Upgrading our RV solar system

[mmays1]

Hello all. I am new to the site and would like a little advice. My wife and I started full time RVing this year and it is time to upgrade the solar in our rig. We have a class A and currently have a 140 W polycrystalline panel. This is connected to a SunSaver 20 PWM controller. I just purchased two lithium ion batteries (2 x 12V, 100Ah) for a total of 200Ah capability. I also just installed the Victron SmartShunt to monitor the batteries.

What I would like to do is install 2 x 200W monocrystalline panels and remove the 140 that I have. I am going to replace the charge controller with a Victron MPPT controller but not sure which one I will need. I am starting with 400 watts of panels but would like to have room to expand later. I am not installing an inverter at this time but possibly in the future.

Can someone let me know which controller would be best? I am looking at the Victron 100/30 or the 100/50. Which would allow for future expansion? Thank you in advance for the help. Mike

 

[MisterSandals]

2 x 200W monocrystalline panels

400W / 14V charging = 29A max charge rate

You will max out the 100/30 with 400W of solar.

 

[Casteil]

400W / 14V charging = 29A max charge rate

You will max out the 100/30 with 400W of solar.

Yep!

If you want to plan for future expansion you're either going to want a bigger controller that could handle significantly more PV voltage / charging amperage than you immediately plan to, or just plan for a second charge controller if you add more panels in the future. That might be the smarter route for a camper/rv rooof because it can be difficult to get a good series/parallel setup.

 

[deserthi]

I have a never used Victron 100/50 I could let go for $275 if your interested. Not sure if I am supposed to try to sell things but I do not need to sell it just trying to help out.

 

[chrisski]

From equinox to the shortest day of the year and back, I’ve never seen more than 420 watts from 600 watts of RV panels. Most of the time I peak around 300 watts.

A 100/30 will be good for 400 watts of flat RV panels. You may even be able to add another 200 watt panel after you collect data.

IME as mentioned earlier, an RV upgrade with more panels usually requires a second SCC. I have 3 SCCs for three different arrays.

 

[Doggydogworld]

How much do you want to expand? Even a 100/50 will only take you to ~600W with a 12V battery. At some point it makes sense to go to 24V.

Do you always park in full sun? If not you might want to keep that 140 panel plus a pair of long wires for ground-mounting away from the rig.

 

[mikefitz]

Go for the 100/ 30 for now with the two 200 watt panels in series. It's rare to get more than 60 to 70 % of panel power in a RV application, even if this occurs and technically is in excess of the controller maximum current, there is no problem. Under 'overpanel conditions' the controller just safely limits to maximum current output value.
Further expansion for a 12v system would be a second controller with two more panels. An alternative would be to consider a 24 volt systen where a 100/30 would allow 800 watts of panels

 

[mmays1]

Thank you all. This is very helpful information. I have some more thinking to do. It's great to have a place like this to ask questions. I'm sure I will have more questions as I progress.