Reference project AC•THOR 9s in South Tyrol

South Tyrolean hotel relies on photovoltaic heat

In the Italian Dolomites at the foot of mount Kronplatz, an AC•THOR 9s uses the surplus PV energy for hot water preparation.

Datos sobre el proyecto

Construction type:
Construction year and number of square meters:
PV-power and orientation:
Heat storage size:
my-PV product in use:
System control by/with:
my-PV Referenz Hotel Südtirol

How did you find my-PV?

Residence Montana in South Tyrol is a carbon neutral holiday resort that offers its guests a sustainable vacation in the Italian Dolomites. Delussu Fabiano, the owner of the hotel, discovered my-PV’s YouTube channel while surfing on the internet on the search for environmentally friendly possibilities of heating and hot water generation. The videos of my-PV convinced him of the product quality and supported him in learning more about photovoltaic solutions and how they function.

Obstacles/specialities during the installation

As the responsible electrician had not had prior experience regarding comparable installations, it turned out to be a little bit of a struggle to install the heat sensors. Two digital sensors had to be installed, namely one in the boiler and one in the buffer tank. However, due to the physical distance between the buffer tank and the AC•THOR 9s, an extension was needed to establish a connection. Hereby, the team of my-PV’s support was available during the installation process, which made this special installation possible without any problems.

Brief explanation of the system – what should be mentioned?

Residence Montana is located in the beautiful landscape of the Italian Dolomites. The hotel sets an example for carbon-free business and offers tourists and visitors a carbon-free and therefore sustainable holiday.

Operating costs of the hotel are kept low, as self-generated PV power is independent of price changes from external energy sources, such as electricity from the public grid, gas or pellets etc. In times of less sunshine, such as during the winter season, the hotel is supplied with hydro-based power, which means that there is no reliance on fossil fuels. The only thing in the hotel that is powered exclusively with fossil fuels is the old Vespa, which runs on petrol.

The AC•THOR 9s supplies two tanks with surplus electricity from the photovoltaic system on the hotel roof. The AC•THOR 9s is used here in mode 3 and supplies the boiler (1000 liter) with hot water with 9 kW, as wells as an additional 9 kW (2500 liter) to the buffer tank for space heating during the winter months.

The operating mode M3 enables the continuous regulation of a heating element, depending on the surplus. If there is enough excess PV power available beyond the 9 KW, a second heating element is switched on but is no longer continuously regulated. This offers the advantage of using even more PV surplus for heating purposes in the hotel instead of feeding it into the public grid at a low price.

In addition, a 20 kWh battery storage system is installed in the hotel complex, which is prioritized and charged with solar energy. This means that the heating sector is only supplied when there is surplus PV power.

Electromobility was also considered in the 3-star hotel in South-Tyrol: a total of 7 wallboxes from the company Heidelberg were installed here. This increases the self-consumption of the photovoltaic system enormously, which means that a further expansion of the photovoltaic system is being considered in the future.   

Persons in the household and hot water demand?

During summer as well as during winter the hotel is attracting several visitors due to its location in the scenic landscape at the foot of mount Kronplatz. In addition to hiking and climbing in summer, the location is ideal for winter sports such as skiing and snowshoeing.

During peak times, 60 guests in the hotel have to be supplied consistently with hot water. Depending on the season, the hot water demand is around 120.000 kW/year.

Is hot water backup with mains power used?

No hot water backup is activated for the AC•THOR 9s as the primary heat source is a biomass boiler that covers the whole village, keeping the minimum temperature cost-effective.

On days when there is not enough solar power available, as soon as the temperature in the hot water boiler and in the buffer storage falls below 40 °C, biomass heating is used until a temperature of 60 °C is reached. The temperature for the PV-based heating is set at 75 °C in order to store maximum PV energy in the form of thermal energy.

The AC•THOR 9s offers a high degree of flexibility. At spring-like temperatures from March onwards, no room heating is required and the buffer storage is switched off. The AC•THOR 9s is then switched to mode 1, which means that only 9 kW instead of 18 kW are regulated. No wiring needs to be changed for this. The operating mode can easily be selected in the settings of the AC•THOR 9s.

Any cost changes/ROI?

The return on investment of the AC•THOR 9s would be 3 years. The main idea is to use a maximum of PV as importing power back from external sources is expensive. In light of the low feed-in tariff, increasing the self-consumption of PV energy by using it for space heating and hot water is the most efficient and cost-saving solution.

Opinión personal del cliente y resumen

AC•THOR 9s offers a high level of flexibility regarding the operating mode. From March onwards, there is no demand for space heating. From that moment, operating mode 3 (18 kW) can be changed to mode 1 (9 kW) with just one simple click. AC•THOR 9s simply does the job that it claims. The hotel owner adds that his choice fell on the AC•THOR 9s as it can handle more kw capacity at a better price than comparable products! Also, AC•THOR 9s offers more flexible options regarding heating applications.

my-PV Referenz Hotel Südtirol
my-PV Referenz Hotel Südtirol
my-PV Referenz Hotel Südtirol
my-PV Referenz Hotel Südtirol
my-PV Referenz Hotel Südtirol
my-PV Referenz Hotel Südtirol

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