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The Energiefabrik includes three charging stations for electric vehicles. The charging schedule and power source are selected and controlled automatically based on digitally stored travel plans. (Photo: Franz Roßmann)

If you have enough space for solar panels, then – with the right design, networking and control – you can take your energy supply system off the public grid entirely and enjoy a permanent reduction in energy costs. Using B&R control technology, Provitec has done just that. Its innovative concept for electrically self-sufficient buildings is perfect for logistics centers, office complexes, retail stores and other less energy-intensive enterprises.

When the new office and workshop complex opened for business, Provitec's managing director Robert Endress suffered some sleepless nights. Called "Die Energiefabrik" (The Energy Factory, or EnFa for short), the complex operates completely independently of the public power grid – thanks to the innovative energy supply system developed jointly by Provitec and builder-owner Friedhelm Widmann. The boldly futuristic design of this system was what had Endress on edge as the building began operation.

Yet, since the ribbon was cut in the summer of 2014, the building's supply network has yet to experience a single shortage or outage. For both Widmann and the companies leasing space in the complex, it's not only the reliable supply of energy, but also the cost savings that are decisive.

In the main control room, an IP65-rated Automation Panel 900 with 8.5" multi-touch screen serves as the operator interface for the Energiefabrik. (Photo: Franz Roßmann)
The Energiefabrik stores surplus energy in a battery bank with a capacity of 400 kilowatt-hours, which can then be tapped during periods of insufficient sunlight. (Photo: Franz Roßmann)

As low as 6 cents per kilowatt-hour

"With our design, a self-sustained energy supply system like this has electricity production costs ranging from 6 to 20 cents per kilowatt-hour, depending on the constellation of energy sources used," says Endress. "So in very many cases, it pays off even without government subsidies."

The Energiefabrik's 350 square meters of workshop space and 600 square meters of office space are supplied with electricity, heating and cooling from 100% renewable energy sources. The energy supply system is designed so effectively that it has no need for backup from the public grid, making the energy not only environmentally friendly, but also extremely inexpensive. Building owners also avoid the fees and taxes that some countries charge for solar power systems connected to the public power grid.

Solar panels may be on the outside of the building, but they play a central role in Provitec's Energiefabrik concept for autonomous building supply. (Photo: Provitec GmbH)

The right blend of sustainable sources

The building owes its energy autonomy to a custom blend of energy sources and storage media. The roof and facade are clad with solar panels that deliver a rated output of 112 kilowatts (under standardized testing conditions). Electricity that is not used immediately is stored in a battery bank with a capacity of 400 kilowatt-hours. This covers approximately 80% of the building's energy needs and stabilizes the supply of power.

During periods of insufficient sunlight, a biogas-fired combined heat and power (CHP) unit with an electrical output of 40 kilowatts kicks in. Three heat pumps are used to heat and cool the building's rooms. When the solar power runs low, thermal energy from the CHP unit can be used for heating.

Located just north of Stuttgart in Neuenstadt, this innovative energy supply system produces enough surplus energy to feed three charging stations for its fleet of four electric cars – at under 10 cents per kilowatt-hour.

Forecasted energy requirements

"Intelligent control of the individual components is essential to the efficiency and effectiveness of the system as a whole," emphasizes Endress. The ability to forecast energy supply and demand based on meteorological data plays a key role here. As does the evaluation of data from a project management system – which makes it possible to turn off the lights and reduce the temperature in unused rooms. The system also uses business trip schedules to coordinate the charging cycles for the fleet of electric vehicles with the goal of optimizing utilization of the various energy sources and avoiding bottlenecks.

The control system based on B&R hardware uses weather forecasts to predict energy requirements and select an appropriate mix of energy sources. (Photo: Franz Roßmann)

Convergence of disciplines

"One of the biggest challenges of this project," recalls Endress, "was bringing together data from disciplines as diverse as building automation, personnel management, weather forecasting and ERP systems."

The higher-level controller that manages the system has to communicate with numerous interfaces and data formats, allow database connections and be able to handle certain tasks from the control components. To solve these demanding requirements, Provitec called on its extensive experience from dozens of automation projects as well as its experience programming and implementing the Prodaisi MES system, on which it based the new Proenergic energy management solution.

As the hardware platform for its database-intensive software, Provitec's engineers quickly zeroed in on the Automation PC 910 from B&R, an industrial PC that packs immense processing power in a small form factor. For the higher-level controller, Provitec selected a top-hat rail mounted CPU from the modular X20 system, which manages various system components ranging from the heat pumps and charging stations to the lighting. It communicates via POWERLINK with three X20 substations that have a total of 440 I/O points distributed throughout the building.

The operator panel in the control room is pendant-mounted on a swing arm and is based on an IP65-rated Automation Panel 900 with 18.5" multi-touch screen and stainless steel housing. It is also possible to control the system remotely via the Internet.

"We're convinced that the B&R solution gives us more technical possibilities than we would have with the competition. Nevertheless, the biggest advantage with B&R is the quality of their service. With all the difficulties that you'd expect to run into in the course of such a complex undertaking, B&R never once failed to come through." Robert Endress, Managing Director, Provitec GmbH

The right controller for any situation

"B&R's control technology offers the openness and flexibility we need to accommodate all our different interfaces and data formats," adds Endress. Yet that wasn't the only reason B&R was able to establish itself as the clear choice so early in the planning phase. At least equally important was the effortless scalability offered by the fine-grained portfolio of fully interoperable industrial control modules. "It allows us to cover the full spectrum – from the very simple to the highly complex."

The automation expert also praises B&R's integrated engineering environment: "We've grown along with Automation Studio, so it might be easy to take for granted how powerful it is and how much it simplifies our work."

Even on rainy days, the Energiefabrik's energy supply system provides enough power for a fleet of electric vehicles. (Photo: Franz Roßmann)

Faster results

Endress appreciates the many details that contribute to streamlining the engineering process, such as an integrated web server and SQL interface that give the controller direct access to databases and ERP systems without the hassle of programming the access from the ground up or purchasing it separately.

"We're convinced that the B&R solution gives us more technical possibilities than we would have with the competition. Nevertheless, the biggest advantage with B&R is the quality of their service. With all the difficulties that you'd expect to run into in the course of such a complex undertaking, B&R never once failed to come through."

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