Quote:
Originally Posted by BillG
You lost me with the math. With using your recommended 25% of capacity of a 12V 30Ah battery, I get 90 Wh, only 12.8 hours for the 7 watt LED that he wants to use.
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(12*30)*0.25=90
"There is an average of 3470 hours of sunlight per year (of a possible 4383) with an average of 9:30 of sunlight per day."
http://www.sacramento.climatemps.com/sunlight.php
This is for Sacramento which is more northern, not southern Ca. which has more avg sunlight.
So let's say there is substantial sun 7 hours out of that 9:30.
60w (Module size) = 420 wH per day avg. More than enough.
"The longest day of the year is 14:41 long and the shortest day is 9:18 long."
source:ibid
Using the shortest day which is dark 14.82 hours at 7w that's 103.74 wH required.
The percentage of our battery used is:
103.74/(12*30) = 28.8%