Too much solar!

[OffgridMatty]

I have a very small system in upstate NY that currently consists of three 375W solar panels (have a fourth but don't really need it), two 24v EG4 Lifepower batteries in parallel and a Growatt 24v 3000w inverter all in one. My cabin is off grid and is used on weekends year-round and occasionally for a week at a time in the summer. Winter was a challenge at times due to the limited sun and the fact that the system was off while I was away and freezing temperatures and charging LiFepo4 batteries doesn't mix. I still never ran out of usable battery power as I don't have running water in the winter months. I am now in the spring and summer months and my batteries are almost always within 75% to 100% charged. I have no option to share access power to a grid so it just seems like a waste. I really want to know what best practice is for battery longevity. I have thought about turning the PV off and letting the batteries discharge more while I'm at the cabin. Should I be concerned about keeping the high SOC for most of the summer. I needed the two batteries mostly to handle to well pump and small refrigerator start up. I'd love thoughts about what if anything I should do differently. Thanks!

 

[AntronX]

Voltage level + temperature is what degrades all types of Li batteries. Don't have your LFP sit at >3.4V/cell all the time and at >25 deg. C. Run small air conditioner with excess solar to keep battery room cool when away. There is not much else to do with such small amount of excess solar, i would not bother.

 

[timselectric]

You don't want to store the batteries at a high SOC.
As long as you are cycling the batteries, there's no concern.

 

[chrisski]

Probably best to do nothing different than you do now.

If it’s practical when not needed for months, leave at a reduced state of charge, 50% versus floating at 100%.

If you don’t leave alone for months or it’s not practical, just do nothing different. IMO, constant air conditioning when away is not worth it.

 

[OffgridMatty]

Voltage level + temperature is what degrades all types of Li batteries. Don't have your LFP sit at >3.4V/cell all the time and at >25 deg. C. Run small air conditioner with excess solar to keep battery room cool when away. There is not much else to do with such small amount of excess solar, i would not bother.

The cabin actually stays pretty cool through the summer months without AC. I may just turn the PV off at times to let the batteries cycle down a bit while I'm there and fill up again in my absence.

 

[Q-Dog]

It sounds just about perfect. As long as the batteries are not sitting at high state of charge for days on end you are fine.

 

[740GLE]

Are you running a fridge? What about a water bubbler? Nice small loads will keep the batteries in usable state.


What are your SCC settings? Bulk for 27.6-28v?

 

[OffgridMatty]

Are you running a fridge? What about a water bubbler? Nice small loads will keep the batteries in usable state.


What are your SCC settings? Bulk for 27.6-28v?

Yes I have the fridge running as my only load when away. I'll check the SCC settings. I have never adjusted anything except the battery type.