Israeli researchers resolve temperature effects on PV device performance

16 Jun 2023

Combined thermoradiative and thermo photonic cells are more efficient in converting sunlight to electricity.

Photovoltaic technology is indispensable for our ability to mitigate climate change. Nonetheless, more than 70% of the energy made available to us by the sun is wasted in conventional photovoltaic cells. There is little hope for sustainable technological advancement without addressing this issue.

The operational temperature is a critical factor in a solar cell's ability to convert sunlight to free energy. Accordingly, much research has been directed toward understanding the temperature effects in the efficiency of photovoltaic solar cells. Surprisingly, however, little is known about what this temperature would end up being.

In a paper entitled “Effect of maintaining a fixed ambient temperature on the evaluation of photovoltaic device performance,” published in Physical Review Applied last week, researchers from the Ben-Gurion University of the Negev Solar Energy Research Center, answer this question by balancing the photon and energy rates of the photovoltaic effect.

New approach

Their new approach theorizes a fluctuation in temperature in response to the heat produced from light absorptance and the connection to a fixed temperature environment, whereas present analyses are based on the premise that the cell temperature would remain fixed regardless of its operational conditions.

“This paper’s solid theoretical grasp is a prerequisite for significant technological advancement. Therefore, illuminating the hidden aspects of the photovoltaic effect contributes to realizing disruptive concepts, such as thermoradiative and thermophotonic cells,” said lead author Dr. Avi Niv.

Thermoradiative and thermophotonic cells are advanced conceptions of photovoltaic energy conversion that enable industrial processes’s waste heat recovery (thermoradiative) or are more efficient in converting the sun's radiative energy flux to electricity (thermophotonic).

Paper abstract

The Abstract from paper in Physical Applied Review reads, “We analyze the photovoltaic effect while assuming a fixed ambient temperature and a varying system temperature rather than using the standard fixed system temperature–based approaches. We do so by complementing the photon rate balance equation (detailed balance, circuit model) with the power balance equation of the system.

“As a result, a simple approach capable of treating any photovoltaic system emerges. Accordingly, we study the potential-dependent current and temperature of solar cells and thermoradiative power generators. We show that the optimal band gap of a solar cell depends on its heat-transfer coefficient and that its efficiency may rise or fall as solar concentration increases, depending on its ability to dissipate heat.

“We also identify where the cell’s efficiency and temperature turn from a conductive and/or convective-dominated cooling regime to a radiative-dominated one. For the thermoradiative case, we show that its power decreases when heat intake is suppressed and study the degrading effect of nonradiative recombination on this power production scheme. The proposed model converges to the known fixed system temperature–based approaches when an infinite ability to transfer heat is considered.”