pecos.pv module

The pv module contains custom methods for PV applications.

insolation(G, tfilter=None)[source]

Compute insolation defined as:

H=Gdt

where G is irradiance and dt is the time step between observations. The time integral is computed using the trapezoidal rule. Results are given in [irradiance units]*seconds.

Parameters:
  • G (pandas DataFrame) – Irradiance time series

  • tfilter (pandas Series, optional) – Time filter containing boolean values for each time index

Returns:

Insolation

Return type:

pandas Series

energy(P, tfilter=None)[source]

Convert energy defined as:

E=Pdt

where P is power and dt is the time step between observations. The time integral is computed using the trapezoidal rule. Results are given in [power units]*seconds.

Parameters:
  • P (pandas DataFrame) – Power time series

  • tfilter (pandas Series, optional) – Time filter containing boolean values for each time index

Returns:

Energy

Return type:

pandas Series

performance_ratio(E, H_poa, P_ref, G_ref=1000)[source]

Compute performance ratio defined as:

PR=YfYr=EPrefHpoaGref

where Yf is the observed energy (AC or DC) produced by the PV system (kWh) divided by the DC power rating at STC conditions. Yr is the plane-of-array insolation (kWh/m2) divided by the reference irradiance (1000 W/m2).

Parameters:
  • E (pandas Series or float) – Energy (AC or DC)

  • H_poa (pandas Series or float) – Plane of array insolation

  • P_ref (float) – DC power rating at STC conditions

  • G_ref (float, optional) – Reference irradiance, default = 1000

Returns:

Performance ratio in a pandas Series (if E or H_poa are Series) or float (if E and H_poa are floats)

Return type:

pandas Series or float

normalized_current(I, G_poa, I_sco, G_ref=1000)[source]

Compute normalized current defined as:

NI=IIscoGpoaGref

where I is current, Isco is the short circuit current at STC conditions, Gpoa is the plane-of-array irradiance, and Gref is the reference irradiance.

Parameters:
  • I (pandas Series or float) – Current

  • G_poa (pandas Series or float) – Plane of array irradiance

  • I_sco (float) – Short circuit current at STC conditions

  • G_ref (float, optional) – Reference irradiance, default = 1000

Returns:

Normalized current in a pandas Series (if I or G_poa are Series) or float (if I and G_poa are floats)

Return type:

pandas Series or float

normalized_efficiency(P, G_poa, P_ref, G_ref=1000)[source]

Compute normalized efficiency defined as:

NE=PPrefGpoaGref

where P is the observed power (AC or DC), Pref is the DC power rating at STC conditions, Gpoa is the plane-of-array irradiance, and Gref is the reference irradiance.

Parameters:
  • P (pandas Series or float) – Power (AC or DC)

  • G_poa (pandas Series or float) – Plane of array irradiance

  • P_ref (float) – DC power rating at STC conditions

  • G_ref (float, optional) – Reference irradiance, default = 1000

Returns:

Normalized efficiency in a pandas Series (if P or G_poa are Series) or float (if P and G_poa are floats)

Return type:

pandas Series or float

performance_index(E, E_predicted)[source]

Compute performance index defined as:

PI=EE^

where E is the observed energy from a PV system and E^ is the predicted energy over the same time frame. E^ can be computed using methods in pvlib.pvsystem and then convert power to energy using pecos.pv.enery.

Unlike with the performance ratio, the performance index should be very close to 1 for a well functioning PV system and should not vary by season due to temperature variations.

Parameters:
  • E (pandas Series or float) – Observed energy

  • E_predicted (pandas Series or float) – Predicted energy

Returns:

Performance index in a pandas Series (if E or E_predicted are Series) or float (if E and E_predicted are floats)

Return type:

pandas Series or float

energy_yield(E, P_ref)[source]

Compute energy yield is defined as:

EY=EPref

where E is the observed energy from a PV system and Pref is the DC power rating of the system at STC conditions.

Parameters:
  • E (pandas Series or float) – Observed energy

  • P_ref (float) – DC power rating at STC conditions

Returns:

Energy yield

Return type:

pandas Series or float

clearness_index(H_dn, H_ea)[source]

Compute clearness index defined as:

Kt=HdnHea

where Hdn is the direct-normal insolation (kWh/m2) Hea is the extraterrestrial insolation (kWh/m2) over the same time frame. Extraterrestrial irradiation can be computed using pvlib.irradiance.extraradiation. Irradiation can be converted to insolation using pecos.pv.insolation.

Parameters:
  • H_dn (pandas Series or float) – Direct normal insolation

  • H_ea (pandas Series or float) – Extraterrestrial insolation

Returns:

Clearness index in a pandas Series (if H_dn or H_ea are Series) or float (if H_dn and H_ea are floats)

Return type:

pandas Series or float