Sun is the ultimate source of energy. This energy from sun is basically intercepted by the earth’s atmosphere in two forms i.e, Heat & Light. Over last few decades various advancement were made by the mankind to absorb these two forms of sun’s energy to satisfy the domestic and industrial energy requirement. The technologies which harvests the light (photon) energy and converts in to electricity is known as Solar Photovoltaic’s and the technology which harvest the heat form of energy and delivers low – high temperature heat energy is called as Solar Thermal Technologies .


The Solar thermal technologies are harnessing solar radiation and delivers heat energy. The technology can able to deliver heat from 60°C - 1000°C in the form of Hot water, steam and hot molten salts. This technology is basically classified in to two categories:

Non-Concentrating Collectors

Non concentrating collectors basically work on the principle of green house effect. It traps the solar radiation falling on its absorber surface and conducts it to the working fluid with the minimal losses. These technologies can able to deliver hot water or hot air at a temperature range of 90 °C - 120°C.

Examples :Flat Plate Collectors, Evacuated Tube Collector, Box Type Solar Cooker.

Concentrating Collectors

Concentrating collectors traps the radiation in its large parabolic reflector surface and focus it in to a small absorber surface which is called receiver. During this process the temperature at receiver can reach as high as 800-1000°C depends on the technology used. These concentrating collectors are able to deliver hot fluid at temperature ranges from 120 °C – 700°C.

Examples :Parabolic Trough Concentrators, Paraboloid Dish, Compound Parabolic Collector.


Solar photovoltaic technology harnesses the solar radiation and generates electricity. The array of solar cells arranged in a manner is called as solar photovoltaic module. The standard photovoltaic modules are available in the capacity of 250Wp/300Wp/330Wp which can be connected in series and parallel to get our desired electrical output. There are several technologies available in Solar PV

Solar Photovoltaic technology contributes a major role in generation of power in renewable energy sector.


Among the domestic and industrial sector approximately 50-60 % of energy consumption is in the form of heat energy. And whenever there is a requirement of such heat energy, solar thermal technologies are most suitable option. These technologies can able to deliver hot-water/steam round the clock with the integration of thermal storage systems completely from sun. Which in return it reduces the dependence and heavy investment of conventional heating sources.

Examples of applications of Solar Thermal Technologies

Domestic Sector: Solar Water Heaters,Solar Cookers, Solar Space Heating Systems, Solar Dryers, etc.,

Industrial Sector: Replacement of fossil fuel fired Boilers, Solar Community Cooking System, Process Heat Delivery, Solar Air-conditions, etc,


For installation of solar thermal technologies the following are the list of pre requisites.

  1. Shadow free land area near to the heat delivery point (Rooftop/ground)
  2. Existing heating arrangement (If any)
  3. Investment

Author : Senthil Kumar

Junior Research Scientist

National Institute of Solar Energy

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