Solar panel for storage

Start out with a 100w panel and a good 30+ amp controller. This is plenty to maintain your battery and you can add more panels/batteries later when you are ready for more solar.

If you plan to 'grow' the solar farm, make sure to get a controller that will handle all the panels that may be added.

The controller should have a temperature compensation sensor on the battery, and voltage sense wires are good, too.

Yes, I will be getting a controller too.
My intent is to start using this set up for maintenance of the battery, and gradually grow (getting more solar power)

Just as easy to mount 100 watt panel and not much extra $$.
Yes 100w will recharge and maintain your group 31.
You will need a controller.

I have one mounted on my propane tank cover. It is a small one maybe 2 or 4 watts. It puts out a max of 500mA. When my trailer would sit for a month the battery would be very weak. Now when it sits that long the battery always has a charge. I'm not going to say full charge, but it is enough to run the power tongue jack or the slide out if needed!

There are several low wattage SOLAR PANEL just designed for topping off the batteries when in storage. My JEEP had one laying inside the dash area and plugged into an active 12V socket. This did pretty good but was only a 10WATT model...

I would rather have a 20WATT or more small panel for that one battery... AMAZON has a several listed on their site...

If you expecting this to charge your battery in a three hour time frame this won't do that. This is just for leaving connected to you battery sitting in the high sun for longer storage time. It would be even better if you had a battery disconnect switch with only the small solar panel connected to the battery terminals.

I have multiple batteries in my battery bank and I switch them completely out while they are sitting on my trailer tongue. Then I will throw them on the trailer charger unit once a month for a few hours... When connected to shore power or a generator my trailer will re-charge these batteries to their 90% charge state in around three hours run time. Then I will totally disconnect them again...

The beauty of having your trailer parked at home...

Roy Ken

I wouldn't use anything less than a 100W module. As you select less watts the W/$ ratio increases. If you have 100W and are a moderate electrical user, the battery will be better maintained while in use.

For strictly battery maintenance 50 watts would suffice.

Depending upon cost difference, if it's not much, do the 100