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diy solar

48v Parallel vs 12v Series+Parallel?

AKExcalibur

Remote Solar Irrigation & IoT
Joined
Feb 28, 2021
Messages
10
Location
Central Washington state
tl;dr: Any reason to favor/oppose two 48v batteries over 4 12v batteries?

Hi, I'm upgrading an off-grid family cabin which has a small (900w of 1990 panels!) 24v solar system with 100Ah of year old Lead Acid batteries. I'm planning to put in a new 48v system, mostly to save on wiring in a 250' run to a new 4kw array I'm planning. For now, I'm planning to have about 100Ah (4800w) of battery capacity, and will spring for LiFePo4. This place is in the North Cascades of WA, so winter temperatures require battery heating in an insulated box.

I'm heavily considering getting two Renogy Smart 48v 50Ah batteries, as they have internal heating, and they're priced OK with the referral code. Battleborn heated batteries are an appealing option, but expensive. I'm not yet ready to go with lesser-warrantied options, as I need reliable cameras and irrigation control 5 hours from home.

I'm wondering if there might be benefits to just going with a series of four 12v LiFePo4 batteries though, as they're super reusable elsewhere, especially if I do build a big DIY powerwall in the future when I have more hacking time. Given a good charge controller and commercial internal BMSes, is there any technical consideration to be aware of? [Edit: clarified that the 48v or 12v options in the new batteries are both LiFePo4]
 
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Two Renogy Smart 48V 50ah batteries will give you pretty much 5 kWh of usable battery.
4 100ah lead acid will give you about 2.4 kWh of usable battery.

Compare the same chemistry and then you get the same energy. Different chemistry and far different usable energy.
 
Two Renogy Smart 48V 50ah batteries will give you pretty much 5 kWh of usable battery.
4 100ah lead acid will give you about 2.4 kWh of usable battery.

Compare the same chemistry and then you get the same energy. Different chemistry and far different usable energy.
No lead acid in the new system, sorry to confuse the old vs. new. I may keep a separate legacy system to run the 24 volt well pump, but I don't need irrigation if it's not sunny, heh.
 
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