Abstract: A hybrid power system has two voltage sources, a variable DC power source, and a second power source, connected through selection components to a common node. The variable DC power source may be a solar power source and the second source may be an AC grid. The selection components, e.g. blocking diodes, SCRs, or relays, allow one or both of the sources to be connected to the node depending on the voltages produced by the sources. A variable speed drive and load may be connected to the node.

Abstract: In a readily switchable multiple solar panel system, the individual solar panels are interconnected with a control or switching apparatus which allows the solar panels to be readily switched into various series, parallel, or series-parallel configurations. With a relay based switching apparatus, a relay is connected between a pair of solar panels, so that in a first state, the panels are in series where the total voltage is the sum of each individual panel's voltage. When the relay is switched to the second state, each solar panel is in parallel, where the total voltage is a single panel's voltage and the current is multiplied by the number of panels. Multiple panels can be connected in this manner, with a relay between each successive pair of panels. With each relay connected in a parallel arrangement, a simple control switch in series with the relay coils can control the panel switching. The coil of each relay can also be individually controlled.

Abstract: It is difficult to control a variable speed converter or inverter so that an AC motor or other load may be operated from a DC source under varying source and/or load conditions. A DC bias voltage control related to AC frequency by a predetermined relationship is used to control the DC to AC converter. For variable speed AC converters, a low voltage bias control circuit is effectively used to control motor frequency by applying a bias voltage to the converter so that the load requirements are optimally met by the available DC source voltage. The controller can be used in many DC source—bias controlled converter—AC load systems formed with the bias controlled drive, for example a solar powered water pump in which a DC photovoltaic panel is used to power an AC pump motor.