Solar Thermal Technologies

Overview

Solar thermal technologies involve harnessing solar energy for thermal energy (heat).

Solar thermal technologies comprise flat or parabollic collectors (low and medium temperatures and high temperature collectors) concentrating sunlight mainly using mirrors and lenses.

Solar Thermal Heating

Solar heating is the utilisation of solar energy to provide process heat, especially in crop drying, water heating, cooking or space heating and cooling. Advanced designs are also used to generate electricity.

Solar Water Heaters (SWH)

• See Main Article: Solar Water Heaters

Solar collectors are applicable worldwide and are even suitable in areas with low solar radiation and short periods of sunshine. The technology of solar thermal water heaters is present worldwide and significant deployments occur already in emerging economies and developing countries.

Concentrating Solar Thermal Power

Concentrating solar thermal powersystems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. The concentrated heat is then used as a heat source for a conventional power plant. A wide range of concentrating technologies exists; the most developed are the parabolic trough, the concentrating linear fresnel reflector, the Stirling dish and the solar power tower. Various techniques are used to track the Sun and focus light. In all of these systems a working fluid is heated by the concentrated sunlight, and is then used for power generation or energy storage.

Solar energy can also be concentrated and used for cooking applications. This is done using a wide range of technologies such as box cookers, solar bowls and the Scheffler reflector.

Solar Cooking

• Main article: Cooking with the Sun

Solar cooking allows cooks to heat, cook, bake or pasteurize food or drink. Solar Energy can be an ideal component of the energy mix of a household to complement other combustion-based stoves that can produce heat on demand based on other fuels if the sun does not shine. Local dishes. cooking habits and local climatic conditions determine how much alternative fuels can be saved, around 30%-40%.

Solar Thermal Cooling

• See Main article on Solar Cooling

Solar thermal energy power stations may also be used for cooling: this refers to either cooling buildings (air conditioning) or industrial processes (refrigeration). Through evaporation and condensation, the solar thermal energy is processed as cold.

There are open and closed systems. Most widely used are closed systems like absorption refrigeration machines and open cooling and dehumidifying processes, such as sorption-supported air conditioning.

The market is at a very early stage, with around 1-2,000 cooling systems have been installed up until 2014. The interest in solar cooling products continues to increase. They are more attractive, in case of high electricity prices and frequent electricity outages. Today, numerous systems from various manufacturers are offered on the market and have reached considerable technical maturity.

Further Information

• Solar portal on energypedia
  
• Solar Thermal Applications in Industries in India
  
• Solar Water Heaters Worldwide - Market Development
• Solar Water Heaters – Project Examples
• http://en.wikipedia.org/wiki/Solar_thermal_energy
• http://www.therenewableenergycentre.co.uk/solar-heating
• http://www.isfh.de/institut_solarforschung/solarthermie.php
• http://en.wikipedia.org/wiki/Solar_thermal_collector
• practicalaction.org/solar-thermal-energy-1
• International Energy Agency. ‘Renewable Energy Essentials: Solar Heating and Cooling’, 2009. https://www.iea.org/publications/freepublications/publication/Solar_heating_cooling.pdf 
• http://www.undp.org/content/undp/en/home/ourwork/ourstories/india-brings-sun-into-the-kitchen.html