# PV System Models#

## Sandia array performance model (SAPM)#

 `pvsystem.sapm`(effective_irradiance, ...) The Sandia PV Array Performance Model (SAPM) generates 5 points on a PV module's I-V curve (Voc, Isc, Ix, Ixx, Vmp/Imp) according to SAND2004-3535. Calculates the SAPM effective irradiance using the SAPM spectral loss and SAPM angle of incidence loss functions. Deprecated since version 0.10.0. `inverter.sandia`(v_dc, p_dc, inverter) Convert DC power and voltage to AC power using Sandia's Grid-Connected PV Inverter model. `temperature.sapm_cell`(poa_global, temp_air, ...) Calculate cell temperature per the Sandia Array Performance Model.

## Pvsyst model#

 `temperature.pvsyst_cell`(poa_global, temp_air) Calculate cell temperature using an empirical heat loss factor model as implemented in PVsyst. `pvsystem.calcparams_pvsyst`(...[, R_sh_exp, ...]) Calculates five parameter values for the single diode equation at effective irradiance and cell temperature using the PVsyst v6 model. `pvsystem.singlediode`(photocurrent, ...[, ...]) Solve the single diode equation to obtain a photovoltaic IV curve. `ivtools.sdm.pvsyst_temperature_coeff`(...[, ...]) Calculates the temperature coefficient of power for a pvsyst single diode model. `pvsystem.dc_ohms_from_percent`(vmp_ref, ...) Calculates the equivalent resistance of the wires from a percent ohmic loss at STC. `pvsystem.dc_ohmic_losses`(resistance, current) Returns ohmic losses in units of power from the equivalent resistance of the wires and the operating current.

## PVWatts model#

 `pvsystem.pvwatts_dc`(g_poa_effective, ...[, ...]) Implements NREL's PVWatts DC power model. `inverter.pvwatts`(pdc, pdc0[, eta_inv_nom, ...]) NREL's PVWatts inverter model. `pvsystem.pvwatts_losses`([soiling, shading, ...]) Implements NREL's PVWatts system loss model.

 Calculate PV module efficiency using the ADR model. `pvarray.fit_pvefficiency_adr`(...[, dict_output]) Determine the parameters of the ADR module efficiency model by non-linear least-squares fit to lab or field measurements.