About 20 years ago, more than 900 schools spread all over Germany have received various grid connected PV systems of about 1 kW. Some years after the start of the promotion program, it has become clear, that for a successful operation some monitoring, supervision and appropriate reports would be necessary. Thus, a central coordinator has been installed. The task of the coordinator was as well to collect operation data, i.e. monthly yields, information about malfunction and to generate out of these data a report to send to the schools. This monitoring started in the year 1998. As the first PV systems have been installed in 1994, now operation results are available in a time span of 20 years for several hundred grid-connected PV systems in schools. Additionally investigations about the technical state of the components for randomly selected PV systems have been organized.

Untersuchung von Alterungseffekten bei monokristallinen PV-Modulen mit mehr als 15 Betriebsjahren durch Elektrolumineszenz- und Leistungsmessungen (2013)
Degradationseffekte durch Umgebungsbedingungen und das Langzeitverhalten von PV-Modulen sind über die letzten Jahre immer wieder Gegenstand von Untersuchungen gewesen. Optische Inspektion, Elektrolumineszenz- und Leistungsmessungen stellen dabei etablierte Hilfsmittel zur Untersuchung sowie zur Qualitätssicherung dar. Ziel dieser Veröffentlichung ist es, den Zustand von monokristallinen Modulen nach 15 und mehr Jahren Betrieb darzustellen.

Energy Yields of PV Systems – Comparison of Simulation and Reality (2008)
Simulation of PV systems is an important feature to predict mainly the yield but also the operational behaviour. How accurate are the simulation results? Thus the purpose of the work is to demonstrate the differences between simulation and reality. In a first step, three 1 kW PV systems coming from the solar promotion “Sun at School” have been investigated. Measured yields were available for many years. The software tools PVSYST and PVSOL have been applied to simulate the systems. In a second step, the yields of the 1016 kW PV system on the New Trade Fair Centre in Munich – which went in operation in 1997 – has been simulated using the block oriented simulation system INSEL. Simulation of two cases on the basis of measured irradiance data in the generator plane and ambient temperature data are leading to best simulation results. The total annual deviation between simulation and measurement is + 5,2 % in case of the fit with measured module data and – 1,4 % for the data sheet case. Of course, this does not mean that the data sheet approach is more accurate since cable losses, mismatch losses etc. have not been considered at all.

Degradation Measurements Of Aged PV Modules (2007)
Degradation measurements of aged PV modules with an operation time of about 8 to 12 years have been carried out. Only crystalline modules have been investigated. It will be distinguished between two groups. The first group of modules is coming from the photovoltaic promotion program “Sun at School” and from two larger PV plants in southern Germany. All they went in operation between the years of 1994 and 1997. No reference ist available for this group. The second group of modules is coming from the 1 MWP PV system Munich Trade Fair Centre, they were installed in 1997. For them a reference – non illuminated modules – is available. Within the first group, some faulty modules have been detected. It can be stated, that after 8 to 12 years of operation no module reaches its nominal power. This effect can come from degrada- tion, but can also come from the fact, that the original nominal power was considerably smaller than the value on the label. After nearly 8 resp. 9 years of operation, the modules of the 1 MWP PV system on the Munich Trade Fair Centre show degradation values of 2.4 up to 4.0 %. The measured output power of the “dark” modules at STC is nearly the nominal power, thus these modules serve as a reference.

Sonne in der Schule: Betriebsergebnisse aus den Programmen in Bayern, Sachsen und Norddeutschland (2005)
Beitrag auf dem PV-Symposium in Bad Staffelstein 2005

Sun at School – SONNEonline

Results of Two Photovoltaic School Promotions [Beitrag in englischer Sprache zur internationalen PV-Tagung „From PV Technology to Energy Solutions“ in Rom (7. – 11.10.2002)]