pvlib.pvsystem.singlediode¶

pvlib.pvsystem.singlediode(photocurrent, saturation_current, resistance_series, resistance_shunt, nNsVth, ivcurve_pnts=None)[source]¶

Solve the single-diode model to obtain a photovoltaic IV curve.

Singlediode solves the single diode equation [1]

\[I = IL - I0*[exp((V+I*Rs)/(nNsVth))-1] - (V + I*Rs)/Rsh\]

for I and V when given IL, I0, Rs, Rsh, and nNsVth (nNsVth = n*Ns*Vth) which are described later. Returns a DataFrame which contains the 5 points on the I-V curve specified in SAND2004-3535 [3]. If all IL, I0, Rs, Rsh, and nNsVth are scalar, a single curve will be returned, if any are Series (of the same length), multiple IV curves will be calculated.

The input parameters can be calculated using calcparams_desoto from meteorological data.

Parameters:

photocurrent : numeric

Light-generated current (photocurrent) in amperes under desired IV curve conditions. Often abbreviated I_L.

saturation_current : numeric

Diode saturation current in amperes under desired IV curve conditions. Often abbreviated I_0.

resistance_series : numeric

Series resistance in ohms under desired IV curve conditions. Often abbreviated Rs.

resistance_shunt : numeric

Shunt resistance in ohms under desired IV curve conditions. Often abbreviated Rsh.

nNsVth : numeric

The product of three components. 1) The usual diode ideal factor (n), 2) the number of cells in series (Ns), and 3) the cell thermal voltage under the desired IV curve conditions (Vth). The thermal voltage of the cell (in volts) may be calculated as k*temp_cell/q, where k is Boltzmann’s constant (J/K), temp_cell is the temperature of the p-n junction in Kelvin, and q is the charge of an electron (coulombs).

ivcurve_pnts : None or int

Number of points in the desired IV curve. If None or 0, no IV curves will be produced.

Returns:

OrderedDict or DataFrame

The returned dict-like object always contains the keys/columns:

i_sc - short circuit current in amperes.

v_oc - open circuit voltage in volts.

i_mp - current at maximum power point in amperes.

v_mp - voltage at maximum power point in volts.

p_mp - power at maximum power point in watts.

i_x - current, in amperes, at v = 0.5*v_oc.

i_xx - current, in amperes, at V = 0.5*(v_oc+v_mp).

If ivcurve_pnts is greater than 0, the output dictionary will also

include the keys:

i - IV curve current in amperes.

v - IV curve voltage in volts.

The output will be an OrderedDict if photocurrent is a scalar,

array, or ivcurve_pnts is not None.

The output will be a DataFrame if photocurrent is a Series and

ivcurve_pnts is None.