add Ross temperature model

[cwhanse]

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A simple cell temperature model using only NOCT as a parameter.

[kandersolar]

LGTM

[wholmgren]

Looks good overall. Minor stuff below.

[adriesse]

Should this really be called a "Ross" model? It's just basic heat loss and NOCT conditions:

total_loss_factor  = 800 / (noct - 20)
heat_input = poa_global
temp_difference = heat_input / total_loss_factor
return temp_air + temp_difference

I wouldn't say this approach ignores the effect of wind but rather that it tacitly assumes a wind speed of 1 m/s.

[cwhanse]

Should this really be called a "Ross" model? It's just basic heat loss and NOCT conditions:

Agree that's what it is, but it needs a name, and others have cited it as Ross' model (author of the reference).

I wouldn't say this approach ignores the effect of wind but rather that it tacitly assumes a wind speed of 1 m/s.

good point.

[cwhanse]

change docstring

[wholmgren]

thanks @cwhanse!