By combining heat pumps and hybrid panels, the Lisetta Hotel reduces its gas consumption by 75%.

  • 2021
  • Dorf Tirol, Italie
  • Power output : ≤ 36 kWp
  • Panels : 64 hybrid panels
hotel lisetta panneaux solaires dualsun italie

The Hotel Lisetta in Dorf Tirol is environmentally neutral.

Having switched from 100% oil for heating and hot water 12 years ago, the hotel is now a model of successful energy renovation!  

The owners who undertook the work said in an interview with the newspaper Heizungs: “From the beginning, we wanted our carbon footprint to be as small as possible”.

With the technical support of Systent, they were able to identify the best options for reducing the hotel’s CO2 emissions. For example, the intelligent coupling between a latest generation water-to-water heat pump and our DualSun hybrid solar panels provides a very interesting technical solution.

Read more about their technical choices in this article.

A state-of-the-art heating loop

On the heating side, the first action was to replace the old oil burner with a state-of-the-art natural gas boiler.

In addition to this, the integration of air-water heat pumps and the recovery of heat from the refrigeration technology of the cold storage rooms make a further contribution to heating.

But that’s not all.

As Tobias Krechel, former Systent consultant and now hotel owner, explains.

“In order to achieve the highest possible energy efficiency and benefits for the hotel, however, an additional installation was needed, called the ‘eXergie machine’. This is a heat pump that, unlike conventional heating heat pumps, is designed for a higher temperature level and wide temperature range.”

This water-to-water heat pump will serve as a “heat booster” here while increasing the efficiency of the 64 DualSun SPRING hybrid solar panels. In fact, the water-to-water heat pump uses the heat supplied by the DualSun hybrid panels in the low-temperature storage tank.

In addition, both solar heat production and solar electricity production benefit from the cooling of the return circuit to the DualSun SPRING PVT modules:

  • For heat generation, the lower inlet temperature at the collectors allows for better absorption of solar energy.
  • The photovoltaic cells, on the other hand, are rewarded with 0.5% higher efficiency for every degree of cooling.

Solar PV and PVT for self-consumption

On the electricity and hot water side, the installation of 102 m² of photovoltaic and hybrid modules in 2021 will make it possible to supply heat at around 45°C and up to 250 W of electricity per square meter of hybrid module on sunny days.

The solar electricity produced on the roofs is initially consumed by the hotel. Excess electricity is sold and fed into the public grid. If the photovoltaic yield is too low, the electricity is purchased from the grid, but the external purchase of electricity is low. In addition, as it is “green electricity”, the hotel’s power supply is already 100% neutral!

A project that pays for itself in 7 years

Thanks to the eXergie + DualSun coupling, the Lisetta Hotel has been able to reduce its natural gas consumption enormously, which is excellent news from an economic and ecological point of view!

In summer, the production of hot water requires about 75% less natural gas. In the spring and fall, heating the outdoor pool costs about 40% less gas. So in addition to being renewable, it is also profitable!

Thanks to the public subsidies available in Italy and the feed-in tariff for photovoltaic electricity, the investment in the DualSun PVT modules and the water/water heat pump pays for itself after 7 years.

Interview with the owner of the Lisetta Hotel


I am Tobias Krechel, single, 29 years old, until recently a building physics consultant and now a hotel owner. About 80 people live in this hotel, on which 64 Dualsun SPRING panels have been installed on a flat roof. South Tyrol has a lot of sun. The DualSun panels serve a dual purpose for electricity and hot water, including heat dissipation on the flat roof.

How important was it for you to produce your own energy?

Very important for sustainability reasons.

Why did you choose DualSun solar panels?
Easy installation and long experience and existence of the company DualSun. Great homepage with many technical details

How did you hear about DualSun?

Through the installer of photovoltaic modules – Südtirol Solar

How did the installation go?

Quick and easy. Two connectors were not waterproof at the beginning, but this was due to assembly errors.

Are you satisfied with your DualSun installation?

Yes, very satisfied

Would you recommend DualSun to others?

Without a doubt.

Technical information

Characteristics Hotel
Number of panels 64 DualSun SPRING hybrid panels
Power output ≤ 36 kWp
Rooftop installation Flat roof
Thermal system Water-Water heat pump coupling EXernergie
Photovoltaic system Micro-inverters, self-consumption with sale of surplus electricity