It is not without good reasons that solar energy, or photovoltaic cells are gradually emerging as on of the most viable sources of alternate energy. First of all, with time, it is getting more efficient with costs coming down. The main reason for this is the design improvisations which is making the capture of more concentrated sunlight with reduced cell size. This means that cells can now be manufactured with less cost. And the energy output is more reliable and stronger. Today the cost of solar energy per watt hour has come down to $4 which was unthinkable just 17 years ago, when it was almost double this cost. 

One of the best advantages of solar power is that it does not in any way pollute the environment as it makes use of one of the most abundantly available natural resources available to mankind - sunlight. Even the cells that collect solar energy are getting to be more practical from the users' point of view and they can now be easily installed on rooftops. The system of using solar power is also easy. The home owner can use the power to heat water or light up his home. When photovoltaic cells are used for heating water, the system operates by capturing the water in the cells and then transmitting the heated water through the pipes.  

If you think that photovoltaic cells are incapable of capturing sun rays on a cloudy day, think again. They have successfully overcome this problem and Unisolar, a company specializing in this technology has developed a system of capturing solar rays that function equally efficiently during bad-weather days. They do this by collecting more sunlight from sunny days and storing them for use during cloudy days.