Please help me decide

[Wwiaftm]

Hi everyone!

First setup and before I button everything down I was wondering what options I have. Currently 12 x 100w (cheap) flex panels with 2 viltron 100/50 mppts going into a 12v lithium battery bank. Ive posted a full sun power image below for what I was getting. I have 2 main questions I was hoping I could get some help with.
I have room for an extra 2 panels. One would fit fine at the rear and another just barley under the starlink dish in the front. It would be blocked by shade for some angles but open for most of the day. The main issue I see here that I didn't account for is the angle of the rounded roof.

The sides of the bus are rounded to the left and the right sides. With some help from a forum member I went with 3s2p but After a little testing I see the power levels with the different angles. I was thinking about going to 2s3p and adding fuses so that I could make left, center and right strings. It would also allow me to add the 2 additional panels.

1. Being that one of the additional panels will be in the shade 30% of the time I understand that these two panes will not produce during that time. Is it possible to run the shaded panel individually? Ive been trying to keep the voltages the same but just wanted to check and see if there was a trick. If that was possible I could add one spare to the front controller and one spare to the back controller balancing the load. Ideally 7 panels on the front controller and 7 panels on the back controller.

2. If I do make left, center and right strings on the same controller will this hurt anything? Parking headed north the left string would be low sun, the center would be full and the right would be full. So will the left string have any issues during this time or just produce less?

Any help or possible ideas would be greatly appreciated!

 

[Supervstech]

Keep us posted on lifespan of the panels.
Flexible panels have a low reputation on the forum.
Strings in parallel all need to be same voltage, when shaded, the string produces less wattage.

Make sure you fuse each string when going over 2 strings.

 

[JBertok]

It's good practice to leave at least a 10% margin when factoring both voltage and amperage limits of the MPPT to accommodate the potential of higher than rated PV output when they are cold and/or exposed to partly cloudy skies.

2S or 3S are both be fine as long as the combined rated open-circuit voltage "Voc" sum of a series string doesn't exceed the rated 100V DC maximum PV input of your MPPT. (I'd use a 90V limit with the above-mentions 10% margin factored in.) 12V PV panels probably have an open-circuit voltage close to 24V each would would be too close for a 4S configuration. If they have a Voc rating of 22.5V or less you could safely do 4S.

When considering parallel limits for your MPPT, you just have to keep the sum of the rated short-circuit current "Isc" from your multiple strings under the 60A input limit of your MPPT. (I'd use a 54A limit.) Fortunately you won't be coming anywhere near that limit of your MPPT.

For 14 of those, putting 6 on one and 8 on the other would work out easiest mathematically.
On MPPT1 you can do 3S 2P.
On MPPT2 you can do 4S 2P if the rated PV Voc <22.5V, or do 2S 4P if the rated PV Voc is higher than 22.5V.

When combining strings in parallel, you want them all oriented the same direction as a rule. You've got a curved roof so it's not going to possible to strictly follow that convention as you already know. Prioritize first the series strings - try to have every panel in a series string on exactly the same plane if possible. Then, try to parallel the series strings closest in angle. For example, the panels on the right side should not be at all on the same MPPT as the left ones. Distribute the center ones as close as you can to matching the side ones and their MPPT.

As Supervstech said about fuses on each paralleled series string, you might need blocking diodes too. Check the specs on your panels to see if they have diodes integrated.