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Heat pump with solar thermal for more efficiency

(Photo: © MAXSHOT.PL /

Increase efficiency and reduce heating costs by combining a heat pump and solar thermal from Viessmann, and you can achieve both. Then, you will be able to use free solar heat for heating and DHW whenever the sun is shining. If energy-rich radiant heat is not enough, the environmental heating system will step in and make free energy from the earth, the air or the groundwater available for heating. Find out why a system like this is worthwhile and what options there are for combining solar with a heat pump.

A hybrid heating system reduces your power consumption

While heat pumps harness environmental energy with electricity for heating, solar thermal systems operate almost entirely without consumption costs. This is made possible by the free radiant heat from the sun. Collectors convert this into thermal energy before solar medium transports the heat to the cylinder in the house. With the appropriate design, a Viessmann heat pump with solar thermal can be almost completely relieved of its load in summer. For the rest of the year, meanwhile, solar heat ensures greater efficiency. Vitosol 200-FM flat-plate collectors or Vitosol 200-TM vacuum tube collectors convert a large proportion of the incident radiant heat into usable thermal energy.

Combining a heat pump and solar thermal

There are a number of options for combining a heat pump with solar. Solar heat is a widely used method for heating or domestic hot water. In addition, there is also the option to heat the environmental energy source directly.

Use solar heat for domestic hot water or heating

As part of the integration, the solar heat is transferred to the DHW or heating water in a DHW or buffer cylinder. The implementation is comparatively straightforward and can also be achieved with other heat generators, such as gas or pellet heating systems. The following installation options are possible:

  • Domestic hot water heating: Heat from collectors heats the domestic hot water heating in a DHW cylinder. This reduces the demand for heating energy by around five percent. As much as 60 percent of the annual demand for DHW can be covered in this way.
  • Central heating backup: Solar energy heats the heating water in a buffer cylinder, bringing benefits to the central heating system. With large collectors, heating energy consumption is reduced by around 20 percent. For efficient operation, communication between heat pump and solar thermal via the common control system is particularly important. With a Viessmann heat pump and solar thermal, this is guaranteed.  


Heating the environmental energy source with solar heat

Solar thermal can also be used to raise the temperature of the environmental energy source. The combination of brine/water heat pumps, such as the Vitocal 300-G or the Vitocal 200-G, with solar in a Vitoset ice store is particularly efficient. The ice store contains water, which ices up and releases crystallisation energy when heat is extracted by the brine/water heat pump. By comparison, the change from liquid to solid releases the same amount of energy that is needed to heat a litre of water from zero to 80 degrees Celsius. Solar air absorbers passes on solar heat to the environmental heating system, in addition to energy from the air. If this is not needed, it accelerates the regeneration process of the storage unit. In the process, the ice liquefies before the cycle begins again.

Coupling a heat pump with solar thermal and photovoltaics

Would you like to further reduce your energy costs? Then combine the heat pump with solar thermal and photovoltaics. The solar heating system ensures lower power consumption and you can cover this proportionately yourself with the Vitovolt photovoltaic system. You need less power from the public grid and you heat more cost-efficiently. This works even better with a Vitocharge VX3 photovoltaic storage unit, which provides electrical energy even when the sun is no longer shining. We explain what is important, in the article on heat pumps and photovoltaics.


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