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magielvdb

Solar string connection to Growatt Inverter 2 in series or 3 in series

Question

I would like some advise on how to connect the PV string to the MPPT of the inverter. The manual specification is 60 to 115Vdc for the PV array range and 145Vdc for PV array max Voc.
 
The PV pannels I want to use is 330W with Voc 47V and Vmp 37.5V per panel. I want to get the best possible power output from the inverter for charging as well as supplying load. Would 2 x pannels in series or 3 x pannels in series produce the best results. I plan to start with 6 panels and expand with time

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1 hour ago, magielvdb said:
I would like some advise on how to connect the PV string to the MPPT of the inverter. The manual specification is 60 to 115Vdc for the PV array range and 145Vdc for PV array max Voc.
 
The PV pannels I want to use is 330W with Voc 47V and Vmp 37.5V per panel. I want to get the best possible power output from the inverter for charging as well as supplying load. Would 2 x pannels in series or 3 x pannels in series produce the best results. I plan to start with 6 panels and expand with time

Good day my advise is to do 2 in series X3 strings reason being 3 in series its too closer to your MPPT Max I dont think its safe and total watts will be 1980W - 20% depends on your wiring you will probably get around 1500W on 6 panels, secondly on the load depends how big is your load but ones everything is connected you should be able to see if 6 panels are good for your load or not and you can add another string.

I forgot your last question on the best results in terms of 2 or 3 in series that's not really matters because your total watts will be the same weather 2/3 in series on what changes is VOC and AMP'S

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7 hours ago, magielvdb said:
Would 2 x pannels in series or 3 x pannels in series produce the best results.

2S would be best.

Voc of 47 x 3 = 141 V, and that's at 25°C. That's way past the specification, and even well past the 130 V where power will be reduced (derating begins). At 0°C, it's usually about 7% more voltage, that's over 150 V, which is over the never-exceed voltage of 145 V.

The now uncommon 60 cell panels are good to connect 3S, and in fact 2S is probably too low a voltage in some conditions.

My rule of thumb is don't connect any panels 3S if they are over 45 V Voc (at 25°C, as they are usually quoted). This is of course for the solar charge controllers with a 145 V maximum; some have 115 V max, and other models have 450 V max or more.

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12 hours ago, Coulomb said:

2S would be best.

Voc of 47 x 3 = 141 V, and that's at 25°C. That's way past the specification, and even well past the 130 V where power will be reduced (derating begins). At 0°C, it's usually about 7% more voltage, that's over 150 V, which is over the never-exceed voltage of 145 V.

The now uncommon 60 cell panels are good to connect 3S, and in fact 2S is probably too low a voltage in some conditions.

My rule of thumb is don't connect any panels 3S if they are over 45 V Voc (at 25°C, as they are usually quoted). This is of course for the solar charge controllers with a 145 V maximum; some have 115 V max, and other models have 450 V max or more.

Thank you valuable information because my worry was the small margin before exceeding the MPPT max limits

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