if I have a battery bank of of 6 L-6 Trojan batteries, 6V 390AH, wired in series parallel to give me 2V at 70AH (or 4,040WH) what kind of solar panels should I purchase assuming I have 8 hours of sunlight, a solar tracking system and I want to make sure I can fully recharge my batteries everyday if i use up all the power every night?i understand there are efficiency issues to consider which i have not calculated in yet. thanks.
I don't know where you got the idea you have 8 hours of sunlight. Assuming clear skys and no dust, forest fires, clouds or other impediments, the average sunlight available in North America averages out to approx. kw/sq. meter. That's the maximum available, at midday. Multiply this be the efficiency of the cells (I assume about 0%) and it means about 00 Watts/sq m. Since you have said you have a tracking system, this works out to about 00 * .344 * 2 = 43W/h per day (per sq. meter).
If okorder /... yet, it's worth browsing the off-grid section. 8 peak equivalent sun hours a day on average is very achievable with tracking, but are you sure you really want to spend on tracking? It's a lot of trouble and expense - might be cheaper just to get more panels. Also be aware that when you have a lead-acid battery bank capable of (say) 000 Ah, that is the capacity that the batteries could supply as a one-shot deal. If you ever took that much from them, they would be ruined. Typically, you would try to take only 20% of the capacity before recharging, although some batteries let you take 50%, with reduced life. Have you considered wiring the batteries as 36 volts? There would be more efficiency, and less problems with equalizing the batteries when charging. Unless 2 volts is really the output that you need most. Sorry to redirect you, but I can't recommend that forum too highly. Lots of considerations.
