The energy system is designed and analyzed using HOMER software. Among the available softwares, HOMER is the most widely used optimization software for hybrid systems  and . This is due to its many possible combination of renewable energy systems and ability to perform optimization and sensitivity analysis which makes it easier and faster to evaluate the many possible system configurations . There are many studies that have used HOMER to examine the technical and economic feasibility of hybrid energy systems worldwide , , , , , , , ,  and . Detailed description of this software can be found in .
The output power of a PV array can be calculated from the following equation and the PV specifications .
where PPV is the rated capacity of the PV array, that is, the power output under standard test conditions in kW; fPV is the PV derating factor [%], GT is the solar radiation incident on the PV array in the current time step [kW/ m2], (GT, STC) is the incident radiation at standard test conditions [1 kW/
m2], ap is the temperature coefficient of power [%/°C], T is the PV cell temperature in the current time step [°C] and T STC is the PV cell temperature under standard test conditions [25 °C]. In a case where the effect of temperature on the PV array performance is neglected, ap can assumed to be zero and Eq. (1) reduces to: