Thermal and electrical effects caused by outdoor hot-spot testing
in associations of photovoltaic cells
Progress in photovoltaics: research and applications, (2003)DOI: 10.1002/pip.490
Abstract
An outdoor test facility has been prepared for the evaluation of
the thermal and electrical effects caused by outdoor hot-spot testing
in crystalline silicon modules. Five module types have been subjected
to an outdoor test programme with the purpose of analysing their
hot-spot endurance. The worst-case cell in each module type has been
detected by laboratory characterisation under reverse-bias operation
of all the individual cells included in the module. These cells,
encapsulated within the module, have been operated at different shading
fractions with bypass diodes around 18 or 24 cells. A data acquisition
system has monitored temperatures and current flows during the day,
completing the tests via infrared characterisation during the hours
of maximum irradiance. The influence of the type of module, the number
of cells per bypass diode, the position and amount of shading and
the leakage current of the cell is presented. This information is
useful for cell and module manufacturers and system installers who
must select the necessary protection criteria to guarantee long lifetimes
for PV systems; it also helps to clarify hot-spot testing procedures
in international standards