Abstract: A power controller system and method for monitoring available power from an input power source, such as one or more photovoltaic (“PV”) cells/panels, and controlling power output to one or more loads. A predetermined threshold input voltage value is assigned to the system. Using the predetermined value, the system determines whether there is enough available power to power the load by measuring only input voltage. In the event the input voltage is greater than the threshold voltage value, then the system delivers power to the load. In the event the load is greater than the available power, the input voltage will drop below the threshold voltage and the system stops delivering power to the load. Power to the loads may be prioritized based on available power so the system turns ON and OFF power to different loads in a particular order.