Different panels on 150/100 Mppt sets?

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marcel-solar-spain asked Oct 10, '21

Different panels on 150/100 Mppt sets?

Hi fellow solarians,

I've got a Easysolar with built in 150/100 mppt.
The mppt has 3 sets of MC4 connectors.

I had the setup running the last 3 years on 4 LG NEON 320W panels (LG320N1K-V5).
Wired in P/S combo.
Worked excellent. But now i'm rebuilding the house and need more power.

So i'd like to add 8 more panels on the other two available sets and get almost 4 KWH on a great day!

Problem is the LG's are very hard to get in Spain, plus it's an older model and they only sell the 330 or 340 types.

My question is can i put in 8 * 340W panels on the other sets in the same P/S combi setup or do i need panels with the exact same specs as my original 4 LG's?

If other brands and/or other W's are also possible it's a cheaper and better option (I can wire in series and get more V.)

Any tips or advice is greatly appreciated.

Cheers!

MPPT Controllers Solar Panel solar sizing

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Alexandra answered · Oct 10, 2021 at 04:03 PM

@Marcel_Solar_Spain

It would work. They may perform a little lower than their rating though.

To make the best of the situation, aim to get the voc as close as possible to your existing string. And of course panel wattage.

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Answer 1 · 2021-10-14T13:35:36Z

marcel-solar-spain answered · Oct 14, 2021 at 01:35 PM

Hi Alexandra, Thanks for your reply.

Would it be possible to add. 400, or even 500 watt panels, as long as the VOC is 40.8 (STC)?

So, my old panels on set 1: 4 *320W P/S
Set 2: 2*500W (40.8Voc)
Set 3: 2*500W (40.8Voc)

Or should i stay as close to my current 320W panels as possible?

Thanks again.
Marcel

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Answer 2 · 2021-10-17T00:25:53Z

Mike Dorsett answered · Oct 17, 2021 at 12:25 AM

As long as you don't exceed the Maximum power for the tracker - which depends on the battery voltage - by more than 15 - 20%, and the VOC of the strings match to within 5%, i.e.+/-6V for a 120V string ( 3 series), the panel powers of different strings do not need to match.

Theoretically the orientation of the strings should be the same, but I think that as long as the panels within the same strings are in the same plane you are good to go. What happens with different orientations in parallel is that the string with the highest illumination does all the work, and the other strings contribute less than expected, or less than if they were on a separate tracker.

BTW, 40.8V looks low for a 500W module: I wold have expected 45 - 48V... do check that this is not the max power voltage.

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marcel-solar-spain commented · Nov 23, 2021 at 05:56 PM

Thanks Mike, So my battery voltage is 51.2 and i have 3 of them (trying to buy a fourth one which is almost impossible). My 4 current panels per set are connected in series/parallel and the other 2 sets will be too. So if i stay in the 5% range i will be fine?

Cheers,

Marcel

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