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Old 04-05-14, 09:13 PM   #8
OffGridKindaGuy
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Default Battery Sizing

Quote:
Originally Posted by bte52 View Post
I thought that I would relate some of the specs of the solar panel (2 50W in series)

Related Power 100W
Vop = 17.9V
Working Current (lop) = 5.59A
Output Tolerance = +/-3%
Working Current (lop) = 5.59A Round that to 5 amps. (Nothing's perfect)

Design for the worst.. December. You will average ~2 hrs. of charge time. In great conditions, panels angled correctly, you'll collect ~10 aHr. max. at the battery..

This amount also dictates your usage. If you use more than you collect, you'll ruin the battery over time. This will vary with current weather conditions. The goal is to keep your usage at or less than you collect in a day..

During June, you should be able to collect at least 25 aHr. (5 hr. prime charge time) I'd say that's about the maximum to be expected with 100 watts of panel. That equals to 25% of the capacity of the battery that you now have, which limits your usage to 25 aHr. I'd say that's a good balance. You could go with more battery but remember, it will take more time to charge. If you discharge it more than you can collect, it could take days to bring it back to full without using the system for anything. It could become a vicious cycle..
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