A metal parts manufacturer in southwest Germany pays 1.6 cents per kilowatt hour for electricity and 2.5 cents for heating and cooling. Those numbers are not rounding errors. The company, MEA, which produces fastening and mounting systems and employs around 200 people, built its factory from the start around a system that uses no gas connection at all. Solar thermal collectors on the roof and south-facing facade capture heat during summer. That heat travels down to 240 ground absorbers buried in narrow ditches beneath the building, charging more than 5,000 cubic meters of soil to around 23 degrees Celsius by the end of summer. Through winter, heat pumps pull that stored warmth back out and circulate it through 45 kilometers of pipes embedded in the concrete foundation, keeping production areas and office spaces at a consistent working temperature.
The core innovation is that the solar collectors double as air absorbers. When sunlight is not available, the panels still extract warmth from ambient air using a water-glycol mixture called brine, functioning like the outdoor unit of a conventional air-to-water heat pump. This matters because it extends useful collection hours well beyond sunny days. The building also carries more than 1,800 photovoltaic panels with a peak electrical output of 750 kilowatts, covering production and operations needs. The PV panels are mounted directly above the solar thermal collectors, and the heat rising from the solar panels pre-warms the collectors below them, increasing the energy yield per square meter. Excess electricity flows back to the grid. The company says its on-site PV generates roughly 30 percent of the facility's electricity requirements.
Three heat pumps coordinate the full system, and their operation is tied to a weather forecast feed. On clear winter days, the system deliberately overcharges the concrete core to 28 degrees Celsius, storing more heat than is immediately needed so that the pumps can stay off for several days if clouds move in. If temperatures drop below 2 degrees Celsius over an extended cold stretch and the concrete core cools, the ground absorbers take over as the heat source directly. Cooling is handled by a 60,000-liter water tank that stores cold produced as a byproduct of the heat pumps year-round. Machines in production and a server room draw from this tank rather than running dedicated cooling equipment. The owner states the entire system paid back its cost in three and a half years compared to a conventional gas or oil installation, and the AI-assisted control system continues to optimize across seasonal conditions.
Bottom line: This is what a fully committed renewable energy setup looks like at industrial scale, and the payback period is faster than most similar projects. The absence of a gas connection is not a gap in the design. It is the design.