AC power output at night

[pepe82sh]

Hi Community,

I've been attempting to simulate my PV system (that is about to be installed) with pvlib. I've succeeded by utilising fit_sandia for the inverter and fit_desoto for the module parameters. Yet the output suggests that whenever I have no power on the DC side (at night), I have 39.268768W available on the AC side. I honestly have no clue why that would be the case. Has anyone else witnessed this behaviour for any circumstances?

I'd assume it's the inverter model, which is a Kostal G3 S 7kW, and this is how I defined it:

rated_power = 7000
self_power_consumption = 3.5
inverter_values = [(140, "Vmin", 490, 436.1),
                   (140, "Vmin", 1400, 1320.2),
                   (140, "Vmin", 2800, 2682.4),
                   (140, "Vmin", 4200, 4040.4),
                   (140, "Vmin", 5600, 5387.2),
                   (140, "Vmin", 7000, 6741),
                   (650, "Vnom", 490, 442.96),
                   (650, "Vnom", 1400, 1330),
                   (650, "Vnom", 2800, 2724.4),
                   (650, "Vnom", 4200, 4107.6),
                   (650, "Vnom", 5600, 5488),
                   (650, "Vnom", 7000, 6862.1),
                   (800, "Vmax", 490, 426.3),
                   (800, "Vmax", 1400, 1323),
                   (800, "Vmax", 2800, 2702),
                   (800, "Vmax", 4200, 4082.4),
                   (800, "Vmax", 5600, 5460),
                   (800, "Vmax", 7000, 6832)]
dc_voltage = pd.Series([val[0] for val in inverter_values])
dc_voltage_level = pd.Series([val[1] for val in inverter_values])
ac_power = pd.Series([val[2] for val in inverter_values])
dc_power = pd.Series([val[3] for val in inverter_values])
inverter_model = fit_sandia(ac_power, dc_power, dc_voltage, dc_voltage_level, rated_power, self_power_consumption)

any hints would be greatly appreciated.

[pepe82sh]

Ok, shit in -> Shit out. I've translated the inverter efficiency table incorrectly. In case anyone on the internets is stumbling on this, these are the more correct parameters:

    inverter_values = [(140, "Vmin", 490, 550.6),
                       (140, "Vmin", 1400, 1484.6),
                       (140, "Vmin", 2800, 2922.8),
                       (140, "Vmin", 4200, 4365.9),
                       (140, "Vmin", 5600, 5821.2),
                       (140, "Vmin", 7000, 7269.0),
                       (650, "Vnom", 490, 542.0),
                       (650, "Vnom", 1400, 1473.7),
                       (650, "Vnom", 2800, 2877.7),
                       (650, "Vnom", 4200, 4294.5),
                       (650, "Vnom", 5600, 5714.3),
                       (650, "Vnom", 7000, 7140.7),
                       (800, "Vmax", 490, 563.2),
                       (800, "Vmax", 1400, 1481.5),
                       (800, "Vmax", 2800, 2901.6),
                       (800, "Vmax", 4200, 4321.0),
                       (800, "Vmax", 5600, 5743.6),
                       (800, "Vmax", 7000, 7172.1)]