Solar Water Heating

Solar thermal systems are generally composed of panels that convert sunlight to heat. The systems may be used to heat domestic hot water or a swimming pool, or to even make a contribution towards under floor heating. Solar heating panels are one of the most cost effective ways to reduce your utility bills and make a positive contribution towards the environment. In fact the amount of pollution reduced by installing a domestic solar heating system is equivalent to taking one car off the road (i.e. about 1500m³ CO₂ per annum).

There are two types of solar heating collectors; the conventional flat plate collector and the more efficient vacuum tube collectors.

Solar energy - Solar collectors

Sun is ours closest star and directly or indirectly source of almost all available energy on Earth. Sun's energy originates from nuclear fusion in its core, where temperature reaches 15 millions °C. Nuclear fusion is process of joining two light atoms into one heavier atom. Sum of all masses before reaction is larger than sum of all masses after reaction - difference is transformed into energy by famous Einstein's equation E=mc². On Sun, light atoms are hydrogen atoms (input) and resulting atom is helium atom (output). Thanks to nuclear fusion on Sun, every second about 600 million tons of hydrogen is transformed into helium, having 4 million tons of hydrogen transformed into energy as side effect. This energy in form of light and heat spreads itself into the universe with one small part of that energy reaching the Earth. Nuclear fusion on Sun is about five billion years old, which is estimated age of the Sun, and considering available hydrogen stocks it is calculated to last approximately next five billion years. Although Sun's energy makes other energy sources possible, in this chapter we will concentrate strictly on direct use of solar energy. Under optimal conditions, on earth's surface can be gained 1 kW/m², and real value depends upon location, season, day time, weather conditions, etc. On map that shows insolation level is clearly visible that Europe is not located on best place for exploitation, but despite of that direct use of solar energy in constantly increasing in Europe. This is mostly result of some countries politics, which are subsidizing installment of elements which are transforming solar energy in to a usable form of energy. General problems of using this solar energy are small energy flow, huge oscillations of radiation intensity and large investment costs.

Basic principles of solar energy direct use are:

• Solar collectors - preparing hot water and warming the chambers
• Photovoltaic - direct transformation of solar energy to an electricity
• Concentrating solar power - use in large power plants