Design description of the Schuchuli village photovoltaic power system

The engineering design of a stand-alone photovoltaic (PV) power system for the village of Schuchuli (Gunsight), Arizona, on the Papago Indian Reservation is described. The purpose of this experiment was to demonstrate that a stand-alone photovoltaic power system could provide dependable power for basic human needs in a remote village environment. The power system was designed as a limited energy, all 120-V(d.c.) system to which loads cannot be arbitrarily added. The system consists of a 3.5-kW (peak) PV array, 2380 ampere-hours of battery storage, an Electrical Equipment Building, a 120-V(d.c.) electrical distribution network, and equipment and automatic controls to provide control power for pumping water into an existing water system; operating 15 refrigerators, a clothes washing machine, and a sewing machine in the Domestic Services Building; and lights for each of the homes and communal buildings. In addition, a solar hot water heater was provided to supply hot water for the washing machine and communal laundry. The system employs automatic control systems which provide voltage control by limiting the number of PV strings supplying power during system operation and battery charging, and load management for operating high priority loads at the expense of low priority loads as the main batterymore » becomes depleted. The engineering design includes loads profiles and loads descriptions; an explanation of the PV array and battery sizing methodology; descriptions of the mechanical designs; electrical designs and descriptions of the array, battery, controls, instrumentation and distribution system; and a discussion of safety features.« less