I was going to entitle this article “solar heating for the home” but since heating is not the main use for solar energy in the home I renamed it. Common sense tells us why solar energy is not immensely useful for residential heating. When we most need it, in winter the sun is less effective and there are fewer daylight hours.
The Technology behind Solar Energy
A number of technologies have been developed to make use of solar radiation. Some of these make direct use of solar energy for lighting and heating etc., while others produce electricity. They are:
1. Solar thermal energy collection systems generate electricity through mirrors and a system of tubes filled with fluid.
2. Solar thermal collectors which are used to make heat.
3. Photovoltaic panels make D.C. current electricity from sunlight. For home use though, the electricity generated has to be converted to A.C. which makes it prohibitive. However, in a sunny country, you can produce enough power to run a 100W light bulb from a single square metre of solar panel.
4. Solar hot water panels which heat water in the home.
How Efficient are Solar Panels?
Solar panels produce very little power in shady or cloudy conditions so are most efficient in direct sunshine. Surprisingly, solar panels used in very hot climates are less efficient than those used in sunny but cold countries because it is light that makes electricity not heat.
At different times during the day, as the sun’s angle to the panel differs, the amount of energy produced varies. Most often it is better when the panel is sloped but on cloudy days horizontal mounted panels are more productive. The most energy is generated when the panel is pointed directly towards the sun.
Although the popularity of home solar energy has been decreasing since the 1970s, billions of dollars have been spent on developing Photovoltaic systems in America and Japan. Lately, Germany has also joined in the research so costs are falling. Also, in some countries you can recoup some of your expenses by selling excess energy back to the electricity companies.