A method for converting heat energy to electric power using sub-micron gap thermo photovoltaic technology, comprising the steps of: collecting heat energy by a collecting surface of a radiation-emitting layer from an inner surface of a thermally-conductive shell, an outer surface of the thermally-conductive shell being exposed to a heat energy source; maintaining a receiving surface of a photovoltaic cell by spacers in a micro gap less than one micron distance from an emitting surface of the radiation-emitting layer; receiving electromagnetic radiation by the receiving surface from the emitting surface; providing pressure on the photovoltaic cell by a thermally conductive, deformable foil membrane positioned between the photovoltaic cell and a pressurized chamber containing liquid metal for keeping the collecting surface of the radiation-emitting layer in close contact with the inner surface of the thermally-conductive shell and for maximizing cooling of the photovoltaic cell; characterised by: providing pressure by a pneumatic chamber maintained at a controlled pressure on a coolant chamber, a heat sink in between the coolant chamber and the chamber containing liquid metal, the heat sink in contact with the pressurized chamber containing liquid metal, the photovoltaic cell, the radiation-emitting layer, and the thermally-conductive shell for further maximizing cooling of the photovoltaic cell; and circulating coolant liquid through cavities in the heat sink and the coolant chamber through use of flexible bellows and a coolant liquid distribution housing. collecting heat energy by a collecting surface of a radiation-emitting layer from an inner surface of a thermally-conductive shell, an outer surface of the thermally-conductive shell being exposed to a heat energy source; maintaining a receiving surface of a photovoltaic cell by spacers in a micro gap less than one micron distance from an emitting surface of the radiation-emitting layer; receiving electromagnetic radiation by the receiving surface from the emitting surface; providing pressure on the photovoltaic cell by a thermally conductive, deformable foil membrane positioned between the photovoltaic cell and a pressurized chamber containing liquid metal for keeping the collecting surface of the radiation-emitting layer in close contact with the inner surface of the thermally-conductive shell and for maximizing cooling of the photovoltaic cell; characterised by: providing pressure by a pneumatic chamber maintained at a controlled pressure on a coolant chamber, a heat sink in between the coolant chamber and the chamber containing liquid metal, the heat sink in contact with the pressurized chamber containing liquid metal, the photovoltaic cell, the radiation-emitting layer, and the thermally-conductive shell for further maximizing cooling of the photovoltaic cell; and circulating coolant liquid through cavities in the heat sink and the coolant chamber through use of flexible bellows and a coolant liquid distribution housing. providing pressure by a pneumatic chamber maintained at a controlled pressure on a coolant chamber, a heat sink in between the coolant chamber and the chamber containing liquid metal, the heat sink in contact with the pressurized chamber containing liquid metal, the photovoltaic cell, the radiation-emitting layer, and the thermally-conductive shell for further maximizing cooling of the photovoltaic cell; and circulating coolant liquid through cavities in the heat sink and the coolant chamber through use of flexible bellows and a coolant liquid distribution housing.