pvsyst cell temp docs for eta_m arg missing "area" from definition

[mikofski]

Describe the bug
the definition for eta_m says:

But I think this should actually be: (total DC power) / (poa_global * (total active module area))

To Reproduce
Steps to reproduce the behavior:

1. Go to https://pvlib-python.readthedocs.io/en/latest/generated/pvlib.temperature.pvsyst_cell.html#pvlib.temperature.pvsyst_cell
2. Look at pvlib.temperature.pvsyst_cell parameters
3. Scroll down to eta_m
4. See definition

Expected behavior
I think this should actually be: (total DC power) / (poa_global * (total active module area))

Screenshots

Versions:

• pvlib.__version__: v0.8.1
• pandas.__version__: na
• python: na

Additional context
see https://www.pvsyst.com/help/thermal_loss.htm

Effic  is the PV efficiency (related to the module area), i.e. the energy removed from the module. When possible, the PV efficiency is calculated according to the operating conditions of the module. Otherwise it is taken as 10%.

Does this mean that the Uc and Uv coefficients already take into account the active module area? but then eta_m will not be a number less than one, so I don't think so.

[cwhanse]

I think this should actually be: (total DC power) / (poa_global * (total active module area))

Agree. Good catch. Maybe "number of cells x cell area" would be more clear than "total active module area"

[KushalBeniwal]

@mikofski can I work on this issue?

[mikofski]

Yes, of course! thanks so much. If you need any help getting started check the contribution guide or you can at me here too.