def __actual_voltage(self, photo_current, saturation_current, nominal_thermal_voltage, nominal_voltage, operating_temperature):
# TODO: I-V curve and P-V curve gets the sharp drop near open circuit voltage when irradiance dependence is taken into account
# Irradiance dependence:
single_voltage_irradiance_dependence = SingleVoltageIrradianceDependence(photo_current,
saturation_current,
self.shunt_resistance,
self.number_of_cells_in_series,
nominal_thermal_voltage)
irradiance_dependent_voltage = single_voltage_irradiance_dependence.calculate(nominal_voltage)
# Temperature dependence:
# Based on equation (24) of [1] but taking into account that the unit of temperature_voltage_coefficient is [V/ºC] instead of [%/ºC]. (Note: Different datasheets use either of these units):
return irradiance_dependent_voltage + self.temperature_voltage_coefficient * (operating_temperature - self.nominal_temperature)
def setUp(self):
self.open_circuit_voltage = 42.1 # [V]
self.photo_current = 3.506 # [A] Value for operating_temperature = 35 + 273 [K] and actual_irradiance = 900[W/m^2]
self.nominal_saturation_current = 1.680e-07 # [A]
# self.saturation_current = 4.00e-07 # [A]
self.shunt_resistance = 1862 # [Ω]
self.number_of_cells_in_series = 72
self.nominal_thermal_voltage = 0.0345
# self.operating_thermal_voltage = 0.0356
self.single_voltage_irradiance_dependence = SingleVoltageIrradianceDependence(
self.photo_current, self.nominal_saturation_current,
self.shunt_resistance, self.number_of_cells_in_series,
self.nominal_thermal_voltage)
class TestSingleVoltageIrradianceDependence(unittest.TestCase):
def setUp(self):
self.open_circuit_voltage = 42.1 # [V]
self.photo_current = 3.506 # [A] Value for operating_temperature = 35 + 273 [K] and actual_irradiance = 900[W/m^2]
self.nominal_saturation_current = 1.680e-07 # [A]
# self.saturation_current = 4.00e-07 # [A]
self.shunt_resistance = 1862 # [Ω]
self.number_of_cells_in_series = 72
self.nominal_thermal_voltage = 0.0345
# self.operating_thermal_voltage = 0.0356
self.single_voltage_irradiance_dependence = SingleVoltageIrradianceDependence(
self.photo_current, self.nominal_saturation_current,
self.shunt_resistance, self.number_of_cells_in_series,
self.nominal_thermal_voltage)
def test_calculate_irradiance_dependent_voltage(self):
voltage_estimation = self.open_circuit_voltage
irradiance_dependent_voltage = self.single_voltage_irradiance_dependence.calculate(
voltage_estimation)
# Since the given parameters are for the actual irradiance (900[W/m^2]) lower than the irradiance in Standard Test Condition (1000[W/m^2]), voltage should be less:
self.assertLessEqual(irradiance_dependent_voltage,
self.open_circuit_voltage)
# Since the result consistently gives 41.848808741740136 [V], use it as a assertion if the code is broken in the future modification:
self.assertAlmostEqual(irradiance_dependent_voltage,
41.849,
delta=0.001)
class TestSingleVoltageIrradianceDependence(unittest.TestCase):
def setUp(self):
self.open_circuit_voltage = 42.1 # [V]
self.photo_current = 3.506 # [A] Value for operating_temperature = 35 + 273 [K] and actual_irradiance = 900[W/m^2]
self.nominal_saturation_current = 1.680e-07 # [A]
# self.saturation_current = 4.00e-07 # [A]
self.shunt_resistance = 1862 # [Ω]
self.number_of_cells_in_series = 72
self.nominal_thermal_voltage = 0.0345
# self.operating_thermal_voltage = 0.0356
self.single_voltage_irradiance_dependence = SingleVoltageIrradianceDependence(self.photo_current,
self.nominal_saturation_current,
self.shunt_resistance,
self.number_of_cells_in_series,
self.nominal_thermal_voltage)
def test_calculate_irradiance_dependent_voltage(self):
voltage_estimation = self.open_circuit_voltage
irradiance_dependent_voltage = self.single_voltage_irradiance_dependence.calculate(voltage_estimation)
# Since the given parameters are for the actual irradiance (900[W/m^2]) lower than the irradiance in Standard Test Condition (1000[W/m^2]), voltage should be less:
self.assertLessEqual(irradiance_dependent_voltage, self.open_circuit_voltage)
# Since the result consistently gives 41.848808741740136 [V], use it as a assertion if the code is broken in the future modification:
self.assertAlmostEqual(irradiance_dependent_voltage, 41.849, delta = 0.001)
def setUp(self):
self.open_circuit_voltage = 42.1 # [V]
self.photo_current = 3.506 # [A] Value for operating_temperature = 35 + 273 [K] and actual_irradiance = 900[W/m^2]
self.nominal_saturation_current = 1.680e-07 # [A]
# self.saturation_current = 4.00e-07 # [A]
self.shunt_resistance = 1862 # [Ω]
self.number_of_cells_in_series = 72
self.nominal_thermal_voltage = 0.0345
# self.operating_thermal_voltage = 0.0356
self.single_voltage_irradiance_dependence = SingleVoltageIrradianceDependence(self.photo_current,
self.nominal_saturation_current,
self.shunt_resistance,
self.number_of_cells_in_series,
self.nominal_thermal_voltage)
