This chapter is focused on solar cogeneration systems. These systems are silicon unijunctioned photocells with an optimal combination of the value of solar radiation concentration ratio and solar cell cooling intensity within the laminar flow of the coolant. This is based on the balance of the power which is released by the photocells, into the electrical and thermal network and dispersed into the environment. There is an engineering method for calculating the annual productivity of linear photovoltaic panels presented. The principles of designing solar radiation concentrators and photovoltaic panels is also considered. A fundamental new technique for testing linear photovoltaic panels with a sun concentration is proposed. This is when the absolute temperature of the radiating surface is logically introduced and a difficultly determined parameter is excluded, taking into account the temperature distribution along the surface of the absorber, from the location of the coolant.