Leimholz Haag trades in timber and timber construction products, processes them and handles the technical planning, supplying customers across Switzerland from its base in Steinach. The family company’s saws, presses and planers are hungry for electricity, and since June 2025 a SolarEdge rooftop system has covered around 54 percent of demand. According to the two companies, that saves about CHF 35,000 a year in energy costs and avoids roughly 235 tonnes of CO₂.
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Safety first, for good reason
Leimholz Haag knows what is at stake when wood and electricity meet. Its previous premises on the Saurer site in Arbon burned down in 2012, and the Steinach plant followed a year later. Wood is stored and processed there in large volumes, which is why fire protection came first when the PV system was planned.
An arc at a faulty connector can reach temperatures high enough to ignite a roof, and the system is designed to detect such faults and interrupt them immediately. It is also fitted with SolarEdge’s SafeDC function, which brings the high DC voltage of the array down to touch-safe levels whenever the inverter or the grid is switched off. That makes work safer for maintenance staff and firefighters. Solar power also feeds fire protection directly, since the plant produces its own nitrogen as part of its fire protection strategy and runs that process on electricity from the roof.
A tower that casts a long shadow
Planning was complicated by the roofs themselves, which are spread over several buildings with different heights and orientations, including east- and west-facing surfaces. A 25 m storage tower also throws moving shadows across the lower roofs during the day. Installer CE Concept Energy used SolarEdge’s DC-optimised inverter technology to limit the losses. Power optimisers under each pair of modules let the modules work independently of the others in the same string, so a shaded module does not pull down the output of the whole string.
Two batteries, two jobs
This autumn the company is installing two SolarEdge CSS-OD commercial batteries with 197 kWh each, or 394 kWh in total. They store surplus solar power from periods of low demand and release it when consumption rises, which should lift self-consumption to 72 percent. SolarEdge ONE, the manufacturer’s AI-based energy management system, monitors generation, consumption and battery performance and controls the batteries on that basis. The second aim is peak shaving, which means cutting the short spikes in grid demand that drive up power bills.
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“Several energy-intensive machines run at the same time in our plant. If we use stored solar power to reduce load peaks, we can cut our electricity costs considerably,” said Peter Haag, managing director of Leimholz Haag.
Martin Mäder, co-owner of CE Concept Energy, says projects like this are becoming more common. “Leimholz Haag’s investment shows how strongly demand for commercial storage is growing. More and more companies want to reduce their dependence on the grid and get more out of their own solar power at a time of high energy costs,” he said. For the installer, he added, a single technology supplier for PV, storage and energy management makes the whole system easier to plan, commission and manage. (TF)
