Global performance measurement of a stand-alone photovoltaic system

The panel efficiency of a stand-alone photovoltaic system is usually used to define the performance of the entire system. The typical efficiency value for silicon modules is about 15%. The performance of all components is a number hard to be known. This paper aims to determine the fully efficiency of the entire PV system, calculating the electrical energy from the frequency inverter output and the total solar energy from the Sun. The relationship between the array and the lead-acid battery dimensioning is shown; the best practices try to reduce the premature capacity loss of the battery, but it also reduces the global performance of the system. An experimental procedure measured the real efficiency of an entire system, that is about 50% of the solar radiation available over the solar modules, which is different from the 84% rate available from the bibliography.