A comparison of photovoltaic module performance evaluation methodologies for energy ratings

The rating of photovoltaic (PV) modules has always been a controversial topic in the PV community. There is no industry standard methodology to evaluate PV modules for energy production. This issue must be discussed and resolved for the benefit of system planners, utilities, and other consumers. Several methodologies are available to rate a module's peak power, but do any accurately predict energy output for flat-plate modules? This paper analyzes the energy performance of PV modules using six different energy calculation techniques and compares the results to the measured amount of energy produced. The results indicate which methods are the most effective for predicting energy output in Golden, Colorado, under prevailing meteorological conditions.