Intelligently controlled PV heat
German master electrical contractor with a solar-powered company building
A solar power company from Lower Franconia heats its commercial building using continuously regulated PV electricity.
Facts about the project
- Owner
- Location
- Photovoltaic power, orientation
- Inverter, battery storage
- Hot water preparation
- Building type
- Year of construction and floor area
- Installed my-PV Product
- Heating system
- System control
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The path of becoming a PV flagship company
Heger Energietechnik GmbH was founded in 1994 as a traditional master electrical installation company. Located near Aschaffenburg in Großostheim, the business has now been active in the photovoltaic sector for over 25 years. Since 2013, the medium-sized company has operated under the name Heger Energietechnik, and since 2021 it has been part of the Fabrigroup based in Nuremberg. Today, around 36 employees - including 7 apprentices and 4 master electricians - drive the expansion of photovoltaic systems and energy storage solutions in the region. In addition, the company provides maintenance and service for PV systems and e-mobility charging stations, as well as a smaller share of general electrical work.
Managing director Andreas Heger aimed to transform his company headquarters into a showcase project for photovoltaic energy use - also to inspire customers through real-world demonstration. The building, completed in 2025, offers ideal conditions for this purpose, allowing visitors to experience the concept first-hand and be convinced by it directly.
In the search for a solution to maximize the use of photovoltaic electricity across all energy sectors (household electricity, hot water, heating, and e-mobility), the company turned to the Austrian specialist for photovoltaic heat, my-PV. This medium-sized company from Neuzeug in Upper Austria presented its concept of a solar-electric commercial building in 2021, featuring extremely low operating costs across all four sectors. In 2023, my-PV reported annual operating costs of just € 405.
Personal customer opinion and resumee
“From the very beginning of planning our new company building, it was clear to me: we don’t just want to talk about the energy transition - we want to actively implement it. That is why I specifically looked for a heating solution that is simple, efficient, and future-proof - without complex technology or high maintenance requirements. Our positive experience with infrared heating in the previous building further strengthened this direction,” says Andreas Heger, owner and managing director of Heger Energietechnik GmbH.
After the first heating season, he summarizes: “The indoor climate in our offices is exceptionally comfortable - the warmth feels even and natural. At the same time, the system impresses with its simplicity and reliability - no complex water-based systems, no unnecessary heat losses, and no hidden technical complexity.”
Economically, the concept is equally convincing: low investment costs, virtually no maintenance, and maximum utilization of self-generated PV electricity. “For me, this building is more than just a company headquarters - it is a true showcase project for the energy world of tomorrow. I would choose this path again at any time - and I can recommend it with full conviction.”
Direct electric heating instead of a conventional thermal system
This concept convinced Andreas Heger, who decided to implement a solar-electric energy system to fully benefit from its advantages. The company headquarters covers 1,650 m² across five levels, with approximately 1,000 m² dedicated to offices, social areas, and training rooms, while the remaining space is used for storage.
All floors are equipped with concrete core activation. A 30–50 cm thick concrete slab is used as a thermal storage mass. Within this structure, heating mats - specifically BRS heating mats from Etherma, an Austrian manufacturer - are embedded. These mats enable the concrete to act as a heat storage medium, absorbing and releasing energy over hours or even days.
For rapid heating of the warehouse areas, the system alone was too slow to respond. Therefore, after the initially planned 11 units of AC•THOR 9s, two additional units were installed later. These devices control Etherma infrared heaters in the hall to provide fast temperature response. In logistics areas, where doors are frequently opened, air temperature drops quickly - making underfloor heating alone too sluggish. The heating mats primarily serve to store PV energy in the building mass, while the rapid-response heaters handle short-term heating demands.
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Why a direct electric heating concept was chosen
The roof and façade of the building are equipped with photovoltaic modules, as expected for a company active in the PV sector. “The decisive impulse came from a reference project by my-PV, which demonstrated electric concrete core activation in combination with photovoltaics. Together with our large PV system - especially the façade modules for winter energy yield - it quickly became clear: this is our path,” explains Andreas Heger.
In total, the building achieves 158.16 kWp of PV capacity across roof and façade. The façade plays a particularly important role: while annual yield is slightly lower compared to roof systems, it significantly improves winter energy availability due to the low sun angle. This ensures that a substantial share of PV energy is available precisely when heating demand is highest.
Direct electric heating offers several advantages. It is significantly easier to integrate, highly robust, and requires minimal maintenance. Unlike heat pump systems with multiple mechanical components (e.g., compressors), which require regular servicing, heating mats are simple, durable, and low-maintenance.
Intelligent control is crucial
The company building of Heger Energietechnik GmbH features a 158 kWp photovoltaic system as well as an 80 kWh commercial battery storage system, which helps bridge periods of low solar generation. However, the key factor is the maximization of self-consumed PV electricity through the stepless control of all system components, such as heating. The heating mats from Etherma are continuously regulated by photovoltaic power managers - so-called AC•THOR 9s devices from the Austrian manufacturer my-PV. A total of 13 of these PV power managers enable individually adjustable temperature zones while also working together as a system to maximize the utilization of surplus photovoltaic energy.
PV electricity from the roof and façade is first used directly for on-site consumption within the commercial building. Any surplus energy is then stored in the commercial battery system. Once the battery is fully charged or if additional surplus remains, the heating system is activated -provided it is not the summer season. Domestic hot water is also generated electrically via instantaneous water heaters, although not exclusively using PV electricity.
The system’s ability to utilize only surplus PV energy - energy that would otherwise be fed into the grid at low compensation rates - is ensured by the open system architecture of my-PV. Due to the compatibility between my-PV and SMA Solar Technology, whose components are already integrated as inverters and storage systems, no additional metering devices are required.
The system also includes six SMA charging stations with 11/22 kW charging capacity, which are fully integrated and coordinated within the overall energy system. PV electricity is prioritized for all consumption sectors; however, electric vehicle charging can also draw from the grid when necessary. An additional 50 kW DC fast charger was installed in spring 2026.
On days with insufficient PV production, electricity is naturally also drawn from the public grid. When comparing the potentially higher operating costs of a solar-electric heating system with those of a heat pump, the solar-electric solution particularly stands out due to its significantly lower investment costs - so much lower that even with slightly higher electricity costs in winter, the overall concept remains economically viable.
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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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