Research on Evaluation Methods of Generated Energy and Lowering Factors of Photovoltaic Generation System

There has been a lot of productive research done in the field of photovoltaic (PV) power generation, but there are still some problems including the energy generated by PV systems is fairly small in comparison to the expected energy, and the output dispersion of individual systems is also large. In order to evaluate whether the expected energy can be obtained, the evaluation of generated energy has been carried out using coefficients such as “the performance ratio" which divides the actual generated energy produced for one year by the calculated output energy of the PV array for an equal period. However, there are some limitations, such as that long-term continued measurement of data is necessary, it is hard to investigate factors which lower the generated energy and improve the system efficiency, etc. The authors have carried out research in accurately evaluating generated energy. A method for classifying loss due to solar temperature rise has also been researched and clarified by the measurement of data over a short time period. Further, the loss on the MPPT operation (P_max operation) could similarly be classified and analyzed.