if budget allows. And a 3500w power inverter. The goal is to power the refrigerator and cb/ham radio for 3-4 days without sun, or with daily sun- also power a small air conditioner (860watt, 33amp start up, 7.6amp running) on hot days during daylight hours.

Any glaring flaws in my proposed plan?
Backup plan is to delete the AC and downsize to 400-600w solar, 300-400ah 12v system, 30a charge controller, and 2000w inverter, to run just the fridge and radio 3-4 days without good light.

Either way, I'd like to stick with 12v so if I lose a panel or more in a storm, or if a battery goes bad, I can just downsize the array and keep using it, or expand a bit later without needing pairs of things.

 

[MichaelK]

Biggest mistake here is sticking with 12V. I learned that mistake early on in my own solar journey, and now I try to dissuade anyone else from taking that route. Your reasoning is flawed here. I've never "lost a panel" in a storm, or had a battery go bad.

Everything will be cheaper at 24V. You'll use thinner copper wire. You can use a lower amperage controller. Only the extra cost of the batteries is factored in.

You can buy a REAL 4000W inverter at 24V. It will have safety certification. A 3500W inverter at 12V is a scam product that is NOT UL-listed!

I'm seeing high-voltage residential-sized panels in the 250-275W range selling now for 50$ in my area. Four of those wired 2S2P could feed an inexpensive 40A MPPT controller like a Tracer 4210AN for a total of 325$ for both the panels and the controller. 440$ for four 6V CostCo golf-cart batteries, and XXX for a good inverter. I'd look at Samlex's products for something that is economical but UL-listed.

 

[KShomestead]

I was just finding this from help on another group. I'm gonna delete this soon and rework my whole plan.

 

[David in nh]

I was just finding this from help on another group. I'm gonna delete this soon and rework my whole plan.

no need to delete , we always like seeing plans evolve .
many of us have some bad feeling about 12v , my breaking point was when i figured out how much the wire was going to cost to run 12v lights and some other stuff 60 feet away and i wanted to add more panels but the cost of wire is 4 times as much , the problem is 12v is not very scalable
but there is many people on here that run 12v very happily.

we just tell you what we think be it good bad or in my case just plan wrong

even the 12v naysayers were always very helpful here kind of a case of been there done that

good luck

 

[KShomestead]

I think I'll get the same batteries but wire them in series pairs, and parallel the pairs. And instead look for an all in one charger/inverter that will basically run the AC directly off the solar on the hot days I have good light. Currently looking for a good unit that can feed the small AC, then I'll figure out how many panels I need of what size to reliably feed the charger/inverter. I think the all in one route will simplify things for me as a newbie.

 

[David in nh]

here is the small 12v system i started with there been a few updates along the lines

my furnace back up

this is my oil furnace battery back up , plus one outlet , it is a aimes hard wired 12v 1200 watt inverter with built in transfer switch , a home built battery 200ah lifepo4 with a overkill bms , not having to add other meters to see what was going made install much cleaner , the blue...

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