Adding Solar to a Motor Home

[bajajoaquin]

I found this forum from the mobile solar power website. On the pages describing the 400w systems there were two things that confused me.

1. there’s a difference between a 400w system and a 400w system with alternator charging. I’m looking at 200w but it didn’t mention alternator charging. Can I add a solar charge controller to my existing battery/12v setup or do I need to start from scratch? I’d like to charge while I drive.

2. the 400w system has a note in there that hooking up the panels in series would be preferred, but the controller won’t handle it. In order to allow for adding panels later and because I’m not sure how long my cables may have to run yet, I’d like to have the option of running in series. What would I need to change about the system? Is it as simple as getting a different controller?

I just bought the camper, so I don’t know the details yet it’s got an unidentified 12v battery for house power now. Depending on cost and the cost of other things I need to do, I’ll be upgrading that to either 2 6v or maybe a LiFePO4 (is that right?). I suppose I could run 2-12v in parallel if I really needed to conserve short term dollars. (Camper needs 7 new tires, belts, hoses and other delayed maintenance, cost TBD)

As for the size of the system, I haven’t done an audit, but my family of four was just fine in Baja for a week in a truck camper with a 64w panel run through the fridge (by previous owner) and a single battery. So we really don’t run much, but my wife would like to be a little less careful this time around. 200 should be plenty without spending money on capacity we don’t need.

 

[MisterSandals]

Can I add a solar charge controller to my existing battery/12v setup or do I need to start from scratch?

You can add several chargers to charge if you like.
What is your "existing battery/12v setup"?

What would I need to change about the system? Is it as simple as getting a different controller?

Connecting panels in series adds the voltages of the panels. The primary requirement/limitation of panels in series is keeping the array voltage lower than the charge controller max input voltage (plus some leeway to allow for lower temperatures which increase solar array voltages).
So getting a solar charge controller (SCC) with a higher max input voltage will allow more more panels in series.
Note that you can do a combination of panels in series and parallel to allow for bigger arrays and keep the array voltage within the limits of the SCC.

As for the size of the system, I haven’t done an audit, but

If you're not interested in an audit, then you're likely going to waste money by building the wrong system the first time. We see it all the time. You will learn more during the energy audit than just about any other stage in building your system. Without it, you're probably not ready to put together a solar system.

 

[bajajoaquin]

You can add several chargers to charge if you like.
What is your "existing battery/12v setup"?


Connecting panels in series adds the voltages of the panels. The primary requirement/limitation of panels in series is keeping the array voltage lower than the charge controller max input voltage (plus some leeway to allow for lower temperatures which increase solar array voltages).
So getting a solar charge controller (SCC) with a higher max input voltage will allow more more panels in series.
Note that you can do a combination of panels in series and parallel to allow for bigger arrays and keep the array voltage within the limits of the SCC.

If you're not interested in an audit, then you're likely going to waste money by building the wrong system the first time. We see it all the time. You will learn more during the energy audit than just about any other stage in building your system. Without it, you're probably not ready to put together a solar system.

That’s right. I forgot that you can add DC to DC and it’s not like AC where you need to be in phase. Thanks.

The current setup is a standard Jamboree setup. I don’t know much about it, but I’ve attached a few pictures here. Looks like a 12v interstate group 27. If I’m translating “reserve capacity” correctly, it’s 160AH or 80 useable. It’s got a 5/21 manufacturing date so I’d hate to just toss it but I’d like a bit more capacity, I think. My Lance has the same battery and it’s been fine with 64 watts and a bit of generator time when we vacuum mid week. All my other campers with multi-battery setups have been 6v in series or series/parallel combinations. I understand that two batteries in parallel might have balancing issues.

Anyway, I appreciate the help so far, and i thank you all in advance for any other insight.