Most renewable energy comes either directly or indirectly from the sun. Solar radiation reaches the Earth's upper atmosphere at a rate of 1,366 watts per square meter (W/m²). However, not all of this energy is available for use at ground level. While traveling through the atmosphere, 6% of the incoming solar radiation is reflected and 16% is absorbed resulting in a peak irradiance at the equator of 1,020 W/m². Average atmospheric conditions (clouds, dust, pollution) further reduce insolation by 20% through reflection and 3% through absorption.

This sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses.

Solar energy can be applied in many ways, including to:

-  generate electricity using photovoltaic solar cells

-  generate electricity by heating trapped air which rotates turbines.

-  heat buildings, directly and using solar walls.

-  Heat/cook food, through solar ovens.

-  heat water for domestic consumption and heating using rooftop solar

   panels.