Full power with AC•THOR 9s
Photovoltaic heat in a 400-year-old farmhouse
A newly renovated agricultural building is used as a weekend house and is powered by the sun.
Facts about the project
- Owner/planner
- PV power and orientation
- Type of building
- Year of construction and construction size
- Heat storage size
- my-PV product in use:
- System control by:
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12 years of renovation for a farmhouse
The 400-year-old agricultural building, which was renovated in 2023, was previously heated solely with a 35 kW Fröling P1 pellet heating system. In order to relieve the primary heating system in the future, the innovative owner of the home started looking for a practical addition. Due to its agricultural use, his property offers a large roof area that has been equipped with a photovoltaic system. 30 kWp is distributed over the cardinal points east, south and west; installed in the angle of the roof structure.
The only drawback to the renovated old building: the quarry stone walls of the old farm are anything but well insulated, even after the renovation. Therefore, a lot of energy is required for heating. The owner was looking for a solution to solve this issue.
How was the path to my-PV solutions?
With the large photovoltaic system, the renovated building, which was mostly used as a weekend house or holiday home, yields a high level of surplus energy, which was fed into the public grid. The situation changed in summer 2023, when Mr. Malinowski became aware of self-consumption optimization via the Internet. With the aim to use more of the photovoltaic electricity available directly in the household, a simple and cost-effective retrofit had to be made. With the use of a photovoltaic power manager from my-PV, namely the AC•THOR 9s, it is very easy to increase the degree of self-use – continuously and depending on the photovoltaic surplus.
With the help of the videos of the my-PV YouTube channel, the owner developed an understanding on how the device works. After a little research on the my-PV website, the decision clearly went in favour of the photovoltaic heat solution from my-PV. A little research on the website and the decision was made that an AC•THOR 9s would be purchased for the renovated agricultural building.
With the AC•THOR 9s, two 9 kW heating elements in Mr. Malinowski's weekend house are supplied with photovoltaic electricity. The two heating elements are installed in a 1500-liter buffer tank to store enough heat during the day, even in winter, so that the photovoltaic output can be used as best as possible to support the primary heating. The pellet heating system can provide the necessary temperature increase on days with insufficient photovoltaic output, but the sun's power can also be efficiently converted into heat in winter.
The special thing about it is that the 18 kW application can be implemented with just a 9 kW power manager. The AC•THOR 9s has a potential-free relay contact that is activated at a defined excess threshold. If there is enough excess, a second heating element can be switched on, and the first heating element continues to linearly regulate the photovoltaic surplus available for heat generation. This means that up to 18 kW of surplus can be used in the buffer storage with just one AC•THOR 9s.
Were there any obstacles during the setup?
According to the owner, there were no problems that could not be solved during the commissioning or setup of the AC•THOR 9s. Thanks to the uncomplicated help of the my-PV support team, the setup was easily carried out to the customer’s satisfaction.
Hot water demand of the people in the household?
In the building located slightly above the Upper Austrian Kremstal, three people do not live permanently, as it is used as a weekend house. Therefore, the demand for hot water and heating for living comfort fluctuates, especially seasonally and due to the non-permanent occupancy of the residence.
In winter, the hot water is heated using the buffer tank. In summer, the hot water is heated directly with a heating rod. Accordingly, the owners always have enough hot water available when needed.
A hot water backup is not used for the buffer tank since the primary heating system with the pellet heating system is already in place.
How the heating support works in the transitional period
An exemplary daily chart and the monthly evaluation in March 2023 show the advantages of solar-electric heat generation: Electricity from the photovoltaic system is predominantly used to heat the buffer storage instead of being fed into the grid. In this way, self-sufficiency can be increased, operating costs minimized, and self-consumption maximized at the same time.
Personal customer opinion and resumee
The beautifully renovated old farm with quarry stone walls is located at a wonderful location with a view of the Valley Kremstal in Upper Austria. The large roof areas offer a great alternative to a very expensive complete renovation, as the roof areas offer enough space for a large photovoltaic system. This solar power can be used to charge the buffer storage efficiently and continuously, especially in the cold months. The advantage for the owner is obvious: the heating costs are still manageable thanks to solar energy, and the purchase costs of the system are low. In this way, the pellet heating system can be supported and therefore protected.
The owner summarizes his experience as follows: “With the very high heat requirement and the large roof area, I made the most out of photovoltaic modules to heat efficiently with solar energy. my-PV was the best and easiest solution.”
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When the actual feed-in starts on a sunny day in March, heat production begins – continuously and depending on the surplus. The temperature in the buffer storage increases accordingly.
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Over the course of an entire month, the heat generation is apparent (in green, the output for the two 9 kW heating rods). Grid consumption (in blue) remained relatively low despite the season, thanks to the continuous control of the heating rod.
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Wie die Photovoltaikwärme im 400 Jahre alten Bauernhaus umgesetzt wurde?
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AC•THOR 9s
in use
Simple & efficient: AC•THOR 9s controls up to 3 electrical heat sources depending on the availability of PV energy and heat demand – for both hot water, as well as for space heating. It ensures your personal living comfort fully automatically.
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