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yurii avatar image
yurii asked

3 strings (5x panels) - which MPPT?

Hello!

I am new here so please forgive me if my question is silly ^^

We have thought situation with electricity in Ukraine, so I decided to install as many solar panels as possible to avoid blackouts.

As for now, I have 1 string with TrinaSolar 540W mono and planning to install 12 more panels,
but I can not find the exact model, so I will go with TrinaSolar 550W mono.
Totaly I will have 15 panels with 8.3kWt power )

MPPT calculator(xlsx file) shows me that 3 strings for 5 panels will work for MPPT 250/100, but with some warnings (more than 30% oversized PV generator) it is most overfull MPPT in a calculator.

So can you advise,
1) can I use MPPT 250/100 or EasySolar-II 48/5000/70-50 MPPT 250/100
it looks like they have the same tech specs MPPT....
2) or do I need to use MPPT RS 450/100 for my case
3) or I need to purchase an additional 5 panels (to have 20 in total),
re-design into 2 parts 2*5 and separate 2*5
and go with 2 MPPT 250/85

All this will be connected to 48V 10kWt battery and I'm going to purchase Victron Multiplus II 48V - 5000VA for the inverter


Thank you beforehand for advices.

MPPT ControllersMPPT SmartSolarmppt rsmppt calculator
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1 Answer
Alexandra avatar image
Alexandra answered ·

@Yurii

If the calculator says its ok, then it is ok. The spec is the same.

If it doesn't break the Voltage input limit at min temps, and does not go above the short circuit limit (70A in the 250/100)

The 450v mppt will just change the string voc not much else as they are both 100A models. However it does mke it easier to add strings that are different.

100A X battery voltage + 30% is a good way to size and array. (Divide by panel wattage for number of panels - rounded to the nearest config).

Example. 100a x 48v x 30% = 6240w (÷ 575w is 10.85 panels but for config reasons will be 10 since it cant be 11)

30% oversized is not always a bad thing. It depends on your expected irradiance and of you dont mind having power clipping at peak production.

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