[need help] pv output

corazon

halo, i'm new on this technology, i want to ask is it possible to find the output of pv module if its not connected to load?
according to Pmax=Vm.Im or Pmax=Voc.Isc.FF
from multimeter i can get the value of Voc and Isc but i'm stuck how to find the value of Vm and Im
please help me, thanks before

Shawn-H

I need to know more about the components and what you have charge controllers load diversion devices things like that

inetdog

corazon said:

halo, i'm new on this technology, i want to ask is it possible to find the output of pv module if its not connected to load?
according to Pmax=Vm.Im or Pmax=Voc.Isc.FF
from multimeter i can get the value of Voc and Isc but i'm stuck how to find the value of Vm and Im
please help me, thanks before

You cannot reliably tell the output of a PV module (cell or panel?) without a variable load. The only things you can measure are Voc and Isc. It is true that IF you know the fudge factor (FF?) for a particular cell design you can estimate the output as Voc x Isc x FF.

As a rule of thumb for crystalline silicon cells Vmp is about 80% of Voc. The ratio between Isc and Imp will vary more widely.

To actually measure Vmp and Imp you need to attach a variable resistance load and tune it to the Maximum Power Point before measuring. Or hook it up to an MPPT inverter or to a CC charging in Bulk mode into a depleted battery bank. And the whole time you need to use a calibrated reference light source or have the panels facing directly toward the noon sun on a clear day. Even in the latter case the panel temperature will be an uncontrolled variable.

corazon

thanks a lot @inetdog , i nearly understand,  so if  my panel not conected to any load (inverter, solar charge controller or variable resistance load), and i only measurimg the Voc and Isc with multimeter, i cant calculate Pout of my pv module (panel) right?
btw what is the difference between Pmp and Pout? 

oil pan 4

If you are only working with Voc times Isc you will get an unrealistic amount of wattage.

Dave Angelini

You should get a pretty close reading of power out with Isc.  Close enough for government work...

corazon

 

from equation 5.12, i need value of Imp and Vmp to get the FF (fill factor) value.
if i cant measure the Vmp or Imp since my PV panel not connected to any load, can i use eq 5.13 to get the FF? 

thanks before