Solar radiation warms our oceans, creates our climate and grows our food. The sun delivers more solar energy to the earth in one hour than the entire world uses in one year. Modern technology is making it easier and more efficient to harness this unlimited source of heat. But how well does solar heating work?
Solar heating is not the same as solar power. Both harness the heat and light from the sun, but solar power is the electricity that is generated from:
Solar heating simply takes the heat energy of the sun and transfers it to somewhere more useful, like your living room or throughout an entire building.
We all know that a room in full sunlight gets hot. For centuries, humans have taken advantage of this free heat by constructing buildings to gather (or shield) the sun's rays. A well-thought-out design of a building and its surroundings can maximize the benefits to our indoor environments. For instance, in northern latitudes, solar heating works well when windows are placed on south-facing walls. Radiant heat is absorbed by objects in the room which then warms the indoor air.
Building materials can also be used to heat an indoor environment. In hot climate zones, homes are built with concrete walls. During the day, the rock absorbs solar energy and keeps the inside dwelling cool. At night, the warmed surface radiates the stored heat and releases into the home. It's a simple and elegant heating cycle that's virtually maintenance free.
Solar heating can efficiently supplement other primary residential heating systems. Large, dark surfaces will warm the surrounding air which can then be distributed throughout a building. Proper ventilation, such as a simple fan, will draw cooler air over the solar collector thus, keeping the cycle going. As long as the sun is shining, free heat can be drawn from the solar collector.
Approximately 174 PW of solar radiation enters the earth's atmosphere every year (1 PW = 1012 kW) and here's where it goes.