The two types of solar

The Sun is one of the earth’s main life support systems, providing heat and light. Solar energy, which is renewable, is easily available and a clean power source that provides enough energy to meet the world’s annual consumption requirements every 50 minutes. The challenge is to efficiently collect a portion of this heat and radiant energy.

Two major technologies have been developed to harness the sun

Photovoltaic solar technology directly converts sunlight into electricity using panels made of semiconductor cells. Solar thermal technology captures the sun’s heat. This heat is used directly or converted into mechanical energy and in turn, electricity referred to as concentrated solar power. This heat is used directly (low‑temperature solar thermal) or converted into mechanical energy and then electricity (concentrated solar power – CSP). There are two different types of installations that are commonly used: Individual systems for homes or small communities. Photovoltaic panels can power electrical devices, while solar thermal collectors heat homes or hot water.

Photovoltaic or concentrated solar power plants that cover hundreds of acres produce energy on a large scale, which can be transferred into power grids. Solar energy is one of the most appealing renewable energy sources because of its flexibility.  It offers the capacity to power cities and industrial functions utilizing large solar plants while at the same time offering an independent energy generation in the most isolated rural or hard to access regions.

For more on Photovoltaic solar power, see our blog

The photovoltaic effect converts light into electricity. It was discovered by French physicist Edmond Becquerel in 1839 and was first used in industrial applications in 1954. He discovered that an electric current occurs when electrons are displaced. For this to happen, photons (light particles) excite the outermost electrons of the atoms of specific semiconductor elements. In practice, light hitting a photovoltaic cell is converted into electricity by a semiconductor, normally made of silicon. A photovoltaic panel is made up of several cells generating direct current, which is then converted into alternating current by an inverter.

Panels can be used in small systems or large plants

Low-temperature solar thermal power operations produce heat from the Sun’s rays and use it directly. Operating at temperatures below 100°C, the installations serve residential and commercial applications (hot water and heating) as well as to a wide variety of industrial needs. This technology accounts for most of the solar power generated worldwide. Solar thermal collectors are used to collect the heat from the Sun’s rays and transfer it to a heat transfer fluid, such as air, water or antifreeze, which then transports it to the areas to be heated.

Most widespread are flat-plate collectors, which are made up of a dark surface area that absorbs the Sun’s rays and a layer of thermal insulation topped with a sheet of glass that generates a greenhouse effect. Collectors operate at up to 70°C above ambient temperature. There are also solar thermal air collectors, used for agricultural crop drying, for example, and unglazed systems made using rubber or plastic, rather than a glass covering, which are used primarily to heat swimming pools. Vacuum tube collectors are best suited to high-temperature industrial uses, such as cleaning slaughterhouses or pasteurizing canned goods. They are made up of glass vacuum tubes for optimal thermal insulation. Inside, an absorber captures the solar energy and transfers it to a fluid.

Concentrated solar power

This type of thermal solar power technology concentrates the warmth of the Sun’s rays using collectors to heat a transfer fluid (gas, oil or molten salt,  to a high temperature. The fluid heats a network of water, which produces steam and drives a turbine (mechanical energy), thereby generating electricity. Heat from the sun’s rays is collected in large power plants where flat or curved mirrors are created over vast areas. The technology is best suited to countries where the sunlight is intense, for example in desert regions.

Choose the solar method that works best for you!

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