Toyhauler Solar Panel / Controller Best Configuration

[rvtyme]

I have been modifying an existing solar system that was factory installed on my large 5th wheel
Original configuration was (3) 190W GoPower Panels Voc(24.09), Isc (9.98A), GoPower 30amp PWM Solar Charge Controller, GoPower 1500 Watt Inverter (handles only the TVs, recliner, Samsung Residential Fridge, 4x 12v standard Flood batteries. Unit was factory installed May 2021.

I have replaced the (4) batteries with 3 206AH SOK Lithium in parallel 12V - total of 618AH @ 13.8V
I have replaced the 1500 Watt Inverter with a Multiplus-II 12V/120 to provide charging/invertering power to my 50amp
I have replaced the 30amp GoPower PWM Solar charger with a 100/30 Victron Solar Charge Controller connecting to the 3 rooftop panels as described above.
I have installed a CervoGX and Touch 50 panel.

My next step is to expand the solar panels and possibly expand the battery bank with another 206AH SOK.

I think my solar options are:
Expand the existing 570w by adding another 570w (3 * 190) for a total of 1140w. Upgrading the solar wiring to the roof and removing the 100/30 Victron Solar Charge Controller and replacing with a 150/100 Victron Solar Charge Controller. Installed 2S3P configuration for 12V.
I would sell the 100/30 SCC

Keep the existing 3 panels & 100/30 Victron SCC in place (I think the SCC is under size?) and add a separate SCC (Victron 100/50?) for the expansion panels giving me flexibility to put (3-4) 200W HighTec branded panels.

Pros/cons?

 

[rmaddy]

3 190W panels is 570W. On a 12V system that can mean up to about 45A of charge current. But when the batteries are at 13.5V it's 42A. And with the panels mounted flat you'd be lucky to ever see 40A. So yes, your 30A SCC is not making full use of your 3 190W panels. It can only make use of about 400W of the 570W. A 100/50 or 150/45 would allow you to make full use of those existing panels.

With 6 190W panels (1140W) you would get at most about 85A of charge current. Probably closer to 80A at most due to the flat mounting. So you could use the 150/85. No need for the 150/100.

If you wanted to keep the 3 190W panels and then add 3 or 4 larger panels with a 2nd SCC then that would work but you would still want to replace the 100/30 since you are losing a lot of potential power.

Take a look at Victron's MPPT sizing calculator. It lets you enter your own custom solar panel specs and it will tell you the best MPPT SCC to match.

MPPT Calculator - Victron Energy

MPPT Calculator - Victron Energy

www.victronenergy.com

Some quick math:

4 12.8V 206Ah SOK batteries is 10547Wh. Let's say you use 90% of that in a day (that's a lot). You now need to replenish 9492Wh. If you get 5 hours of solar then you would need 1898W of solar. Given the flat mount I would raise that to 2200W of solar. Some numbers to consider. Adjust based on your expected use case.

 

[Rbertalotto]

If you add three more panels, I'd go dual SCC. With 2 charge controllers you have redundancy. One controller fails you would not ruin your trip. And I'd upgrade the one you have as rmaddy suggested.

 

[chrisski]

Once you monitor those panels for production, ou can figure if many more can fit on that one Victron SCC.

I have a 30 amp controller for four 175 watt (700 watts total) panels with a VOC of about 10 amps each i have on my roof For my 24 volt system. So i could see 28 amps charging to the battery, which could max that out. There are of course the angled roof,vents, and air conditioners that cut that prodcuuction down. In a perfect day, it would push 470 watts, or 17 amps, far underneath the rating.

I decided to max the controller out. my Victron MPPT manual says i can add panel amperage input up to a point where the VOC of the panels slightly exceeding the SCC rating. There’s better numbers in the manual. I added two more 175 watt panels to that SCC, for 1050 watts total. Between adding those two panels and a few of weeks going by going from the shortest day of the year to the equinox, that same string now maxes the SCC out at a little over 800 watts, 30 charging amps for about four hours a day.

I do have a couple of other SCCs. One is for 600 watts of panels on the roof, and the other is for 900 watts of panels on the ground. you’d be surprised how much more power the ground panels produce total by aiming them east, south, and west throughout the day.

 

[rvtyme]

Thanks all for the responses... all in the planning!