An irrigation controller is powered for all normal operations by light incident upon an 18 square inch photovoltaic module. Electrical power from the photovoltaic module is stored in high performance "super" capacitors. A transportable battery power source is connected to the controller to power its communication, such as for manual exercise and/or the loading of irrigation control programs. The external battery power source leaves the capacitor power storage recharged at the conclusion of each communication episode. The irrigation controller electronics, save for a real time clock that is updated, are not provided with a timing signal, and thereby consume almost no energy, save for brief millisecond sporadic time intervals of scheduled irrigation control. Capacitor power storage is approximately 6.5 mWH. Worse case photovoltaic energy production is 7.6 mWH daily. The sporadically operative irrigation controller uses less than 6.4 mWH per day, with remaining energy expended on up to 128 ultra-low-power valve actuations per day.
