Documentation Question on Soiling

[kurt-rhee]

Hello what is the timestep of this soiling sequence, is it monthly?

[cpaulgilman]

Yes, the soiling loss input is an array of 12 percentage values, one for each month of the year. During a simulation, the beam irradiance for each time step in a month is multiplied by the soiling loss for that month.

[kurt-rhee]

Thank you for the information!

[kurt-rhee]

I have another theoretical question, how does PVwatts v7 calculate bifacial gain if I don't specify albedo in model.SolarResource?

I see that changing bifaciality changes my energy value.

Thanks,

Kurt

[cpaulgilman]

Hi Kurt,

If you do not provide albedo data in the weather file, pvwattsv7 (and pvsamv1 and earlier versions of pvwatts) use a default value of 0.2 for all time steps. You can see that in the pvwattsv7 source code around Line 735:

https://github.com/NREL/ssc/blob/develop/ssc/cmod_pvwattsv7.cpp

Thanks,
Paul.

[kurt-rhee]

Very helpful, thank you Paul