The energy falling on the surface of the earth from the sun is actually much greater than the amount of energy we use, or can use. Solar energy is reasonably predictable, and is not associated with any environmental risk.
There are two main ways that solar energy is used in our buildings :
1. Solar Heat 2. Solar Electricity
It is worth noting that Solar light (light from the sun), which we take most for granted can also be exploited in building design to even further minimise the need for artificial lighting during daylight hours.