clipping off-mpp operating point calculation

[mikofski]

Feature request An algorithm that determines the off-mpp operating point for inverters that are clipping

Describe the solution you'd like Assuming that if the converted AC out is greater than rated AC (at the ambient temperature), then the inverter will increase the voltage until the AC output, what is the DC output, DC voltage, and inverter efficiency loss

Describe alternatives you've considered I scripted something really, REALLY basic, I don't suggest something as simplistic as this:

p_ac = pvlib.inverter.sandia(v_mpp, p_mpp, inverter)  # use MPP first time
voltage_test_range = (v_oc - v_mpp)/100.0  # divide excess voltage into 100 steps
v_dc = v_mpp
while p_ac > ac_rated:
    v_dc += voltage_test_range  # add a little
    i_dc = np.interp(v_dc, v, i)  # v and i are the full IV curve
    # NOTE: v must be monotonically increasing for np.interp to work!
    p_dc = v_dc * i_dc
    p_ac = pvlib.inverter.sandia(v_dc, p_dc, inverter)

But it would be better to redo this with a scalar root finder from scipy.optimize like brentq.

Also, it the AC rated power should be adjusted depending on the ambient temperature, but this could be separate.

Additional context Sorry, I couldn't find any related issues/prs? ICYMI: @abhisheksparikh

[cwhanse]

I agree, would be a nice feature. Somehow it should accept any of the inverter models, or, be some kind of extension within the existing functions so that a user doesn't have to choose to call an inverter function or this new function.

We could also open issues for:

• inverter temperature derating (would be easy if there is a source for the %AC power / degree C relationship)
• non-unity power factor operations (I think this is difficult, as it would require knowledge of how efficiency changes with power factor, which is not measured AFAIK).

[mikofski]

may be related to #1199 ?