Interesting facts about solar energy and the sun
The size of the sun is about 1 million times larger than Earth – that is the diameter of the sun is 1,392,000 km compared to the diameter of earth being just 12,756 km – which is about 109 times smaller; for comparison you may consider that the sun can contain upto 1,000,000 earths!
The speed of light travels at about 299,792,458 meters per second – i.e. approximately 300,000 km per second or (1 billion km per hour!)
Light traveling from the sun takes about 8.2 minutes to enter the earth atmosphere covering a distance of approximately 150 million kilometers – or 8.2 light minutes.
Assuming 100% absorption of solar energy, it takes about 88 minutes of solar radiation to cover for overall human energy consumption for a whole year! However, actual absorption of solar radiation is limited to about 1% leaving 99% of solar radiation energy being wasted – see: solar energy potential in solar energy facts.
Solar energy striking the Earth goes about 50% absorbed by Earth itself while 30% of solar energy is being reflected back into space.
The average direct solar radiation (subject to exact location and angle of solar radiance) is estimated at about 1.37 kw per square meter (1370 watts per square meter).
Solar Power facts and solar energy systems – Green house gas equivalents
Solar energy can be used with renewable solar technologies to replace conventional energy systems that consume fossil fuels, thus help reduce harmful emissions into the atmosphere and help reduce greenhouse effect and global warming.
A 10 kw solar panel installation (under certain conditions) is estimated to generate about 17,000 kwh in a year. In environmental terms, this is equivalent to avoiding the emission of 11.7 metric tons of Carbon Dioxide (CO2) into the atmosphere. To help you understand this in real terms consider the following equivalent statements:
Equivalent to the greenhouse gas emissions of approximately 2.3 cars in a year.
Equivalent to CO2 emissions from burning 27.3 barrels of oil
Equivalent to the CO2 emissions from the annual energy use of a house.
Solar energy can be used indirectly as stored thermal energy or directly for generating electricity with solar photovoltaic panels; stored thermal energy can in turn be used for supplying hot water for use, for space heating ( and cooling – solar cooling) or for indirect electricity generation – as in concentrated solar power (CSP).
An example of direct and indirect solar energy system is by comparing solar Photovoltaic panels (PV) and Concentrated Solar Power (CSP) technologies, in CSP vs PV.