Types of Solar energy can be classified into two categories depending upon the mode of conversion and the type of energy it is converted into. Passive solar energy and active solar energy belong to the mode of conversion and solar thermal energy, photovoltaic solar power, and concentrating solar power.
- Passive solar energy refers to trapping the sun’s energy without using mechanical devices.
- Active solar energy uses mechanical devices to collect, store, and distribute energy.
- Solar thermal energy, this energy is obtained by converting solar energy into heat.
- Photovoltaic solar power is the energy obtained by converting solar energy into electricity.
- Concentrating solar power, This is a type of thermal energy used to generate solar power electricity.
Types of Solar Energy Included:
Solar Photovoltaic Plants
Solar photovoltaic systems are the most common type of solar energy system that produces electricity directly from sunlight. Also known as solar cell systems, it uses semiconductor materials for absorbing sunlight. It works in a way that the heat from the sun’s radiation makes the electrons lose their atoms. These electrons then flow through the semiconductor materials and produce energy.
Thanks to technological advances, today’s solar photovoltaic plants can absorb and convert most of the visible light spectrum and most of the infrared and UV light spectrum into energy.
Some of the well-known examples of the use of solar photovoltaic cells are solar-powered clocks and calculators. Several photovoltaic cells are required to provide sufficient power to households. However, for large-scale industrial applications, hundreds of photovoltaic arrays would be needed to form a large photovoltaic system.
Photons strike and ionize semiconductor material on the solar panel, causing outer electrons to break free of their atomic bonds. Due to the semiconductor structure, the electrons are forced in one direction creating a flow of electrical current. Solar cells are not 100% efficient in crystalline silicon solar cells, in part because only certain light within the spectrum can be absorbed.
Solar Water Heating Systems
As the name suggests, solar water heating systems use the sun’s energy to heat water or bring it to a boil. In nature, shallow parts of the lakes, ponds, and rivers have warmer water than deeper areas. The sunlight can easily reach the bottom of the shallow areas, causing it to heat it, making the water warm. The same concept has been used to develop solar water heating systems.
Essentially, the design incorporates two primary segments – a water storage tank and a solar collector. The ones installed in homes and residential buildings are flat-plate collectors that are installed on the roofs facing the sun.
The collector and the storage tank are connected via small tubes that carry water. As the flat-plate collector absorbs the sun’s heat, it heats the water passing through the tubes.
If the sun’s rays are concentrated by mirrors, much higher temperatures can be created. The light is focused onto a central point with a carrier fluid such as oil flowing through it. The oil heats up to around 400C, hot enough to heat water and make high-pressure steam that can drive a turbine and generate electricity.
Solar concentrators only work in direct sunshine. The mirror is held on a support that can turn to follow the sun as it moves throughout the day, adding to complexity and cost. The two commercialized CSP technologies are Power Towers and Parabolic Troughs. Other CSP technologies include Compact Linear Fresnel Reflector (CLFR) and Dish Engine. CSP specific conditions to produce power, such as areas where direct sunlight is most intense and contiguous parcels of dry, flat land.
A solar thermal panel is simply a black surface that absorbs light, heats up, and transfers the heat into a working fluid. It can be unglazed or glazed. Glazed panels can be flat, or made up of a collection of glass tubes. The working fluid moves the heat to a place where it is useful – perhaps a hot water store, swimming pool, or directly to space heating for a building.
Panels with higher levels of insulation, such as a glazed cover above and thermal insulation behind do not require direct sunshine to operate and will collect heat on a cloudy day.