Testing a solar cell against the seasons

At Ben-Gurion University, researchers ask what happens after the best efficiency measurement. Their work follows perovskite cells through changing light, heat and nights.

Select an underlined term for a short explanation.

How long does a solar cell last if its output falls in daylight and partly recovers overnight? Researchers at Ben-Gurion University's Sde Boker campus have been studying that awkward question. In a 2018 account, the university described work led by Mark Khenkin, Iris Visoly-Fisher and Eugene Katz to distinguish lasting damage from reversible daily changes. A single efficiency reading could not tell the whole story.

The work continues in Visoly-Fisher's materials group, which uses accelerated testing with concentrated natural sunlight alongside outdoor measurements. Its published research description says light intensity, temperature and environment can be controlled independently during exposure. That separation is important: if several stresses change together, it is difficult to identify which one is driving the change. An accelerated experiment needs a connection back to ordinary outdoor conditions.

A paper first published in November 2024 examined seasonal effects on particular perovskite solar cells. The researchers related measured stability to sunlight and temperature and combined outdoor analysis with indoor light cycling. They found that common lifetime indicators depended on climate. In this study, temperature was suggested to have a stronger influence on degradation than irradiance. The result concerns the tested devices and conditions, not a universal lifetime for all perovskites.

Consider T80, a measure of the time taken for performance to reach 80% of a stated reference value. It looks easy to compare two numbers, yet the seasonal study shows why their test conditions must accompany them. Reversible change makes the comparison more complicated still: recovery after a dark period is different from permanent loss. The clock, the environment and the measurement method belong with the headline result.

For Israel's solar-research community, this is a contribution to how technologies are evaluated, not simply another efficiency competition. Visoly-Fisher's group frames longer operational life as a route to more energy from a manufactured device. The practical question is whether a promising cell can keep delivering under a clearly described sequence of conditions. Following that evidence across seasons is slower than announcing a record, but it brings a future product's working life into view.