The energy obtained from the sun is known as solar energy. This energy can easily be harvested and converted to use to attend to the challenges of the short supply of energy in our various homes and offices.
A solar-powered (photovoltaic) (Pv) panel is used to convert electricity by exciting electrons in silicon cells using the photons of light from the sun. The electricity obtained can be used to supply renewable energy to various homes and offices.
Production of Solar Energy:
A huge amount of heat energy is produced by the sun during fusion at a very high temperature due to the combination of two hydrogen isotopes to produce a helium atom. It looks like this in a very simplified way:
H + H → He + Energy
Through this process, a large amount of heat is released into space which is about 4 x 1026 joules per second. Energy can easily be trapped using solar collectors to generate electricity for home consumption.
A solar collector is a device that collects and concentrates solar radiation from the sun. They are primarily used for active solar heating and allow heating of water for personal use.
Types of Solar Collectors:
1. Flat Plate Collectors:
These are simply metal boxes that have some sort of transparent glazing as a cover on top. They are usually mounted on a rooftop or a high stand. They are designed to operate at low temperatures of about 65°C to surrounding temperatures of about 100°C.
It consists of:
1. A metal flat plate that receives solar radiation and blackened absorber plates, usually made of a good conductor of heat e.g. copper or aluminium.
2. Tubes attached to the absorber plates which assist to circulate liquid (e.g. water) that remove thermal energy from the plates.
3. Heat insulator provided at the back of the absorber plates to minimize heat losses
4. A transparent cover (glazing) which is made of glass to:
- Reduce heat loss in the upward direction.
- Permit maximum energy transmission of the solar energy to the metal plate.
- Prevent the absorber plate from direct exposure to weathering.
All the components are enclosed in a metal box, with a dark-coloured absorber plate at the back.
2. Focusing Plate Collector:
Point focus collectors are large parabolic dishes composed of some reflective material that focus the sun’s energy onto a single point. The high-intensity radiation is focused on the black absorbing surface receiver which is insulated to minimize heat losses.