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PV Tech Storage interviewed Wolfram Walter, head of residential energy storage company ASD Sonnenspeicher (‘ASD Sunstorage’) at Intersolar Europe in June this year. During the course of the interview, Walter said that his company had been launched from what he saw as necessity. According to Walter, he could not find a residential storage product that he was happy to couple with his own PV system, so he built one. Walter says that this pet project subsequently snowballed, with ASD launching its systems commercially and along the way, he says, he has turned his Porsche Boxster sports car into an EV and his house into a smart home.

Five years ago, he built his own 160kWp solar installation on the roof of his aircraft hangar, followed by a 5.6kWp system on his home in southern Germany. He was happy with this second installation for a grand total of four days before it turned into a source of major frustration, he says. During the day, Walter’s private PV system produced 4,000W of electricity, 3,600W of which he was able to sell by feeding into the power grid. In the evening, however, he had to buy 1,000W from the grid, as he was unable to use the electricity generated by his system during daylight hours. He started to search for an energy storage system but says he was unable to find one that met his needs.

Instead, Walter, an engineering graduate, ended up building his own storage system for use at both his home and the flying school he runs. And he was satisfied with his work. What he hadn’t expected, however, was that his flying students, senior members of staff at a solar company based in Freiburg, would show interest in the storage system.

“I was made an offer that I couldn’t refuse and which saw my business partner, wife and me spending every weekend and evening building storage systems,” explains Walter.

Best laid plans: The boss of an accidental storage company

Finding his lack of PV self-consumption to be a source of frustration, Wolfram Walter says he built his own storage systems for his aircraft hanger and home. Image: ASD Sonnenspeicher.

Burn out

The storage systems are controlled by a smart electronic system, storing solar energy and enabling an on-site consumption rate of over 90%. ASD claims that its products are made up of fewer components than those produced by their rivals, that ASD energy storage systems are particularly inexpensive to produce and typically cost 20 to 30% less than other lithium-ion batteries on the market.

It only takes one millisecond for the electronic device built into the storage system to switch between power grid and battery operation. By comparison, systems which are mechanically controlled take 20 to 30 milliseconds to switch over, resulting in short disruptions in the supply of power to appliances that are turned on in the home, which could, for example, lead to televisions losing their programming.

“I almost gave up over this issue, as finding a technical solution to the problem of switchover time didn’t come at all easily. Many thousands of euros of my own money literally went up in smoke during the development stage, such as when yet another relay burnt out,” says Walter.

The accidental storage company head originally worked in the field of measurement technology and went on to establish his own engineering company before fulfilling, at the age of 37, his lifelong dream of becoming a pilot. He subsequently founded a light aircraft flying school, trained 600 pilots and was three times named Germany’s light aircraft champion. He then developed a special measuring instrument that can be used to search for minerals from the air and built a further successful business on the back of this invention.

Best laid plans: The boss of an accidental storage company

Walter fills his self-made EV with PV-generated electricity. Image: ASD Sonnenspeicher.

Turning a Porsche into an EV and reaping the benefits

In addition to his passion for flying and the plane in his hangar, he also loves driving his Porsche. He converted his Porsche Boxster into an electric car himself. Having fitted it with ASD’s own battery, he drives around 16,000km each year and fuels it with solar power from his own PV installation.

 “I can quickly break down complicated interconnected issues into simple questions and I’m then usually able to find straightforward answers to complex technical problems. I wouldn’t say that I am proud of what I’ve achieved so far; it just all seems to have come about as a result of my frustration with particular problems having no ready-made solutions,” explains the 52-year old.

“Today’s storage system market is still far too small, as only a few people can afford to invest in such technology due to it not yet being cost-effective. But I intend to change this. We’re currently working on a storage system that is so economical it will attract the attention of an entirely new group of buyers.”

Best laid plans: The boss of an accidental storage company

The latest residential storage system from ASD, complete with coloured light display in place of an LED panel. In developing the first battery systems, "Many thousands of euros of my own money literally went up in smoke during the development stage, such as when yet another relay burnt out,” says Walter. Image: ASD Sonnenspeicher.

Tags: pv, self-consumption, lithium iron phosphate, asd sonnenspeicher, porsche, boxster, on-site consumption, ev, smart house