inexpensive panels
Hi all, I know nothing about this firm--but the prices appear to be low: https://www.santansolar.com/?fbclid=IwAR17Xx_DhkB3h13BFmTjqejxTlf92ZO7UsVEAiNjNmcyNzrOkJx9XgYN26c
Forum Discussion
SJ-Chris wrote:
I was able to test each 250w panel. They were producing at 37V and 9.1amps. Seemed very healthy. I'm curious if anyone can comment on the likely output of these to the batteries from the MPPT controller after the controller converts it to be used on my 12v system... Is there a simple equation for this?
-Chris
Hi Chris,
I would definitely go with 500 watt systems.
I'll be interested in your real life results.
High end MPPT charge controllers "steal" about 5% of the output.
500 watts X .95 = 475 watts X 5 hours = 2375 watt-hours (in perfect solar conditions).
Batteries "steal" 10%. I.E. use 100 amp-hours and return 110 amp-hours.
2375 X .9 ~= 2137 watt-hours sent to the battery.
Depending on the type of battery (a single 100 amp-hour) acceptance rates are, at 85% state of charge 12.5 amps
12.5 x 12 volts = 150 watts for each 100 amp-hour battery.
In SiO2 that is doubled to about 300 watts.
In Li the battery management systems typically limit charging to 1C or about 1200 watts.
So the answer to your question really depends on the type and number of battery in use.
