Fraunhofer Institute for Solar Energy Systems ISEThe "PV20plus"project supports operators of PV systems that are no longer eligible for EEG remuneration after 20 years in deciding on sustainable and profitable continued operation. What about the value, technical condition, performance, and safety of aging PV systems? To answer these questions reliably, we are developing a method for assessing the remaining service life and repowering potential of the systems, which can be carried out without interrupting operation.
Photovoltaics After 20 Years of Operation
PV20plus
PV system on the Dreisamstadion in Freiburg after the last expansion in 2004.
Initial Situation
The German Renewable Energy Sources Act (Erneuerbare-Energien-Gesetz, EEG) came into force in 2000, laying the foundation for the expansion of photovoltaics. The act created attractive feed-in tariffs for solar power, triggering an initial wave of PV installations. Also in the supply area of our project partner badenova,numerous systems were built – especially between 2004 and 2008 – that could be operated economically thanks to the EEG remuneration.
Today, around 20 years later, the first of these systems are no longer eligible for statutory subsidies. For many other system operators, the end of EEG remuneration is approaching in the coming years. This marks the beginning of a new phase for the use of solar power – with new challenges, but also new opportunities.
Annual PV capacity installed in Germany since the introduction of the EEG. In the years 2025 to 2028, around 1 MW of system capacity is expected to fall out of the EEG subsidy, after which this figure will rise sharply.
Objective
As part of the project, we are developing a practical decision tree to support operators in their assessment and planning. This is based on a comprehensive analysis of the system, with a particular focus on technical evaluation. A reliable method is being developed to assess the repowering potential and remaining service life of the PV system. The method should be carried out on site with minimal effort – ideally without dismantling modules and without interrupting plant operation – and should be able to be performed as part of regular plant maintenance. This will ensure a sound basis for decision-making for operators.
Typical PV system from the early days of the EEG, here at project partner badenovaWärmeplus in Freiburg.
Approach
Possible options for dealing with the PV system are:
- Continued operation of the system under current market conditions
- Partial or complete repowering to increase performance
- Evaluation of the current and future value of the system
- Second-life use of the modules after dismantling
The right decision depends on a variety of technical, economic, and ecological factors. These include, among others:
- The technical condition of the system (e.g. module performance, electrical safety, soiling)
- The effort and costs of possible conversions
- Existing and future marketing opportunities (e.g. self-consumption, market prices, new subsidy models)
In order to provide a well-founded assessment, we combine proven measurement methods from the laboratory and practice with new approaches from digitalization, automation, and optimization of on-site inspections. In a step-by-step process, initial findings are validated by scientifically sound additional measurements – for maximum decision-making quality.