The sun is a massive energy source. It emits energy of 3.8¡Á1020MW per second in the form of ray radiation to the outer space. One in a 2.2 billion of the energy is projected to the earth, and the energy the earth receives from the sun is in a year can be up to 1.8¡Á1018KWH, which is an extremely huge energy irreplaceable with any other form of energy. Solar cell is a semiconductor device that directly converts solar energy into electric energy. By combining large numbers of solar modules (mainly silicon solar modules), a PV power station can be established, which can provide reliable energy to industry agriculture, communication and human life s a convenient power station. From 1970s to the beginning of 1990s, PV power stations were mainly used to provide household electricity for residents in areas short of electricity or without electricity and also to provide maintenance-free power sources for communication, microwave relay station, petroleum pipeline and gas delivery pipeline cathodic protection, maritime navigation marking lights, etc., which achieved great success. Since 1990s, cost of PV power station has dropped substantially, and more importantly, unending usage of conventional energies causes serious pollution to the environment the mankind lives on, therefore utilization of solar energy in a massive scale has been an effective way of preventing pollution and improving the existence environment of the mankind himself.

 Developed countries like America, Japan, Germany, the Netherlands and Australia all increase investment in PV power technology and production in succession, thus expanding the scale and field of its application. One measure is to build large-capacity PV power stations, for example, America has built a PV power station with a capacity of 7MW,supplying power for a small city. Another measure is to quickly apply the PV power system in buildings, for example, install the system on the roof to provide urban residents with electricity for living, combine photovoltaic modules and the buildings to replace the present glass walls when constructing public buildings, like airports, hotels, etc., and establish the so-called solar energy buildings.

 This kind of solar energy building has multiple functions. In the daytime, it not only can generate power and store the power in batteries or be combined to the electric grid, but also can let some sunshine permeate, providing lighting and heat source for the room. In the evening, energy inside the batteries or electric power of the electric grid can be used to provide electricity for lighting and warming, etc. In the long run, it plays an important role in greatly reducing the shortage of electricity at peak time in large cities. In the meantime, since solar modules can be designed and manufactured according to requirements of buildings and conform to the style of modern architecture, they are more beautiful and scientific than the currently extensively used curtain-wall glass, and become a new eye-catching landscape in modern metropolises.