solarenergy.solar_panels module

Functions for solar energy dealing with solar (PV) panels/modules.

class solarenergy.solar_panels.SolarPanels(geo_lon: float = 0.0, geo_lat: float = 0.0, tz: str | None = None, az: float = 0.0, incl: float = 0.0, area: float = 0.0, p_max: float = 0.0, eff0: float = 0.0, deff_dt: float = 0.0, year: float = 2015, t_coef: float = -0.005, n_refr: float = 1.43, inv_model: str | None = None, inv_sn: str | None = None, name: str | None = None)[source]

Bases: object

Dataclass containing solar-panel parameters.

area: float = 0.0

Surface area of solar PV panels (m2; typically 1.6m2 per panel)

az: float = 0.0

‘Azimuth’ of the panel normal vector (rad; 0=S, π/2=W)

deff_dt: float = 0.0

degrades to 90% after 20 years)

Type:

Linear degradation of efficiency factor over time (yr^-1; -5e-3

eff0: float = 0.0

Original efficiency of solar panels + inverter, at installation (0-1; e.g. 0.15 for 15%)

geo_lat: float = 0.0

Geographic latitude of the panels (rad; >0 for east of Greenwich)

geo_lon: float = 0.0

Geographic longitude of the panels (rad; >0 for northern hemisphere)

incl: float = 0.0

‘Zenith angle’ of the panel normal vector (rad; 0=horizontal, π/2=vertical)

inv_model: str = None

Model or type of the inverter

inv_sn: str = None

Serial number of the inverter

n_refr: float = 1.43

1.000293)

Type:

Refractive index of PV cover (typically 1.43; air

name: str = None

PV plant name

p_max: float = 0.0

Maximum electrical power of solar PV panels or inverter (kW)

t_coef: float = -0.005

PV temperature coefficient (/K; typically -0.005)

tz: str = None

Time zone where the solar panels sit (e.g. Europe/Berlin)

year: float = 2015

Installation year (e.g. 2015.25 for 2015-04-01)

solarenergy.solar_panels.pv_cell_temperature(temp_a, glob_insol, v_wind, temp_c_noct=45, eta_c_noct=0.15, t_coef=-0.0045, glob_insol_noct=800, temp_a_noct=20, v_wind_noct=1, tau_alp=0.9)[source]

Estimate the PV-cell temperature as a function of ambient temperature, insolation and wind velocity.

Parameters:

  • temp_a (float) – Ambient temperature (°C or K - ensure all temperatures use the same unit).

  • glob_insol (float) – Global projected insolation on PV cell (W/m2).

  • v_wind (float) – Wind velocity (m/s).

  • temp_c_noct (float) – Cell temperature for nominal operating cell temperature (NOCT; °C or K).

  • eta_c_noct (float) – Cell/module efficiency for NOCT (-).

  • t_coef (float) – Temperature coefficient for Pmpp and η_cell (/K).

  • glob_insol_noct (float) – Projected global insolation on the PV module for NOCT (W/m2).

  • temp_a_noct (float) – Ambient temperature for NOCT (°C or K).

  • v_wind_noct (float) – Wind velocity for NOCT (m/s).

  • tau_alp (float) – Tau alpha (τα): the optical transmission-absorption coefficient for the PV module (0-1).

Returns:

PV cell temperature (°C or K).

Return type:

(float)

Note

  • This follows Duffie & Beckman (2013).

  • NOCT stands for normal-operation cell temperature and concerns the specifications of the PV module for realistic conditions. If not available, use STC specs everywhere instead.

  • Note that all temperatures should be either in °C or K; they should not be mixed.

solarenergy.solar_panels.pv_efficiency(temp_c, eta_c_stc=0.15, t_coef=-0.0045, temp_c_stc=25)[source]

Compute the instantaneous PV effiency for a given cell temperature.

We assume that the efficiency varies linearly with temperature.

Parameters:

  • temp_c (float) – Temperature of the PV cell (°C or K).

  • eta_c_stc (float) – Efficiency of PV (+inverter if desired) for standard test conditions (STC) (0-1).

  • t_coef (float) – Temperature coefficient for P_mpp and η (/K; <0).

  • temp_c_stc (float) – Temperature of the cells under Standard Test Conditions (°C or K, same as temp_c).

Returns:

Efficiency of the solar cell.

Return type:

float

solarenergy.solar_panels.read_solar_panel_specs(cfg_file='.solar_panels.cfg', rel_to_home=True, to_rad=True)[source]

Read solar-panel specifications from a configuration file.

Parameters:

  • cfg_file (str) – Configuration file to read specs from (by default relative to home directory).

  • rel_to_home (bool) – File path/name is relative to home directory.

  • to_rad (bool) – Convert angles from degrees to radians (location, orientation).

Returns:

Dataclass of type SolarPanels containing the specifications.

Return type:

(SolarPanels)