Sustainable Energy and Smart Grids: Breakthrough in Thinking, Modelling, and Technology

Solar power is the production of electrical energy from solar radiation. The best-known form of solar energy is probably photovoltaics, the direct conversion of solar energy into electricity using solar cells. A less well-known and less used form of solar energy is concentrated solar power, where solar energy is concentrated to heat steam and drive a steam turbine. Solar energy is also used directly for heating. During the past decade, the growth of solar energy has been in the order of 50 per cent per year, which is larger than the growth of wind energy.

The potential for growth is enormous: the amount of solar energy reaching the earth is four times larger than the planet's total energy consumption. The production of solar energy varies with the day and night cycle and depends on the weather. The global formula to estimate the electricity generated by a solar panel is $E=A*r*H*PR$, where $E$ is the generated energy (kWh), $A$ the total solar panel area ($m^2)$, r the solar panel yield (%), $H$ is the annual average solar radiation on tilted panels, and $PR$ is the performance ratio, where the coefficient for losses ranges between 0.5 and 0.9. This formula shows that the amount of energy produced by solar panels depends heavily on the sunshine at the location of the panels: the panels have the highest energy production in countries around the equator (see figure 5). Unlike large-scale hydroelectricity and wind energy, an important part of solar energy is produced with small-scale solar panels connected to the local distribution grid throughout the power system.

Figure 5. The three-year average of solar irradiance, including nights and cloud Coverage. Sunlight hitting the dark discs could power the whole world: if installed In areas marked by the six discs in the map, solar cells with a conversion efficiency of Only 8 per cent would produce, on average, 18 TW electrical power. That is more than The total power currently available from all our primary energy sources, including Coal, oil, gas, nuclear, and hydro.