SOLAR THERMAL SYSTEM
The basic principle of solar thermal heating is to utilize the sun’s energy and convert it into heat which is then transferred into your home or business heating system in the form of hot water and space heating.
The main source of heat generation is through roof mounted solar panels which are used in conjunction with a boiler, collector or immersion heater. The solar collector will use the sun’s rays to heat a transfer fluid which is usually a mixture of water and glycol (antifreeze) which prevents the water from freezing. The heated water from the collectors is pumped to a heat exchanger which would be inside the water tank in your home. The heat from the exchanger will then heat the water inside the tank. After the liquid releases its heat, the water will flow back to the collectors for reheating. A controller will ensure that the fluid will circulate to the collector when there is sufficient heat available.
SOLAR PHOTOVOLTAICS SYSTEM
When light shines on a photovoltaic (PV) cell – also called a solar cell – that light may be reflected, absorbed, or pass right through the cell. The PV cell is composed of semiconductor material; the “semi” means that it can conduct electricity better than an insulator but not as well as a good conductor like a metal. There are several different semiconductor materials used in PV cells.
When the semiconductor is exposed to light, it absorbs the light’s energy and transfers it to negatively charged particles in the material called electrons. This extra energy allows the electrons to flow through the material as an electrical current. This current is extracted through conductive metal contacts – the grid-like lines on a solar cells – and can then be used to power your home and the rest of the electric grid.
The efficiency of a PV cell is simply the amount of electrical power coming out of the cell compared to the energy from the light shining on it, which indicates how effective the cell is at converting energy from one form to the other. The amount of electricity produced from PV cells depends on the characteristics (such as intensity and wavelengths) of the light available and multiple performance attributes of the cell.
An important property of PV semiconductors is the bandgap, which indicates what wavelengths of light the material can absorb and convert to electrical energy. If the semiconductor’s bandgap matches the wavelengths of light shining on the PV cell, then that cell can efficiently make use of all the available energy.