pvlib.pvsystem.snlinverter¶

pvlib.pvsystem.snlinverter(v_dc, p_dc, inverter)[source]

Converts DC power and voltage to AC power using Sandia’s Grid-Connected PV Inverter model.

Determines the AC power output of an inverter given the DC voltage, DC power, and appropriate Sandia Grid-Connected Photovoltaic Inverter Model parameters. The output, ac_power, is clipped at the maximum power output, and gives a negative power during low-input power conditions, but does NOT account for maximum power point tracking voltage windows nor maximum current or voltage limits on the inverter.

Parameters
• v_dc (numeric) – DC voltages, in volts, which are provided as input to the inverter. Vdc must be >= 0.

• p_dc (numeric) – A scalar or DataFrame of DC powers, in watts, which are provided as input to the inverter. Pdc must be >= 0.

• inverter (dict-like) – A dict-like object defining the inverter to be used, giving the inverter performance parameters according to the Sandia Grid-Connected Photovoltaic Inverter Model (SAND 2007-5036) [1]. A set of inverter performance parameters are provided with pvlib, or may be generated from a System Advisor Model (SAM) [2] library using retrievesam. See Notes for required keys.

Returns

ac_power (numeric) – Modeled AC power output given the input DC voltage, Vdc, and input DC power, Pdc. When ac_power would be greater than Pac0, it is set to Pac0 to represent inverter “clipping”. When ac_power would be less than Ps0 (startup power required), then ac_power is set to -1*abs(Pnt) to represent nightly power losses. ac_power is not adjusted for maximum power point tracking (MPPT) voltage windows or maximum current limits of the inverter.

Notes

Required inverter keys are:

Column

Description

Pac0

AC-power output from inverter based on input power and voltage (W)

Pdc0

DC-power input to inverter, typically assumed to be equal to the PV array maximum power (W)

Vdc0

DC-voltage level at which the AC-power rating is achieved at the reference operating condition (V)

Ps0

DC-power required to start the inversion process, or self-consumption by inverter, strongly influences inverter efficiency at low power levels (W)

C0

Parameter defining the curvature (parabolic) of the relationship between ac-power and dc-power at the reference operating condition, default value of zero gives a linear relationship (1/W)

C1

Empirical coefficient allowing Pdco to vary linearly with dc-voltage input, default value is zero (1/V)

C2

Empirical coefficient allowing Pso to vary linearly with dc-voltage input, default value is zero (1/V)

C3

Empirical coefficient allowing Co to vary linearly with dc-voltage input, default value is zero (1/V)

Pnt

AC-power consumed by inverter at night (night tare) to maintain circuitry required to sense PV array voltage (W)

References

[1] SAND2007-5036, “Performance Model for Grid-Connected Photovoltaic Inverters by D. King, S. Gonzalez, G. Galbraith, W. Boyson

[2] System Advisor Model web page. https://sam.nrel.gov.