Free solar energy

Use the free energy from the sun to backup your central heating and heat your domestic hot water, as well as to generate power.

In less than four hours the sun radiates the annual energy demand of the whole world down upon the earth – completely free of charge. Around one third of the total energy demand in the UK is expended on heating buildings. Energy-conscious construction and economical heating systems, such as condensing technology, can substantially reduce this consumption.

This then contributes to the preservation of resources and to the protection of the earth's atmosphere. One important savings potential is offered by DHW heating. In our latitudes, solar collectors combined with a DHW cylinder represent the most interesting alternative to boiler operation, especially during the summer months. In spring and autumn, you may often be able to turn off your boiler when using solar energy to back up your central heating.

Viessmann is a leading European manufacturer of solar thermal systems and can draw on more than 30 years of experience in this sector. This guarantees great returns with a high degree of reliability and quality.


Take advantage of these benefits

  • Solar energy is available free of charge
  • Energy is converted without creating harmful CO2 emissions
  • A solar thermal system offers greater independence from fossil fuels and also saves on heating costs because it can be used for central heating backup and DHW heating
  • With a photovoltaic system, every homeowner can generate their own power – feed-in remuneration and public subsidies make the investment particularly worthwhile

Solar thermal systems: Vacuum tube collectors

Tube collectors

Vitosol 300-T and Vitosol 200-T vacuum tube collectors based on the heat pipe principle represent the highest efficiency and operational reliability. The absorbers with highly selective coating collect a vast amount of solar energy and thereby ensure high efficiency. High grade, corrosion-resistant materials guarantee a long service life.

Solar thermal systems: Flat-plate collectors

Flat-plate collectors

The powerful, long lasting Vitosol 200-F and Vitosol 100-F flat-plate collectors can save on average up to 60 percent of the energy required each year for DHW heating. Meander absorbers and a highly transparent special glass cover ensure extremely high energy efficiency.

Photovoltaic modules

Photovoltaic modules

With Vitovolt 300 and Vitovolt 200, every homeowner can generate their own power. Feed-in remuneration and public subsidies make the investment especially worthwhile. Matching system components allow the efficient utilisation of solar energy for export or consumption on site.

Product info

Efficient on-site consumption of solar power by a heat pump

Increase the on-site consumption rate of solar power through combination with a heat pump

There are currently two ways in which the solar power generated by a photovoltaic system can be used: It can either be exported to the grid, or it can be partially or fully consumed on site. The most efficient way to generate heat from power is by using a heat pump. With a heat pump, one kilowatt-hour of electricity can provide up to four kilowatt-hours of heat by using free natural energy from the environment.

By meeting the energy demand for central heating and DHW heating with the help of a heat pump, users can significantly increase on-site consumption of solar power, whilst also enjoying the lower heating bills it brings. Those intending to combine a photovoltaic system with a heat pump should select a heat pump that specifically optimises on-site consumption and can be adapted to match the generating characteristics of the PV system. For this purpose Viessmann has developed a correspondingly matched system comprised of photovoltaics and heat pump.

Efficient on-site consumption of solar power

Efficient on-site consumption of solar power

On-site consumption offers financial advantages as solar power generated on-site is cheaper than power drawn from the grid. An optimised system concept with perfectly matched components ensures this high level of on-site consumption.

[1] Photovoltaic system
[2] Photovoltaic inverter
[3] Photovoltaic generation meter
[4] Consumers
[5] Heat pump meter
[6] Heat pump with Vitotronic 200 (type WO1C)
[7] Consumption and export/generation meter
[8] Public grid

Optimised system concept with a heat pump

Via an energy meter, the heat pump control unit detects whether the PV system is supplying sufficient amounts of power – which is then used by the heat pump to heat heating water and DHW. The heat yielded this way during the day using photovoltaic gains is held in a well-insulated DHW cylinder and can be used as domestic hot water and for heating as and when required.

With the Vitotronic 200 heat pump control unit from Viessmann, on-site consumption of solar power is automatically increased. Combining the heat pump with a photovoltaic system also offers the option of integrating additional components that increase on-site consumption of generated solar power, such as ventilation equipment, for example.

Before the heat pump is activated, priority is given to meeting the power demand for electrical household appliances using the solar power generated on site. After the demand from household appliances has been satisfied, an energy meter captures the amount of remaining solar power and communicates this to the heat pump. Using the heat pump, the solar surplus can then be stored in the form of thermal energy and made available when it is required. This raises the level of on-site consumption and makes use of the solar energy while it is available.

The economic viability of the photovoltaic system is substantially increased thanks to the deliberate increase in the proportion of on-site consumption. Using low cost solar power also makes the heat pump more economically attractive.