Thor Forums

[Wiley1]

Originally Posted by t1bone

Will my 100 watt solar panel keep my house battery charged at night? I shouldn't be using that much power during the day, so I wonder if it stores power for use at night?

I'll take a crack at the original OP question.
(Not trying to be funny, but I can't help myself)

No 100W solar panel will keep anything charged at night because the moon isn't bright enough. You will need your batteries for that.

Think of your battery bank as a bathtub full of electrons. At full charge, the bathtub is full. As you use power, the level goes down.
What you're really asking is: "After partially discharging my batteries overnight, will I be able to recharge them before the sun goes down, using only a single 100-watt solar panel".

The answer to that question depends on "How much power did I use?" and "How fast can I replace it?"

Battery capacity and "state-of-charge" are actually measured in Amp-hours.
If you pull 20 amps from the tub for 5 hours, you will want to put those Ah's back into the tub as soon as possible because batteries are happiest when they are full. An RV might have any of 4 charging methods available and you can use combine them: shore power, generator, vehicle alternator, and solar.

If you can supply 20A of charging current to your batteries, it will take something more that 5 hours to replenish them. If you only have 5A of charging current, it will take more than 20 hours.

Let's say you ran your fridge on propane the night before, so the only thing drawing power was that 32" TV and your CO/gas detector. You wake up before the sun and find that your batteries are down 32 Ah. Without an SoC analyzer, you would just have to guess at this.

Using the estimate provided by another member in this thread, let's say that your solar panel is able to produce only 50 watts at 12 volts, which is a little more than 4 amps. It will take you over 8 hours to recharge those batteries. On a cloudy day, it would take much longer. If you get a second 100W solar panel, you would cut that time in half.

Did I answer your question?