As a source of energy, nothing can be compared with the sun. Solar energy is so called renewable source of energy which means it has very vital and promising role on our whole civilization. Nowadays humans have to be very efficient and capable to use all these sources of renewable energy to harness our economical and social growth.
At the moment, sun’s contribution to human energy needs is crucial. But, total solar energy market remains quite small. It covers below 1 % of total energy consumption, compared with roughly 85 % from oil, natural gas, and coal.
Those fossil fuels cannot remain the dominant sources of energy forever. For a long-term, sustainable energy source such as solar power offers an attractive alternative. Its availability far exceeds any conceivable future energy requirements. It is environmentally clean, and its energy transfer from the sun to the Earth is free of charge.
Many of the technologies to resolve these issues already exist. Dishes can concentrate the sun’s rays to heat fluids that drive engines and produce power which is a possible approach to solar electricity generation. Another popular method is direct production of electric current from captured sunlight.
The efficiency of solar energy technology
Energy consumption has been growing worldwide during the last decade. It is well known that growing population usually accelerates energy consumption. Nowadays, fossil fuels supply a huge percentage of the primary energy consumed worldwide. This fact is responsible for the global warming and climate change. On the other hand, energy is a key asset in the welfare of humankind and its development. It is also important to understand the definition of energy efficiency. In general, it is the need for rationalization and reduction of energy consumption and to which a set of actions contribute to improve its use.
Let’s return to solar energy issue. Today’s commercial solar cells normally convert sunlight into electricity with an efficiency of only 10 % to 20 %. To make solar economically competitive, engineers must find ways to improve the efficiency of the cells and to lower their manufacturing costs.
Basically, prospects for improving solar efficiency are promising. Current standard cells have a theoretical maximum efficiency of 31 % due to the electronic properties of the silicon material. But, new materials can evade that limit. Experimental cells have exceeded 40 % efficiency.
Can solar energy be more economical?
A key issue here is material purity. Current solar cell designs require high-purity, because impurities block the flow of electric charge. That problem would be avoided if charges had to travel only a short distance, through a thin layer of material.
Another interesting thing here is an application of renewable energy in building systems. Because of its energy-efficient technology and friendly environmental benefits, building combined cooling heating and power (BCHP) system is broadly identified as an alternative for the world to meet and solve energy-related problems and environmental issues. Solar energy has been applied to BCHP systems for its compromising environmental benefits and cost saving potentials.
Clean solar energy
The solar power satellites concept has been around late 1968. The method of transmitting power to the earth using microwaves from the small antenna on the satellite to a much larger area on the ground is known as rectenna. The concept has again become interesting due to increased energy demand and cost.
The space has several advantages over Earth for the collection of solar power. There is no air in the space, so satellites would receive somewhat more intense light unaffected by weather and day night cycle. This received amount of energy will be transformed in microwave energy and will be transmitted through the antenna previously place on satellite aimed at Earth.
The solar power satellite essentially consists of 3 parts: (1) a micro wave antenna on satellite aimed at earth, (2) a huge solar collector made up of solar cells, (3) an antenna occupying large are on the earth to collect the power disadvantages for lower orbits. Satellite power and obvious choice would be to look for an orbit which maximises the use of the power system on the night side on the Earth.
The storage of solar energy
Many technologies offer mass-storage opportunities. New materials could greatly improve the effectiveness of capacitors, superconducting magnets, or flyweels, all of which could provide convenient power storage in many applications.
Another possible solution to the storage problem would mimic the biological capture of sunshine by photosynthesis in plants. The plant’s way of using sunlight to produce food could be duplicated by people to produce fuel. Fuel cells have other advantages. They could be distributed widely, avoiding the vulnerabilities of centralized power generation.
One of the greatest engineering challenges nowadays is to improve solar cells, reduce their costs, and provide efficient ways to use their electricity to create storable fuel. If we resolve all this problems in the future a solar power will assert its superiority to fossil fuels as a sustainable motive force for civilization’s brilliant prosperity.
 Aditya goel, Rishi P Jamdagni, N. K.Mishra, New Hope for Clean Energy through Exploring Space, IEEE, 2010.
 Dr. D. Biran, Prof. A. Braunstein, Solar Electrical Systems for Communication, IEEE, 1978.
 J. Galvão, S. Leitão, S. Malheiro, T. Gaio, Model of Decentralized Energy on Improving the Efficiency in Building Services, IEEE, 2010.
 Jiang-Jiang Wang, He Bai, You-Yin Jing, You-Yin Jing, Economic Analysis and Optimization Design of a Solar Combined Cooling Heating and Power System in Different Operation Strategies, IEEE, 2011.