An apparatus which is configured to independently and cooperatively throttle each of a plurality of generators in combinatively supplying electrical power to a load or loads, the apparatus comprising: a plurality of generators, each of the generators having a capacity to produce electrical power, wherein: the generators are interconnected together so as to operate as a single unit, the generators use an energy source to each produce the electrical power, and at least two of the generators use as the energy source a chemical energy source that is a fuel and are each comprised of a chemically heated hot emitter and a photovoltaic cell configured to convert emitted radiation from the chemically heated hot emitter into said electrical power; a power combiner located to deliver the electrical power from the generators to one or more loads; a controller configured to implement an algorithm which independently and cooperatively throttles each of the generators in combinatively supplying the electrical power from the unit to the load or the loads, wherein the at least two generators each comprised of a chemically heated hot emitter and a photovoltaic cell are throttled by limiting the amount of fuel available to them; and at least one sensor, each said sensor arranged to produce an indication of monitored power delivered to the load or the loads, wherein: the load or the loads vary; and the controller is arranged to receive each said indication of the monitored power and is configured such that the algorithm uses each said indication of the monitored power in independently and cooperatively throttling each of the generators in said combinatively supplying the power to match the power to the load or the loads. a plurality of generators, each of the generators having a capacity to produce electrical power, wherein: the generators are interconnected together so as to operate as a single unit, the generators use an energy source to each produce the electrical power, and at least two of the generators use as the energy source a chemical energy source that is a fuel and are each comprised of a chemically heated hot emitter and a photovoltaic cell configured to convert emitted radiation from the chemically heated hot emitter into said electrical power; the generators are interconnected together so as to operate as a single unit, the generators use an energy source to each produce the electrical power, and at least two of the generators use as the energy source a chemical energy source that is a fuel and are each comprised of a chemically heated hot emitter and a photovoltaic cell configured to convert emitted radiation from the chemically heated hot emitter into said electrical power; a power combiner located to deliver the electrical power from the generators to one or more loads; a controller configured to implement an algorithm which independently and cooperatively throttles each of the generators in combinatively supplying the electrical power from the unit to the load or the loads, wherein the at least two generators each comprised of a chemically heated hot emitter and a photovoltaic cell are throttled by limiting the amount of fuel available to them; and at least one sensor, each said sensor arranged to produce an indication of monitored power delivered to the load or the loads, wherein: the load or the loads vary; and the controller is arranged to receive each said indication of the monitored power and is configured such that the algorithm uses each said indication of the monitored power in independently and cooperatively throttling each of the generators in said combinatively supplying the power to match the power to the load or the loads. the load or the loads vary; and the controller is arranged to receive each said indication of the monitored power and is configured such that the algorithm uses each said indication of the monitored power in independently and cooperatively throttling each of the generators in said combinatively supplying the power to match the power to the load or the loads.