What is solar energy
Solar energy is radiant light and heat. The earth receives 174 petawatts (PW) from the sun in the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, sea and ground. The sun's light at the Earth's surface is mainly distributed in the visible and near-infrared energy with a small part in the near ultrafiolett.
The sun transfer 17,000 times more energy to earth than that man needs.
The solar intensity through the atmosphere is approx. 1400 Watt / m2 and the heat at the Earth's surface depends on the location (north / south), but first and foremost the number of solar hours.
Our technology makes it possible to utilize about 80% of solar energy.
Solar thermal energy can, in other words, be utilized in all locations of the world and the number of solar hours determines how much energy yield you can expect.
At left you'll see a comparison between the most used energy sources in the world.
At bottom right of the figure, you'll see a gray cube that represents the world's man created energy needs through a year.
For comparison:
1) the world's oil reserves - about. 50 years
2) the world's gas reserves - about. 65 years
3) the world's coal reserves - approximately. 250 years
4) the world's nuclear power reserves - ca. 60 years
The yellow cube represents the energy contribution from the sun during a year.
The major challenges in relation to the utilization of solar energy is related to the storage of energy over time. Within this field imense research has started.
IEA (International Energy Agency) has prepared forecasts which indicate that all new housing in the western world will be 100% driven with solar energi by 2030.
Facts about solar energy
The reason for using the sun as energy source is that the Earth's surface receives about 1400 W / m2, measured on a surface that is normal to (in a right angle) the sun. About 19% of the energy is absorbed in the atmosphere, and clouds reflect in average 35%. Generally, you calculate 1020 W per square meter at sea level, but this varies with the location in relation to latitude, and not least the number of solar hours in the form of clear weather without clouds.
Solar thermal energy can, in other words, be utilized in all locations of the world and the number of solar hours determines how much energy yield you can expect.
Below are some links to information about solar energy: