How It All Works!
Solar energy is one of the most abundant and effective types of renewable sources of energy. The best known solar technology is photovoltaic (PV) technology, commonly called as "solar panels". Despite significant progress achieved in recent years in improving this technology and reducing its cost, its efficiency remains relatively low, with the best commercial PV cells achieving ~20-22%. Further progress is associated with significant technological challenges, and there is a theoretical limit of silicon-based PV efficiency which is below 30%. Generating a meaningful amount of electricity with solar PV thus requires a large array which can be impractical.
One of the most efficient solar-based clean energy technologies on the market today is the Solar Thermal System (STC). It is based on the effect of direct absorption of electromagnetic radiation and converting it into thermal energy. It has a much higher efficiency rate than photovoltaic cells. Therefore, to generate the same amount of energy, solar thermal collectors need about ¼ of the area of a solar PV array. This thermal energy is then passed to the end-user and can be used for heating water for domestic or commercial needs, space heating as well as cooling.
STC typically consists of the following main components: solar collectors, circulating pump(s) to transfer thermal energy from the collectors, heat exchanger(s), thermal storage and a controller. The most efficient kind of solar thermal collectors on the market today is evacuated tube collector. The energy collected by the absorber plate with special coating heats the fluid inside the copper pipe and is passed through the dry connection to the heat exchanger. Due to effectively trapping incoming radiation by cutting all three types of thermal loss – radiation, due to the reflective layer inside the vacuum tube, convection, due to the vacuum inside, and conduction due to eliminating contact with outside structure – the efficiency of such collector can exceed 95%.