Sizing a battery bank. Ah VS wh?
Hi again! So, I'm trying to size out the battery bank I will need for my husband and I to live off grid in a camper. We don't have tons of time or money, so that's a bit of a factor. We plan on usi...
Forum Discussion
Lwiddis wrote:
“That seems like such a little amount. I thought it would be more about the solar's charging rates. Like "25amps per hour" or 25ah x 4.5hrs of sunlight = 100 amps charged in 'one day.' I havnt quite gotten to that research yet...”
Rarely do 300 watt solar panels produce 300 watts. The sun must be directly overhead, the temperature must be moderate and very importantly the batteries must be willing to accept 300 watts. During bulk charging they may but during absorption they won’t. The majority of the time recharging wet batteries are in the absorption phase. Lithium is different.
True they don't put out an instantaneous output of 300w often.
But I believe the point was if you take the nominal rating...it will generate total watt-hr per day of about 4 to 5 times the rating (ie: 300w of panels generate 1200-1500w-hr per day). They will actually output for far longer but at lower wattage for much of the day.
Solar also largely solves the issue of acceptance by default. Sometime after 2pm, as the angle of the sun gradually drops, so does the panel output as it gradually tails off for the next 3-4hrs (depends a bit on latitude, time of year and shading). Come 4-5pm, those 300w panels may only be throwing off 20-50w, so battery acceptance is less of an issue.
