Space heating with AC•THOR 9s
Heating with photovoltaic power in a commercial building
Electric heating elements use surplus PV power to heat 4,000 liters of buffer storage for space heating in a commercial hall.
Facts about the project
- Owner/Planner/Installer
- Location
- Photovoltaic output and orientation
- Building type
- Year of construction and size
- Heat storage size
- Inverter and battery storage
- my-PV product
- Heating rod (my-PV, other provider, etc.)
- System control
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Why a commercial hall is ideal for PV heating
A commercial hall in the south of Munich offers plenty of space for installing a photovoltaic system. In addition to the advantage of generating their own electricity and self-consuming power from the hall’s roof, the owners, the Keussen family, wanted to make even better use of their PV power. Although daytime operating electricity was already largely covered, a significant amount of the total 120 kWp PV output (99.96 kWp on the roof, 21 kWp on the façade) was still being fed into the public grid at low remuneration rates.
During an event in the hall, with Prof. Dipl.-Ing. Timo Leukefeld, an infrared heating manufacturer (Heatscope), and my-PV, the PV heat specialist, present, the owner had the idea to maximize self-consumption. The 1,800 m² hall, built in 2001, has a large heating demand. The building already had two Fröling stratified storage tanks, each holding 2,000 liters. Until the PV heating project, a pellet boiler produced all the heat year-round. Domestic hot water is produced separately, since the demand is low for the 15 employees — no notable consumption.
Personal customer opinion and resumee
“We advise our clients on the concept of the fully electric building (3lectrify all electric building), so we must demonstrate consistent sector coupling at the building itself. It will become even more interesting in the next expansion stage, when we integrate a much larger storage system, an energy management system that incorporates dynamic electricity tariffs, and bidirectional charging for our vehicles. We also plan to install a public solar charging station for external HPC charging,” summarizes the resourceful Bavarian.
The large storage volume offered by the tanks was perfect for use: two my-PV screw-in immersion heaters, each with a 9 kW heating capacity, transfer heat into the tanks. The heaters are controlled by two AC•THOR 9s photovoltaic power managers. The key point is that only surplus PV electricity — power that would otherwise be fed into the grid — is used for heating. For this, surplus measurement is essential; otherwise, grid electricity could be consumed. After initial difficulties with the SolarEdge system, surplus measurement was implemented using a my-PV WiFi Meter. Thanks to the AC•THOR 9s’ continuous power control, every available watt is utilized — unlike stepped control systems, nothing is wasted.
Where’s the advantage of PV heating?
In the transitional seasons, the pellet boiler can be almost entirely switched off. The two 2,000-liter buffer tanks store enough heat to cover several days without PV surplus. Thanks to the east-west alignment, surplus PV power is available throughout the day. Even in winter, the partially vertical PV system produces notable yields. Any electricity not used directly in the hall is stored as heat — regulated linearly by the AC•THOR 9s units.
Heat use for private housing
A special feature of this commercial hall is that the heating network is also connected to two neighboring semi-detached houses, which are supplied from the total 4,000 liters of storage. This way, PV energy generated on the hall’s roof can also benefit the neighborhood.
Were there any hurdles during installation?
“As mentioned, the SolarEdge inverter signal was unfortunately not compatible with the application — even though the two companies are officially compatible,” says hall owner Lars Keussen. This could be due to several factors; determining the cause afterward is difficult. In any case, the surplus measurement with the my-PV WiFi Meter provided an affordable and precise real-time control solution.
A small additional delay was caused by insufficient circuit protection for the heaters, but this was quickly resolved by the electrician.
What are the benefits of PV heating?
“In my opinion, the benefits of PV heating are obvious and manifold: self-consumption increases dramatically, the pellet boiler is relieved, fewer pellets need to be purchased. There’s also the consistent sector coupling, as electrical energy flows into various sectors: mobility, heating, household electricity, and even cooling in summer,” says Mr. Keussen.
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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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