Power output with PV SOL

Options
Solar Expert Posts: 27
Hello!

I am calculating the power output of an existing PV system with the formula below:

Pg=Pgfv*(G/Gstc)*[1-(YPm*(Tc-Tstc))]

This is the typical formula used to calculate the output power. My problem is that I need to check if this formula is the right one for my system, and for this I am using PVSOL. The results don't match, and I am using the same values for irradiance and Temperature.

Anyone know wich formula use PV SOL to calculate the output power?

Thank you!

Options
Re: Power output with PV SOL

Take out the G/Gstc

NOTE: I Got the G/Gstc wrong... Ignore.

That is the generic hot panel setting, and is upside down.

Pvfg should be the array marketing specification.

And multiply by around 0.95 for MPPT controller derating.

If this is a PWM controller, then all of this is wrong.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Options
Re: Power output with PV SOL

Tc is actual cell temp in degree C And may be 10-30 C above ambient temperatures.<br><br>Tstc should be 25C.<br><br>Forgive typing mistakes... Using phone.<br><br>-
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 27
Options
Re: Power output with PV SOL

Hi,

I know what the factors mean, but why should I remove the G/Gstc factor?

I realize that I made a mistake, the temperature factor should be like this: [1+(YPm*(Tc-Tstc))], where YPm is the variation coefficient of the power with the module temperature.

Anyway my doubt is if PVSOL use the same formula to calculate the output power or not... the results don't match...
Options
Re: Power output with PV SOL

What exactly is "G"?

And I made a mistake. I was thinking Gptc which is temperature corrected.

So what is G vs Pgfv?

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Options
Re: Power output with PV SOL

And the temperature correction now has the wrong sign... I think.

When Tcell goes below 25C or Tstc, you want the power output to increase.

Sorry for any mistakes.... Doing this on a 2" Phone screen.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 27
Options
Re: Power output with PV SOL

G is the Global irradiance that reach to the modules, and Pgfv is the maximum power of the module in STC (nominal power)
Options
Re: Power output with PV SOL

Ok with g/gstc.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 27
Options
Re: Power output with PV SOL

ok, but could you confim me if the temperature factor is [1+(YPm*(Tc-Tstc))] or [1-(YPm*(Tc-Tstc))]??

I am not sure at all..
• Solar Expert Posts: 1,973 ✭✭✭
Options
Re: Power output with PV SOL
JavierOL wrote: »
ok, but could you confim me if the temperature factor is [1+(YPm*(Tc-Tstc))] or [1-(YPm*(Tc-Tstc))]??

I am not sure at all..
Run some test numbers and verify it for yourself; power goes down as temperature increases.