Two Questions for the seasoned pros of this great forum

[Mike90250]

As long as strings are SHADED equally (all shade, no shade) they should be able to be combined to the limits of a single MPPT channel.

If there is any difference in illumination or heating of the panels, you will get more efficiency with dual MPPT. ( in my opinion )

[scrambler]

Hi there, I have the following two questions if anyone has the answer.

1- Thermal expansion gap between panels:

Installation usually calls for at least 3/8” between panels to allow for thermal expansion and venting.

Usually mounts create the space between panels in the same row, so it is mostly about leaving a gap between rows.

I was wondering if anyone had actually measured the space between rows in the winter early morning and in the hottest hours of a summer day, and noticed an actual change, and if so how much?


2- Combining Strings in parallel.

Let say you have 20 panels in two strings of 10 (panels 33V Vmp and 9.5Amp Imp). This means each string has a max of 330V and 9.5 Amp, and if they were to be combined in parallel, the result would have a max of 330V and 19Amps.

Assuming a string inverter with two Mppts, each being able to accommodate the full values, Would the best configuration be to use one string on each Mppt, or to combine them on a single Mppt?

Does combining them reduces the efficiency of the system, improves it, or makes no difference?

Side question: If every panel has a Tigo TS4-R optimizer, does that change the above in anyway.


Thank you for your input