‘Solar thermal’ systems or solar water heating systems use free heat from the sun to warm-hotwater. A conventional boiler or immersion heater can be used to make the water hotter or to provide hot water when solar energy is unavailable. The benefits of using solar water heating include the following:

  1. It will provide hot water throughout the year. The system works all year round, though you’ll need to heat the water further with a boiler or immersion heater during the winter months.
  2. Your domestic hot water bills will reduce. Sunlight is free, so once you’ve paid for the initial installation your hot water costs will be reduced.
  3. You will have a lower carbon footprint. Solar hot water is a green, renewable heating system and can reduce your carbon dioxide emissions.

Solar thermal systems are comprised of a collection component, working fluid circulation system, a storage component and controls. These components function together to convert solar radiation into heat, which can be used in various applications. Collection component types include:

  • Flat-plate hydronic collectors
  • Flat-plate heat-pipe collectors
  • Evacuated-tube heat-pipe collectors
  • Parabolic-trough collectors
  • Paraboloid-dish collectors
  • Power-tower collector systems

These collectors can be used to produce approximately 50% and more of the hot water needed for residential and commercial use in Europe.

Medium temperature installations can use any of several designs which include pressurized glycol, drain back, batch systems and newer low-pressure freeze tolerant systems using polymer pipes containing water with photovoltaic pumping.

Additionally, European and international standards are being reviewed to accommodate innovations in the design and operation of medium temperature collectors. Operational innovations include “permanently wetted collector” operation. This innovation reduces or even eliminates the occurrence of no-flow high-temperature stresses called stagnation, which would otherwise reduce the life expectancy of collectors.

The applications of a solar thermal system

Solar thermal systems use the sun’s power in terms of its thermal or heat energy for water heating, drying, and evaporation and cooling.

Solar distillation to produce drinkable water

Solar distillation is a solar enhanced distillation process to produce potable water from a saline source. It can be used in areas where, for instance, drinking water is in short supply but brackish water, i.e. containing dissolved salts, is available. In general solar distillation equipmentor stills, is more economically attractive for smaller outputs. Costs increase significantly with increased output, in comparison to other technologies which have considerable economies of scale.

Solar cooling

Several forms of mature technologies are available today for solar thermally assisted air conditioning and cooling applications. In particular for centralized systems providing conditioned air and/or chilled water to buildings, all necessary components are commercially available. The great advantage of this solar application, especially in tropical and equatorial countries, is that the daily cooling load profile follows the solar radiation profile (i.e. office buildings).

Solar cookers (using solar concentrated collected – not water)

Solar cookers can be important because of the increased scarcity of wood fuel and the problems of deforestation in many developing country regions. Solar cookers can also promote cleaner air where there is a problem with indoor cooking.

There are basically two types of solar cooker: oven or stove type. As with conventional cooking stoves, solar stoves apply heat to the bottom of the cooking pot while solar ovens apply a general heat to the enclosed area which contains the cooking pot. However, there are important social issues related to the effective use of solar cookers. There will always be some change of habits required and readiness to change is an important factor that affects the potential impact of this technology.

Maximpact services in the solar thermal area

Maximpact can provide full feasibility and implementation services for the successful implement studies in all renewable energy systems.

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