The number of circuits necessary for a solar panel installation depends significantly on the solar system's design and energy requirements of the household. Generally, a residential solar array may utilize one primary circuit connected to an inverter. Sizing of the system is crucial; ensuring efficient energy production while meeting the load is paramount, 2. Advanced. Use our solar panel series and parallel calculator to easily find which common wiring configuration maximizes the power output of your solar panels. If VM is not specified then take VM as 80 to 85% of VOC. Step 2: Find the loss of voltage under operating temperature i.