Solar Battery Tender

A disconnect switch on each bank will allow for extended storage. Even if you use say a 100W panel on the house battery consider a disconnect switch (solar bypasses the switch).

I don't know exactly what you are willing to settle for or what you want to pay, but, I have a Deltran Solar Battery Tender. It is not a charger in the sense every one here seems to be talking about, it is a tender that will maintain either my chassis or my house batteries IF they are fully charged to start with. I know and I acknowledge that it has little or no chance of charging a low battery.

At one time, folks that remove their batteries during the winter and keep them in a garage or shop were praising the Deltran Battery Minder(120vac) for keeping their batteries topped off.

I will admit that the Battery Minder will run 24 hours a day and may do a better job than the Solar Battery Tender but I have found it satisfactory between trips.

My opinion only, many have and will disagree.

For the effort I would get 100 watts minimum.

I did install a battery disconnect. While I don't want to pay for 300w of solar I do want to keep the batteries charged during storage and maybe even run my generator less on the few boondock trips we take. I am now thinking that 100w will keep the battery charged but am still wondering if that might be enough to also recharge during the day while on trips. I have no inverter and no plans for one. I have also changed all interior lights to LED. Thanks for the great advice so far.
RichH

Those tiny little panels often sold as battery tenders are pretty useless on an automobile battery. They're even worse on the larger battery banks the typical RV has. When buying solar panels you will probably find that on a watts per dollar basis the larger the panel the better the price.
There's no reason not to put a larger panel on. A proper charge controller will keep your battery from being over charged no matter how large the panel is.

I would think the key is the disconnect switch. If there is one, 40 watts will work. Without it, I'd at least go with 100 watts to offset current draws from the fridge, radio, LP gas monitor, and other subsystems.

I'd aim for at least 40 watts. Anything smaller may not recharge the battery, depending on use. Do you have a disconnect switch on the battery?