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Publications about Energy Technology / Renewable Energy

Cox A., Hupach U., Vaaßen W.:
Grid-Connected PV-Systems – Adequacy of PV-Modules and Inverters
15th Symposium for Photovoltaic Solarenergy, März 2000, Staffelstein, Germany

Abstract
Whether a grid-connected PV-system can produce an acceptable output or whether stable long-term operation is possible depends essentially on the system's main components, the solar module and inverter. In order to obtain statements on the adequacy and quality of the PV-modules and inverters which are available on the market, 10 inverters and 13 module types from various different manufacturers and of different construction types and ratings were purchased and subjected to an extensive comparability test in accordance with international standards.
Rating measurements and evaluations were carried out on the PV-modules with regard to the nominal rating and tolerances declared by the manufacturer. It became clear that the maximum ratings of the majority of the module types do not reach the nominal values declared by the manufacturer, but lie at the lower end of the stated tolerance range. A long-duration storage test with damp heat as well as a UV-irradiation test were carried out in order to examine the resistance to ageing of the PV-modules. Although the acceptance limit for type approval (IEC 61215) of –5% power degradation was complied with by all test specimens, there were distinct differences in the material stress and wear. Further examinations of the electrical safety, documentations, data sheets and labels, processing quality and termination techniques also revealed isolated weaknesses and mavericks, however on the whole it can be confirmed that the tested PV-modules are of a fairly high quality standard. It is a similar case with the inverters which were tested. The individual efficiency characteristics were determined and the power control behaviour of the test specimens was examined. Furthermore operation at high ambient temperatures, the automatic disconnection after a power failure, the current harmonic generated, the electrical safety and the electromagnetic compatibility were all examined. On the whole, the inverters tested also proved to be of a good technological standard. All appliances have fulfilled the demands made with certain limitations. However the examination of the electromagnetic compatibility revealed that most models exceed the limiting values of the underlying test standards. Furthermore there are still several improvements which could be achieved with regard to the electrical safety.

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