Parallel connection of PV strings with different voltages

Solar Questions and Comments
1

Hi Guys,
I have an odd number (15) of panels and have connected them in series as 2 separate strings (8 and 7 panels). Can I connect these in parallel? If so, does this result in the amount of current generated being limited to the smaller (7 panel) string?

BTW the panels are all the same brand (Trina) and rating (450w).

I have tried to find an answer on the internet, but all of the articles I’ve found relate to connecting different voltage panels in parallel, not strings of panels.

Would appreciate your expert guidance on this, so I can figure out if it makes any sense to proceed with this approach.

Thanks

2

Hi again @chewface

Do you not have 2 MPPT inputs into your inverter? You don’t want to parallel two different strings, you will bring the higher performing string down to the lower performing one. Are all the panels facing the same direction, and angle etc?

Cheers
Marty

3

Hi Marty;

Unfortunately my charger-inverter (MPP PIP5048MKX) only provides a single PV input. So from your reply, it seems that it would be better to parallel 2 strings @ 7 panels and use the ‘odd’ panel for something else.

FYI the panels are all facing the same direction and mounted at same angle.

Thanks for your advice.

Brgds,
William

1 Like
4

Ok, and then I’m assuming if you put in all in series the voltage is too high?

Cheers

5

Yes the MKX has pv input limit of 500vdc. The Trina Tallmax model in my setup has a VoC of 49v.

6

You must match the two strings → 7 panels each. The last one is for a spare or a seperated solar-powered system.

7

Like the others have said, don’t parallel two different length strings.

If you try to parallel different strings the Inverter (MPPT) cannot track the optimum voltage (Vmp) of either string and the performance will reduce.

9

Hello! buddy well looking out to your issue in my my view when integrating 15 Trina solar panels (450W each) in parallel, with an 8-panel and a 7-panel string, bear in mind that the overall current is capped by the smaller 7-panel string. While voltage remains constant, ensure your inverter can manage the combined current output for your solar power system. It’s wise to seek advice from a solar professional to ensure optimal system performance and safety.