Research project started at ZSW to repair and reuse photovoltaic modules

16. November 2023

It not only works for smartphones, but also for photovoltaic modules: With the start of the RENEW project, the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) and several partners are researching the repair and reuse of photovoltaics ( PV) modules. The three-year project is funded by the Federal Ministry for Economic Affairs and Climate Protection (BMWK). The aim is to test used PV modules more effectively and with high throughput and to develop new repair options in order to reduce the amount of PV modules disposed of. In the project, the project partners are defining new standards for the characterization of used PV modules. This offers high recycling potential. In addition to ZSW, the companies 2nd Life Solar, HaWe Engineering and ELMED Dr. Ing. Mense involved.

The acronym RENEW stands for the repair and reuse of PV modules. A look into the future shows that the global PV expansion goals will not only require new modules on an ongoing basis. It is also important to keep the modules in operation for as long as possible, which increases sustainability and reduces the costs of PV electricity.

Due to the rapid technological development of module technology in the last ten years alone, new modules are attractive for power plant operators for economic reasons due to the higher output in the same area. In so-called repowering, old modules are dismantled and replaced with new, more powerful modules, even though they would still be operational. The extensive experience with field-aged modules from the ZSW solar laboratory Solab shows that the majority of the modules hardly suffer any loss of performance even after more than 20 years of operation, especially in locations with a temperate climate such as Central Europe. According to the experiences of the project partner 2nd Life Solar, around 70 percent of the sorted modules are currently still operational. In order to further improve these numbers, various repair solutions are also being qualified in the project.

In addition, the amount of old modules that are disposed of properly does not correspond to the expected quantities and the question arises as to where these modules end up as untested electrical waste – according to 2nd Life Solar GmbH from the waste recycling industry. Their research team is therefore based on the principle of the circular economy. Before the modules are recycled, their functionality is checked. If this is the case, the module can be reinserted directly.

The longevity of PV modules, but also the ability to repair and test after years of use, are cornerstones for the future. Since many manufacturers are no longer available to customers at the end of a module’s lifespan, the project recognizes the great need to improve repair and reuse options throughout Germany.

The demand for used modules is high
Maximilian Engel, project coordinator of the RENEW project at ZSW, summarizes: “The market for used modules is growing rapidly because the expansion goals for photovoltaics are ambitious. To do this, we need every module – whether new or used – in the company until it is no longer operational. Even though I am pleased about the current high pace of expansion, we must not neglect the sustainable use of the resources used. To do this, it is important to qualify used modules efficiently and thus cost-effectively with a high throughput and, if necessary, repair them in order to keep them in operation.” In addition to their use in smaller stand-alone systems and as balcony power plants, there is also the possibility due to the high number of field-aged modules to equip entire PV parks with used modules.
Germany-wide scaling planned
A project partner that already carries out quality testing of used photovoltaic modules and resells field-aged modules after extensive testing is 2nd Life Solar. In order to meet increasing demand, the company wants to further expand its concept. Such scaling requires reliable process standards for mobile and stationary quality testing. By upscaling the processes, the project partners hope to reduce the amount of untested electronic waste that is transported abroad.

In order to optimize the test, the project team cooperates with ELMED Dr. Ing. Mense GmbH. ELMED specializes in testing devices from the coating industry and can therefore carry out tests with the lowest material load on the coating. HaWe Engineering GmbH will use the project results in various PV systems in a field study in order to make it possible to qualify used modules on site.

The basis is a catalog of criteria for older PV systems
RENEW’s project coordinator is ZSW. With the Solab solar laboratory, it has many years of experience with field-aged modules. The tests carried out at ZSW cover the degradation of PV modules, backsheet analysis and material analysis. The project team also draws on the results of a previous project: At the end of the project, examinations of damaged back foils resulted in a comprehensive catalog of criteria to evaluate module defects. Through RENEW, the ZSW wants to increase the quality of the testing of old modules and make it scalable – and thus make the use of PV modules even more sustainable.

About the ZSW
The Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) is one of the leading institutes for applied research in the major topics of the energy transition: photovoltaics, wind energy, batteries, fuel cells, electrolysis, eFuels, circular economy, policy advice and the use of AI for process and system optimization. Together with industry, we pave the way for new technologies to enter the market. More than 300 colleagues and around 100 research and student assistants work at the ZSW locations in Stuttgart and Ulm. The ZSW also operates a test field for wind energy and another test field for PV systems. We are a member of the Baden-Württemberg Innovation Alliance (innBW), an alliance of ten business-related research institutions.

Julia Fromm, Center for Solar Energy and Hydrogen Research (ZSW),
Tel.: +49 711 7870-278,

Axel Vartmann, PR-Agency Solar Consulting GmbH,
Tel.: +49 761 380968-23,,