2. Thermodynamic solar

The potential of solar energy is enormous [D 3 900] , ref. [1] and the differences in energy received annually, between the sunniest and least sunny areas, only vary by a ratio of 1 to 2. But solar irradiation fluctuates (day-night alternations, seasonal rhythms, clouds), requires storage at isolated sites and can be "solar-powered" when connected to the grid.

The maximum power radiated at ground level is around 1 kW/m ² , and can reach 1.2 kW/m ² in certain cloudy reflection situations. A 100 m square in the south of France receives 14 · 10 ⁶ kWh of heat per year, or 1,400 kWh/m ² per year, with power...