My Solar Journey

denmendez65 said:
Yep thats the plan. In 5 years when I expect them to start packing up I will replace the entire bank with lithium. I will save some 2k a month for the solar expansion I will do going forward. The 24V inverter will run from a 10kwh bank probably and Ill add a 48V one to run any high power items I may need. Probably a 15kwh bank.
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Start looking at 1 to 2 years, gel batteries are not designed for this application really.
 
Lupus said:
Can't do that, he would need to gradually watch the capacity diminish and than replace the whole array.
Or just replace it as soon as possible with lfp, I've had gel it's possibly the worst battery for this scenario. Doesn't handle high draw very well, one or two dips below 24v and the batteries will be kaputski.
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Nah, if second LA battery in string still has capacity then life carries on with hybrid mix of LFP and LA.
 
wingnut771 said:
You forgetting peukert effect. LA has to discharge at C10 (10 hours) or C20 (20 hours) to get its rated capacity. LFP doesn't have this issue. Try discharge a LA battery in 1 hour and you probably only get maybe 60%.
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That doesnt apply to my system. The 20hr rate (100ah) for the GEL batteries I have is 5A. I have 5 parallel connections. Thats 25A to meet the 100ah rate. That means I can discharge 600W from them comfortably without hitting the Peurkert effect. More than enough for my 350 to 400W load at night.
 
Lupus said:
Start looking at 1 to 2 years, gel batteries are not designed for this application really.
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I would believe it if I didnt see all the cabin living guys in the US getting 8 to 10 years out of their systems. As mentioned, keep your DOD low and youll be fine. My GEL batteries are fully charged by 10:30 and float for 4 to 6 hours therafter. The system is designed to meet the charging requirements for GEL. Hence the 3.9kwp panels I have. In Summer this will be even better with the longer days.
 
denmendez65 said:
I would believe it if I didnt see all the cabin living guys in the US getting 8 to 10 years out of their systems. As mentioned, keep your DOD low and youll be fine. My GEL batteries are fully charged by 10:30 and float for 4 to 6 hours therafter. The system is designed to meet the charging requirements for GEL. Hence the 3.9kwp panels I have. In Summer this will be even better with the longer days.
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What temps do they experience?
 
wingnut771 said:
What temps do they experience?
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They never get hot if I'm being honest. They stay in a ventilated room with lots of cooling. I added a thermostat driven fan to keep them cool also. GEL batteries like to be between 15 and 30 so the fan turns on when the temp is over 30 which so far hasnt happened but I suspect it will come October this year.
 
denmendez65 said:
I would believe it if I didnt see all the cabin living guys in the US getting 8 to 10 years out of their systems. As mentioned, keep your DOD low and youll be fine. My GEL batteries are fully charged by 10:30 and float for 4 to 6 hours therafter. The system is designed to meet the charging requirements for GEL. Hence the 3.9kwp panels I have. In Summer this will be even better with the longer days.
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I've used gel and kept the DOD low, didn't really matter. If there is any high draw even for a few minutes, those batteries do not last. You'd have had more luck with normal LA batteries and saved even more money.
 
Lupus said:
I've used gel and kept the DOD low, didn't really matter. If there is any high draw even for a few minutes, those batteries do not last. You'd have had more luck with normal LA batteries and saved even more money.
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I added protection against that. The highest load I experience is during the day and the most I've see my inverter peak to was 3kw but battery draw has never passed 60A (The rest comes from solar directly). For GEL you don't want to discharge more than 30A continously or you damage the batteries. I have a 125A DC breaker to trip if the inverter tries to pull more than 125A from the bank. Thats a max of 25A per battery string. Well within the limits of each battery. I did lots of research on this lol.

I have also since reconfigured things to stop any battery usage during the day to let them float charge properly.
 
Lupus said:
I've used gel and kept the DOD low, didn't really matter. If there is any high draw even for a few minutes, those batteries do not last. You'd have had more luck with normal LA batteries and saved even more money.
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He's got 5 batteries in parallel.
 
Lupus said:
Sure I only went to 2 :) but the gel did die a lot quicker than the LA with the same usage.
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Time will tell if my experiment will work. I just need 3 years to payback the entire system. 1 year to payback the batteries alone. So even if I reduce the expected lifespan for the batteries from 5 years to 3, its still a big win. I am basing the payback on the fact that I save about 1k a month in electricity now compared to when I didn't have solar. They allowed me to get into it which the upfront cost for lithium didn't allow me to. I am close to halfway there to paying back the batteries alone since I went "off grid" at the moment and they are going strong with no issues or loss in capacity 6 months in.
 
denmendez65 said:
Time will tell if my experiment will work. I just need 3 years to payback the entire system. 1 year to payback the batteries alone. So even if I reduce the expected lifespan for the batteries from 5 years to 3, its still a big win. I am basing the payback on the fact that I save about 1k a month in electricity now compared to when I didn't have solar. They allowed me to get into it which the upfront cost for lithium didn't allow me to. I am close to halfway there to paying back the batteries alone since I went "off grid" at the moment and they are going strong with no issues or loss in capacity 6 months in.
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Plus a good learning experience and learning is always valuable
 
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rh1 said:
My previous job, my colleague went with lead acids as it was cheaper and I went lithium thanks to the advice on these forums. My colleague only looked at the initial savings. Just after year later after the multiple load shedding slots per day. Her batteries were dead.
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Yup that happens when somebody sees the same capacity as much more expensive options but don't realise you can never discharge lead acid batteries that low without damaging them. OP has definitely done the right thing here, not to say I would ever want to faff with all that effort of babying lead acids ever again.
 
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