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I am looking for an enclosed trailer to convert into a camper of sorts. My plan is to add a deep cycle battery for lights, radio, and other accessories. How much solar power would be required to adequately charge a 12 volt deep cycle(marine) battery during the daylight hours? I know it would depend on how much the battery is drained each day, so say I used 50% of the battery charge each day.

There are other variables involved such as how much power you want to use each day. Use that as your calculation and build your system based on those numbers.

For example, say you want to use about 1000 watts per day total. Lets say 100 watts for 10 hours. Then depending on where you live, consider there is about 5 peak sunlight hours per day.

You need about 200 watts of solar panels to give you 1000 watts in 5 hours. Add more for safety and to cover cloudy days.

The batteries for such a system would be about 83 amp hours, but a battery bank is considered drained at 50% so you need about 160 amp hours of batteries.

Hope this helps some

even more battery standby power would be better, the bigger the bank, the lesser the strain you put on it, the longer they live, and the lesser yoy load them the better it is for a lead acid battery, i always say , you cant have a to big battery bank.

and also inportant is that the bigger the instalation connected to it , the more advisable it is tu use bigger battery bank voltages .

not only smaller wires , but also mutch less strain on the bank.

the instalation i use on my offgrid tugboat here in the netherlands is 24 volts at 460 amps,
only have a smal solar system on the roof off the wheelhouse with two panels of 140 wats in series, delivering 45 volts at 8 amps to my mppt controller , max charge amps y have seen is around 15 amps at 24 volts.(my controller is max 15 amps, i'm experementing with differend makes and types of chargers)
i power a compressor fridge via a inverter at 230 volts ac , a tv, gsm charger and other misilainius (i can also use a washing machine on it, but when y use that i will mostly start my 7kva 230v diesel generator, letting it charge my battery bank the same time via the inverter /charger (50 amps), to top up the battery bank.
also when y use bigger loads i often start that generator, not to stress my bank to mutch, used yhis system for over 18 years, average battery bank life is 10 to 12 years, using quality semy traction batterys, connected serie/parralel.

works fine for me!

Mr bugsier, your system sounds pretty good. The mppt controller makes a huge difference. One day I would love to make it out there and see your boat. Its a dream I always had to live on a boat.

Hello all. This is HBW from Youtube. This is really all mathematical. Let me insert the equations below:

Angle of the panels:
Angle = latitude*0.76+3.1

Array sizing:

Use http://www.sunrisesunset.com" onclick="window.open(this.href);return false; to determine the worse of the worse.
Worse day in Jan/Feb and compute total hours of sun / 2 = Worse case sun hours
Worse case sun hours 4.875

(Total Power Requirements in kW * 1000 / Worse case sun hours) * 2 = Array size

(4kwh * 1000 / 4.875) * 2 = 1641w

Reserve Power Battery Calculation:

((Total Power Requirements * 1000 x reserve days) / battery voltage) * 2 (because we never want to go lower than 50% discharge)

((4kwh * 1000 * 5) / 24V) * 2 = 1666.7
((4kwh * 1000 * 5) / 48V) * 2 = 833.3

To compute the number of batteries:

(Reserve Power Battery / Battery reserve cap) * the number of batteries to make the voltage

(1666.7 / 210rc) * 2 (24v using 2 12v) = 16
(833.3 / 210rc) * 4 (48v using 4 12v) = 16

It's going to be 16 either way and heavier copper cable is expensive and the component cost is the same; so 48v configuration.

If there is any questions I'll be around.