Solar panel purpose on used motorhome

[SteveWoz]

I purchased a used motorhome last winter and besides the fun of taking trips it has also been enjoyable to learn about the various systems and make numerous (of course) minor repairs and improvements. One thing I haven't spent any time learning about is the solar panel that was installed by a previous owner that I found installed on top of one of the AC units. I presume that the purpose of this panel is to keep the batteries topped off while in storage. Does that seem likely to you experts or could there be some other use for this? I suppose I could and should trace the wiring to wherever it leads but I haven't gotten around to that yet. Thanks in advance.

[Lwiddis]

“If I remember right, the output is around 5 amps”

Five amps would be an 80 to 90 watt panel and far larger than an AC unit. Did you mean 5 watts?

[Acampingwewillg]

I had a very small solar panel and its only purpose was to keep the Solar Refrig Vent fan operational during daylight.

[SteveWoz]

Thank you, everyone. Your comments pretty much confirm my assumption but I think I'll try the voltage tests that a couple of you described. Happy camping, all!

[Chum_lee]

As others have stated, it most likely came that way from the factory as a trickle charge maintainer. (my '99 Class A has the same thing)
Normally the panel is about 12" square. When clean and new, a reasonable output expectation would be about 8 to 12 watts or at 12 volts nominal, less than one amp which is essentially, . . . . . useless for just about anything other than running a small transistor radio or charging your cell phone. Sorry but don't get your hopes up, you'll need a lot more panel area than that for any type of meaningful solar power generation.

Chum lee

[time2roll]

Yes that tiny panel will attempt to keep the house battery charged. If you plan to rely on it I recommend you monitor the battery voltage at least weekly to determine if the batteries are staying charged.

The 12 Volt Side of Life

[fyrflie]

I have the same size solar panel you are describing. Mine came from the factory with it.
It’s sole purpose is to keep the chassis battery topped off.

If I remember right, the output is around 5 amps. So not really enough to charge anything but enough to overcome parasitic loss while the RV sits.

[BFL13]

In sunlight, with engine off, shore power off (so no converter charging)put your voltmeter on the engine batt and the house batt. if one is 12.x and the other is 13.x, now you know.

If both are 13.x make sure your relay for engine to house batt is really open. If both are 12.X, the solar is doing nothing.

[Lwiddis]

A panel that small could, or could try, to keep either the house or chassis batteries charged. Identify what batteries the panel are hooked to, the panel’s max output and if it’s enough. You need a “plan” for whichever batteries are not hooked to this panel. My 30 watt panel is more than enough to keep the house batteries maintained during storage and while covered.

[rockylarson]

A solar panel small enough to fit on top of the A/C is probably a trickle charger for the engine (chassis) battery. Something that small may not have a controller and be directly attached to the battery. That is the first place to look.

[MDKMDK]

Solar panels produce electricity. Charging batteries is one use for it. Directly powering something during daylight hours might be another.

What kind of motorhome is it?
Year/make/model in your signature always helps others make better guesses.