Solar crunch time! Please review my plan.
I would like begin my first post with a big thank you to all who have shared their knowledge and experience on this forum. Without that, I probably wouldn't be entering the solar jungle! I hope yo...
Forum Discussion
Hi BFL13,
Mostly I agree.
A larger bank will not cause the user to use more amp-hours for say running the microwave per day. But running a microwave on a 200 amp-hour bank is going to consume more amp-hours. The choice then, is either a larger bank (not always possible), or more wattage per 100 amp-hours to try to mitigate the "too small" capacity. That is what I mean when I say discharging is not linear. It depends on the size of the load. In my case the load is 1561 watts and that shows up as about 170 amps. The 400 watt coffee maker draws only 54 amps.
I believe in setting the battery bank size based on an energy audit. There are some variables such as frequency of use. When I was using the RV 50 nights per year I could get by with a smaller solar "farm", and by having a medium large battery bank I could do a week long trip without shore power or any generator use (no air conditioning, but all cooking and water heating done electrically). The goal was to have the RV behave as if it were on shore power 100% of the time. During storage, the solar panels would return the bank to bursting full for the next trip. It is true that I did rely on the alternator to do a lot of the "heavy lifting".
Now that I full time, my energy needs are no longer entirely met by solar, and the distance I travel is actually smaller. I could use a thousand watts of panels.
From May 1, 2009 to Oct 1, 2013 I did 125 deep cycles. Since then I've done a further 300 cycles. My batteries are showing their age. Last fall, they would still draw 125 amps from the Magnum inverter charger. Now they do not get near that number. The posts are showing evidence of corrosion, and the solar never gets down to the 1 amp level, so it really is time to replace them.
Because of my need to recharge in extreme cold, I've decided that AGM is the only sensible alternative. I think I can fit in four L-16 Surrette 400 amp-hour six volt jars. Some careful measuring will have to be done.
Mostly I agree.
A larger bank will not cause the user to use more amp-hours for say running the microwave per day. But running a microwave on a 200 amp-hour bank is going to consume more amp-hours. The choice then, is either a larger bank (not always possible), or more wattage per 100 amp-hours to try to mitigate the "too small" capacity. That is what I mean when I say discharging is not linear. It depends on the size of the load. In my case the load is 1561 watts and that shows up as about 170 amps. The 400 watt coffee maker draws only 54 amps.
I believe in setting the battery bank size based on an energy audit. There are some variables such as frequency of use. When I was using the RV 50 nights per year I could get by with a smaller solar "farm", and by having a medium large battery bank I could do a week long trip without shore power or any generator use (no air conditioning, but all cooking and water heating done electrically). The goal was to have the RV behave as if it were on shore power 100% of the time. During storage, the solar panels would return the bank to bursting full for the next trip. It is true that I did rely on the alternator to do a lot of the "heavy lifting".
Now that I full time, my energy needs are no longer entirely met by solar, and the distance I travel is actually smaller. I could use a thousand watts of panels.
From May 1, 2009 to Oct 1, 2013 I did 125 deep cycles. Since then I've done a further 300 cycles. My batteries are showing their age. Last fall, they would still draw 125 amps from the Magnum inverter charger. Now they do not get near that number. The posts are showing evidence of corrosion, and the solar never gets down to the 1 amp level, so it really is time to replace them.
Because of my need to recharge in extreme cold, I've decided that AGM is the only sensible alternative. I think I can fit in four L-16 Surrette 400 amp-hour six volt jars. Some careful measuring will have to be done.
