Research - current projects

Long-term measurements

The Mont-Soleil solar power plant is one of the few large PV plants worldwide which has been in operation for more than 25 years with the originally installed solar panels. This plant therefore offers the possibility to directly investigate the aging of solar panels and other system parts. Due to the large number of installed modules, statistically relevant results can be gathered. For this reason, the plant forms a main pillar of the project "Long-term behavior of grid-connected photovoltaic systems" of the PV Lab at BFH in Burgdorf.

In order to be able to compare the energy production and the operating behavior of photovoltaic plants of different sizes and at different sites over a long period of time in a stringent manner, a standardized data evaluation must be the basis. For this reason Prof. H. Häberlin developed a methodology in the 1990s at the PV Lab in Burgdorf for the long-term measurements. This methodology has been consistently applied since then, which includes a detailed analysis of sporadic malfunctions (e.g. maximum power tracking error, (partial) shading or snow cover of the generator).

An important result of the long-term measurements is the quantification and explanation of the power degradation of the PV panels. It should be noted that even if a robust data base is available, the data evaluation requires, on the one hand, a very good understanding of the operating behavior of the PV system and, on the other hand, a sound knowledge of statistical methods. The corresponding work was therefore continued in 2018 at the PV Lab in Burgdorf.

Hence, based on the annual degradation of 0.13% found in the Mont-Soleil solar power plant, a very long service life of the solar modules (40 years or more) seems possible. However, experience with very old PV panels (e.g. the TISO-10 kW system of the Scuola universitaria professionale della Svizzera italiana SUPSI in Cannobio) shows a somewhat different picture. That is, the approximate linear degradation process supposingly turns into a non-linear, faster decay process after a certain age (typically> 30 years), so that an operating life of 40 years seems to be a very ambitious goal. It is therefore advisable for a PV operator to follow the "Solar Energy Market Survey" published annually by the Federal Office of Energy, which currently assumes a mean lifetime of a PV panel of 33 years.