I set up a small array temporarily while we build our house. We’re in east TN and I used a solar calculator to figure a 29 degree tilt and south facing for my panels. For now we just have 22 100w panels so we are using a generator to charge if we run a portable AC. The most productivity I’ve had is 1050w and thats rare, I didn’t expect 2200w ever but it seems low. At the moment we couldn’t afford lithium so we went with group 29 deep cycle lead acid batteries. I’m guessing my math is off since I’m new at this. I’m running a 48v system with 12 total batteries so that should be 122 ah x 12v = 1464w x 12 = 17,568w capacity. I know I can only use 1/2 of that so lets say 8500w useable capacity. I can only run the house for about 1-2 hrs at 1200w to go from 52v to 46v and start the generator again even mid day with the PV. Where is my mistake?
100w Panel output and battery capacity issues
- Thread starter TimG303
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MurphyGuy
It just needs a bigger hammer
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22 of the 100 watt panels? What brand? Age? How are they wired?
What charge controller are you using and what are the settings on it? What inverter? How have you verified the battery voltage?
Have you checked to make sure the bats have water? Were these new batteries?
What charge controller are you using and what are the settings on it? What inverter? How have you verified the battery voltage?
Have you checked to make sure the bats have water? Were these new batteries?
sunshine_eggo
Happy Breffast!
2200W/48V = 45.8A - you need a MPPT with this much or more output current, and it must be properly configured to operate with the controller. Having a hard time picturing how you would wire 22 panels for a 48V system unless you have a very high Voc MPPT and have an 11S2P array.
12 12V @ 122Ah = is indeed 17.568kWh. 8500Wh usable.
48V * 3 * 122Ah = 17.568kWh
Assuming 4S3P battery bank.
Lead acid is rated for C20, so if you use more than 18.3A, you will not achieve rated capacity.
46V under load may be fine. If you remove the load, and the voltages bounce higher, that means you're at a higher state of charge than is indicated by 46V.
Critical that all 12V be at the same voltage when at peak system voltage. Should be charging to at least 57.6V for 2-4 hours unless your battery manufacturer states otherwise.
More info will yield better answers
12 12V @ 122Ah = is indeed 17.568kWh. 8500Wh usable.
48V * 3 * 122Ah = 17.568kWh
Assuming 4S3P battery bank.
Lead acid is rated for C20, so if you use more than 18.3A, you will not achieve rated capacity.
46V under load may be fine. If you remove the load, and the voltages bounce higher, that means you're at a higher state of charge than is indicated by 46V.
Critical that all 12V be at the same voltage when at peak system voltage. Should be charging to at least 57.6V for 2-4 hours unless your battery manufacturer states otherwise.
More info will yield better answers
Thanks for the info! I currently have it set to charge to 56v I will adjust.
The panel’s are wired in series
MurphyGuy
It just needs a bigger hammer
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I doubt 1.6 volts of difference (56 vs 57.6) is going to make a huge difference in this situation. Have you verified you don't have a bad battery cell in there?
You might need to test the individual batteries to see if one bad unit is dragging down the rest. A volt meter and hydrometer will be needed.
At this point, I think you're going to need to start checking each individual component to make sure its doing what its supposed to do, and my money is on a bad battery somewhere in that group.
You might also consider popping the caps to check for proper water levels. Low water will kill a battery in a big hurry.
Picture of your array would help.
You say the house load is 1200w. Exactly how did you determine this? Based on your numbers either your batteries are not delivering capacity or your loading is higher than you expect. You might need to charge each battery separately using a good equalizing charger. First check the liquid level and add distilled water if needed.
22 panels 24.5Voc in series is 539Voc. What is the rating for your EG4? If you are in excess you can damage things.
It has 4 separate charge controllers rated for 122-500 V each and can have up to 12 KW in panels hooked to it. I should have specified I have 18 on PV 1 and 4 on PV 2. Even if they were all hooked together they don’t actually output near 500v but I wanted to be safe.
1200 W is an over estimate but wanted to be on the safe side. I have a small portable AC running which cycles so it doesn’t actually draw the thousand watts about half the time it is only running the fan. I also have a refrigerator and some led lights. I verified draw with one of the plug-in load meters and off of the screen on the EG4
MurphyGuy
It just needs a bigger hammer
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Start checking those batteries.. You'll have to isolate them but I'm betting you have a bad cell.
Might want to use a hydrometer too..
