I have been looking at the Victron MPPT calculator at https://www.victronenergy.com/mppt-calculator and seeing how my 10 Trina panels could be used with a Victron MPPT.
It seems that the calculator is adjusting for temperature variations and every time I think a string might fit a mppt, it sizes it up to a higher voltage unit than I would expect.
My panels run at 10 amps or less, Maximum Power Voltage-VMPP (V) 33.8, Open Circuit Voltage-VOC (V) 40.8
If I put 2 of these in series, it says I need a 150/45 MPPT to handle it. It says that the voltage of these panels will be 104.5V at -5 Celsius.
I looked over my logs during hot & cold weather this year and I never saw more than 375 volts for the series of 10 panels and that was during warm weather, getting a lot of solar. It seems to me if I do hit -5 C that it will be the middle of the night with 0 current.
I would also think that since it is an MPPT with a voltage maximum, that if the MPPT were searching along the voltage range to find an optimal current that it wouldn't search up to a voltage above its own specifications.
But what do I know, I think I would be inclined to size them in a 3S config so my estimated max of 37.5*3 panels would fit in a 150/45 system, but NO, the calculator recommends a 250/70 TR. I can't win.
It seems that the calculator is adjusting for temperature variations and every time I think a string might fit a mppt, it sizes it up to a higher voltage unit than I would expect.
My panels run at 10 amps or less, Maximum Power Voltage-VMPP (V) 33.8, Open Circuit Voltage-VOC (V) 40.8
If I put 2 of these in series, it says I need a 150/45 MPPT to handle it. It says that the voltage of these panels will be 104.5V at -5 Celsius.
I looked over my logs during hot & cold weather this year and I never saw more than 375 volts for the series of 10 panels and that was during warm weather, getting a lot of solar. It seems to me if I do hit -5 C that it will be the middle of the night with 0 current.
I would also think that since it is an MPPT with a voltage maximum, that if the MPPT were searching along the voltage range to find an optimal current that it wouldn't search up to a voltage above its own specifications.
But what do I know, I think I would be inclined to size them in a 3S config so my estimated max of 37.5*3 panels would fit in a 150/45 system, but NO, the calculator recommends a 250/70 TR. I can't win.
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