Evaluation method of generated energy of photovoltaic power system

A problem recently raised is that the generated energy of photovoltaic (PV) power systems installed in the field have obtained about 70/spl sim/80% of the expected energy. This report proposes a method for calculating the system performance ratio excluding loss by cell temperature rise which occupies large proportion in output lowering factors (losses). By applying this method to an actual system, losses such as DC circuit loss, shade-and-stain loss and inverter loss, etc., and the system performance ratio excluding the cell temperature loss could be investigated over a short period without taking into account slight effect of seasons, time zones and radiation fluctuations, etc. As a result of this study, the prospect of individual loss classification and efficiency improvement of PV power systems can be expected.