If you are only running 4 in series on the second SCC than you may not be providing enough voltage to start it going. 4 X 24.5Voc is only 98Voc and likely only 84 volts.
Just checked the battery voltage. The 8 batteries in the back are 12.55v, the bank in front is a little weird. The battery on the left is 12.22, both middle ones are 12.98 and the right one is 12.39. Does that mean the outer ones are both bad and dragging the system down or could it just be that they are experiencing more load than the others? I did try to make sure all of the battery cables were the same length.
OK, it does show that it’s charging, but it’s definitely not producing the same rate per panel as the other array
I think I’m going to buy bigger panels once we get the house finished and stay away from the hundred watt panels
One other thing. It does not hurt to check if you unit is reading the incoming amps/watts correctly. My latest AIO is reading low compared to a reading from a DC clamp on and voltage measurement, W=VA.
I’m guessing there’s numbers mean the two outer batteries are draining and need to be replaced, but why would that make the voltage so much higher on the middle batteries?
sunshine_eggo
Happy Breffast!
Ah... Wally world bateries... Those are NOT 122Ah batteries. They're a BS C122 rating, i.e., 1A. They are closer to 90Ah.
You've gone about as low end as you can go. They are not true deep cycle batteries, and they're not going to last. The next penny you spend on the system needs to be on better batteries.
Charging to 14.4V vs. 14.0V per 12V is going to make a significant difference. Lower charge voltages mean MUCH longer absorption times at lower states of charge. It's likely that you're not getting these batteries anywhere near fully charged.
Dirty batteries behave poorly, and discourages proper maintenance. The tops of all the batteries need to be clean to prevent any conductivity between terminals AND ensure there is no debris to fall into the cells when you are regularly opening them up to check them and add distilled water.
22S... do you have ANY shading of any kind at any time of day?
How are the batteries' specific gravity readings? You have 72 cells to check, and they can only be checked meaningfully at full charge and using a correct technique. It's a drag.
You need to become an expert on FLA:
www.trojanbattery.com
You've gone about as low end as you can go. They are not true deep cycle batteries, and they're not going to last. The next penny you spend on the system needs to be on better batteries.
Charging to 14.4V vs. 14.0V per 12V is going to make a significant difference. Lower charge voltages mean MUCH longer absorption times at lower states of charge. It's likely that you're not getting these batteries anywhere near fully charged.
Dirty batteries behave poorly, and discourages proper maintenance. The tops of all the batteries need to be clean to prevent any conductivity between terminals AND ensure there is no debris to fall into the cells when you are regularly opening them up to check them and add distilled water.
22S... do you have ANY shading of any kind at any time of day?
How are the batteries' specific gravity readings? You have 72 cells to check, and they can only be checked meaningfully at full charge and using a correct technique. It's a drag.
You need to become an expert on FLA:
Trojan Battery | Battery Maintenance
The key to achieving optimum performance and long battery life is to follow a regular care and maintenance program. Read our tips for high performance battery maintenance.
www.trojanbattery.com
Unfortunately lithium is not in the budget at the moment. The only reason I bought those is because no one else even had that many matching batteries in stock. I don’t even have a hydrometer haha. I’m getting close to the point where everything is going to go in the garbage and I’ll hook up to the grid. 8k in garbage. Should have just paid the 1k to hook to the grid lolAh... Wally world bateries... Those are NOT 122Ah batteries. They're a BS C122 rating, i.e., 1A. They are closer to 90Ah.
You've gone about as low end as you can go. They are not true deep cycle batteries, and they're not going to last. The next penny you spend on the system needs to be on better batteries.
Charging to 14.4V vs. 14.0V per 12V is going to make a significant difference. Lower charge voltages mean MUCH longer absorption times at lower states of charge. It's likely that you're not getting these batteries anywhere near fully charged.
Dirty batteries behave poorly, and discourages proper maintenance. The tops of all the batteries need to be clean to prevent any conductivity between terminals AND ensure there is no debris to fall into the cells when you are regularly opening them up to check them and add distilled water.
22S... do you have ANY shading of any kind at any time of day?
How are the batteries' specific gravity readings? You have 72 cells to check, and they can only be checked meaningfully at full charge and using a correct technique. It's a drag.
You need to become an expert on FLA:
Trojan Battery | Battery Maintenance
The key to achieving optimum performance and long battery life is to follow a regular care and maintenance program. Read our tips for high performance battery maintenance.
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