Solar panels for battery charging

[JE Kerker]

We just purchased a 2019 Thor Quantum PD31 Class C. It came prewired for solar with connections on the roof. I want to use solar power to keep the house and chassis batteries charged while not being used.
I want to know if a 100 watt solar panel plugged into the existing connectors will keep all three batteries charged. I called Thor and they were not much help.
It has a Gopower controller built in.

[Long & Winding road]

Well congratulations. Nice rig. Post some pic if you can.

Look up the model # of your GO Power controller (should be written on the face plate. Im thinking that most of the factory installed solar controllers are limited to 10 amps? SO 100 watt (maybe 150) will be as large as you can go with the current controller??

100 watt should be enough to keep all 3 charged while in storage but if you boondock much you might want more. Not sure on what size batteres you have but most of the OEM are only rated around 80 amp hour each on the coach. So 100 watt would be sufficient for OEM but if you upgrade batteries later you might need more.

[JE Kerker]

Thank you. That is some of the most concise information I've received yet.

[Bob Denman]

Welcome to the Forum!
You can probably add more panels; as your needs change.

[jpmihalk]

Typically solar wiring goes straight to the house batteries and not to the chassis battery (used for the engine, etc.) Therefore unless the solar wiring is set up to also charge the chassis battery it isn't likely.

With that said, I don't think we have enough information without pictures to know what you have and where the wires terminate.

100 watts is good for keeping the batteries topped off in storage but will not charge your batteries for everyday usage. Your batteries will need some help from the generator (which you need for AC at minimum and maybe the microwave.) We have 400W of solar panels and they still don't always keep the batteries charged, but we also have a lot of electronics and a residential fridge so we use a lot of energy. Once you know what your energy budget is, you can size your solar array accordingly.

Best of luck, there are a lot of solar users here with experience.

[Bob Denman]

Originally Posted by jpmihalk

Typically solar wiring goes straight to the house batteries and not to the chassis battery (used for the engine, etc.) Therefore unless the solar wiring is set up to also charge the chassis battery it isn't likely.

It wouldn't be all that tough to add a small panel that is dedicated to the chassis battery anyway.

[scrubjaysnest]

I use 2 - 100 watt panels to maintain the cranking and two 105 Ah house batteries. Once the house batteries go above 13.1 volts the B.I.R.D will close the Trombetta relay and allow charging the cranking battery at the same time. For dry camping I have 300 watts of solar in a portable setup.

[HaRVey]

Our Thor Palazzo also came with the 100w solar. It has a GoPower 30amp PWM controller (~85% efficient) and a single 100w Polycrystalline panel (~75% efficient) and other post is correct that it provides minimal charge to the house batteries only.
I am adding a GoPower 680AE system (monocrrystaline panels, & MPPT controller both ~95% efficient) to power my 4, 100 ahr house batteries and moving the output of the factory system to the chassis batteries.

[Bob Denman]

Originally Posted by scrubjaysnest

I use 2 - 100 watt panels to maintain the cranking and two 105 Ah house batteries. Once the house batteries go above 13.1 volts the B.I.R.D will close the Trombetta relay and allow charging the cranking battery at the same time. For dry camping I have 300 watts of solar in a portable setup.

https://www.youtube.com/watch?v=bgiQD56eWDk