Hans-Olof Nilsson from Sweden is an electrical engineer who used to work in the refrigeration and telecoms industries and now co-manages a clean energy consulting firm focusing on off-grid solar power and hydrogen storage solutions. A few years back, he decided to go off-grid, by storing solar energy in summer as hydrogen to keep warm in the cold Swedish winter. One day, he invited me to visit his house, which has more than 5,380 square feet (over 500 square meters) of space and is just 6.2 miles (10 kilometers) away from Gothenburg. 

Our tour of the property began outside his house, where it became clear the project was a continuous work-in-progress. He wanted to put a carport on the east side of it, while the remaining area was to be levelled and covered with grass. That is, all of it except for the driveway and parking space close to the house: They would be paved with concrete and asphalt. At the time, the building had been almost five years in the making and was basically finished, with a few of the technical installations to be upgraded in the near future.

The exterior walls have been covered with ceramic tiles by Tonality, a German manufacturer. The tiles have been mounted on vertical metal rails while leaving about an inch of space between them and the insulation material behind the wall cladding. This space provides good ventilation and avoids moisture buildup during construction. When touching the tiles, they feel surprisingly cool, despite the warmth of the midday sun. This is by no means accidental. Nilsson chose them because they provide superb air circulation and function as a heat repellent in summer, reducing the need for cooling the interior of the building – a climate shield that is virtually maintenance-free.

One large room, 23 feet high

When Nilsson and I stepped into his home, his wife was sitting at her work table on the balcony on the second floor – in a building that is almost one single space only. She is the architect who designed the layout and oversaw construction of the house. The living room extends around 23 feet (7 meters) or so up to the angled ceiling, where large, slowly rotating fans ensure that all sections of the huge room are kept at an even and pleasant temperature.

Many questions start popping up as one takes in the magnitude of Nilsson’s project, the most evident being how many and what kind of installations are required to run a house this size off the grid? Also, how much does it cost to become energy-independent? It seems I was not the first to ask, as Nilsson responded almost immediately by saying:

“A typical high-rise building in Sweden costs, on average, 32,000 Swedish crowns, or USD 3,690, per square meter. Ours came to 15 million in total. It has 500 square meters, so that makes 30,000 crowns a square meter.”

That’s an impressively low number considering the high-quality materials used throughout, plus the PV and thermal panels, as well as a significant number of controllers, inverters, tanks and other pieces of equipment. Almost all units and appliances are interconnected, by wires or tubes or both. In all, there are 9.3 miles (15 kilometers) of the latter and 93 miles (150 kilometers) of the former. All switches and sockets lead to control cabinets, of which there are seven, with a central unit located in the basement. Each can be individually programmed and is monitored by a KNX system.

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read more in H2-international April 2019