This paper covers the behaviour efficiency of solar cells based on monocrystalline silicon when converting energy in temperature ranges from −170 °C to +100 °C.
Terrestrial equipment can reach temperatures up to −100 °C to +100 °C on the Earth’s surface but in space the temperature range increases
I (current)–V and P–V characteristics are discussed in terms of the theory of solids.
The open-circuit voltage dependence is approximately linear over a wide temperature range, but saturation occurs at temperatures around −150 °C, which is also explained in accordance with the theory of semiconductors.
The decrease in energy conversion efficiency with increasing temperature has a value of about 0.5%/°C throughout the whole temperature range possible on the Earth’s surface.
The electrical voltage of the PV modules will change depending on the temperature, in space these fluctuations increase as well.
Temperature changes cause changes in the Fermi energy level to change the open-circuit voltage and the electrical power supplied by the system will change.
Systems with concentrators of solar radiation can significantly increase the temperature of PV modules as well. Therefore, designers of a mission need to balance power and the higher intensity of radiation and the reduction of energy conversion due to energy change.
The paper suggests that thermal insulation or hybrid photo thermal designs can mitigate these issues
Measurements took place in a vacuum chamber to avoid contamination from humidity; the chamber pressure was about 2000 PA.
The source of radiation was a halogen incandescent lamp 12 V, power 20 W, angle 36°. The radiation intensity on the PV cell was 297 W m−2, which is less than the intensity of direct sunlight.
The paper states that in the liquid nitrogen-exchanger-thermally conductive paste-PV cell, there was a large temperature gradient.
1) The PV cell is not illuminated, a constant current of 0.2 A (Agilent source E3631A) flows through it, and the voltage on the PV cell is low. This voltage value is used to determine the PV cell temperature in a given measurement cycle.
2) The PV cell is illuminated, the transistor is closed, and open-circuit voltage Voc is measured.
3) The PV cell is illuminated, the transistor is opened and closed by a sawtooth signal (Agilent 33220A signal source), and the voltage values V and the current I on the I–V characteristics are measured.
4) The PV cell is illuminated, the transistor is fully opened, and current close to short-circuit current Isc is measured. Since a resistor is used to measure current, it is not possible to measure up to a short-circuit current
With increasing temperature, the maximum electrical power supplied by the PV cell at constant radiation intensity is reduced, and the efficiency of energy conversion is also reduced.
The paper states that the effect of temperature on PV energy conversion means that extreme solar radiation does not mean extreme yield from a PV power plant
The highest yields from PV plants are usually found in northern and colder aerials of the earth and at higher altitudes
For space missions the temperature fluctuation will need to be designed to ensure maximum efficiency for power systems.
The paper admits that while it tested the PV cell based on monocrystalline silicon in a range higher than that likely on earth in space missions the temperature can be much lower than -100 degrees.
Also due to the voltage being higher in lower temperatures this can also cause damage to space missions if not designed for.
The paper shows that at temperatures around −150 °C, saturation occurs, which was explained in accordance with the physical theory of semiconductors
The decrease in energy conversion efficiency with increasing temperature has a constant value of approximately 0.5%/°C over the entire temperature range.
Electronic inverters tend to be sensitive to overvoltage or undervoltage.
Changes in the Efficiency of Photovoltaic Energy Conversion in Temperature Range With Extreme Limits
IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 11, NO. 6, NOVEMBER 2021