Voc or vmpp

[AranM0n3y88]

On the Mppt what does it look for voc or vmpp on the panel ?
which one u should add ur voltage voc or vmpp?

[Sunking]

You use Voc x 1.25 to make sure you do not exceed the maximum voltage input of the controller. You use Vmp for voltage drop calculations.

[inetdog]

Before the inverter turns on and actually starts working in the morning, when the sun hits the cold panels, the voltage at the inverter terminals will be the sum of the Voc values of the panels that are connected in series. And in cold weather that Voc value may be as much as 1.25 times the Voc at standard temperature that is shown on the panel label. As Sunking says, that must not exceed the maximum allowed input voltage on the controller or inverter specification.
When the device is operating, on the other hand, the voltage across the input terminals will be close to the sum of the Vmp values because the controller is trying draw enough current to drop the panel voltage from Voc to Vmp. These must also be corrected for panel temperature and on a hot day may be well below the Vmp shown on the panel label.
The sum of the Vmp values, corrected for temperature, should be above the minimum Vmp voltage limit of the controller.

[AranM0n3y88]

Thxz for the info



so I have 137.75 voc on 500 watts 100 each

22.4 x 1.25 x 3 =84 voc
21.4 x 1.25 x 2 = 53.75 voc
N I was going to add 1 more 100watt so I can have 6 (600watt) to charge my battery but my voc is 137.75 if I add 1 more I will get over 150voc right which I shouldn't do..so my ? now should I add 1 more panel or no 5 will charge 450ah Batterys

[inetdog]

You have not told us what your battery voltage is or what model CC you have.
With six panels one option is two parallel strings of three panels each. An MPPT CC should work perfectly well with that input unless some of the panels are partially shaded during the peak solar hours of the day.
Or you could have three strings of two panels each if that voltage is high enough for your CC.
Using prime numbers of panels (like 5 or 7 or 13) greatly limits your configuration options.

[Sunking]

Using prime numbers of panels (like 5 or 7 or 13) greatly limits your configuration options.

That is an understatement. It leaves you only one option, all in parallel and a lot of expensive fuses and combiners to buy.