Professionally, Carsten Fischer operates on teeth and jawbones. Away from work, Mr. Fischer is passionate about generating heat and electricity for his home in North Rhine-Westphalia, entirely on his own.
He is almost completely independent of utility companies – even in winter – thanks to a solar collector, storage battery and an electricity-producing block heat power plant in his cellar. Mr. Fischer is now linked to the local energy grid only as a backup.
“I’ve got everything in my own hands,” he said.
It is no longer a far-fetched dream for homeowners to become their own energy suppliers. Expensive storage batteries – an essential element in energy independence – are rapidly dropping in price. They make it possible to store electricity generated by the sun for use in nighttime hours.
German business weekly WirtschaftsWoche asked energy consultants NRW to calculate how much self-suppliers would have to invest in home power plants to go off the grid – and how long it would take for their investments to pay off.
In the best-case scenario, homeowners can achieve 80-percent independence with systems that are paid off in 11 years. That requires a photovoltaic system combined with a heat pump and lithium storage battery. Total cost would be €34,000, or about $39,000.
The battery could be financed with a loan from the state KfW Bank, which pays €600 in subsidies for each kilowatt produced by solar roof generators. If an existing facility is improved, the subsidy rises to €660 per kilowatt.
Last year, the price of super-efficient lithium-ion batteries dropped 9 percent, while lead batteries fell almost 35 percent, according to EuPD Research. The decline in prices means home energy plants can pay for themselves more quickly, according to NRW.
More homeowners are seeking maximum energy independence – and that is stirring up the market.
According to energy agency expert Sven Kersten, these kinds of systems are suitable for well-insulated buildings with low heating requirements, which can be met solely by a heat pump and powered by rooftop electricity.
For even more energy independence, homeowners can attach a wind turbine to the roof, to harness energy in winter when sunlight is rare. Fuel cells and micro-block heat power plants are another option, but the increased autonomy comes at a higher price – these systems cost over €40,000.
Mr. Kersten explained the difficulties of generating electricity around the clock. At midday, rooftop solar cells often supply more electricity than is needed in the house. But in the early morning, when residents turn on their coffee machines and toasters, or in the evening, when they start their computers and watch television, next to no solar energy is generated.
In 2008, when Mr. Fischer and his wife first moved into their house, he installed a rooftop solar thermal generator to power the 200-square-meter space, or about 2,100 square feet.
In 2010, he added a photovoltaic facility that provides about 7,600 kilowatt-hours in sun-generated electricity annually. Then, three years later, he installed a lithium battery in the cellar. It can store up to 14 kilowatt-hours — enough to supply the family with electricity for two days. A small block heat power plant provides energy in winter, burning biogas to produce electricity and heat. The family can now meet all of its energy needs when the different components work together.
The oral surgeon has paid handsomely for this independence. He invested a total of €76,000. He also bought two electric cars, a Tesla S and Opel Ampera, as he can power up his cars at home too.
Strictly speaking, he isn't completely autonomous yet, because he still needs a gas connection for his cellar power plant. But he enjoys not being subject to the whims of energy providers – and helping protect the climate. The economics come second. “What I care about most is my sovereignty,” he said.
He is sure that his investment is paying off. Through Germany’s Renewable Energies Act, the government pays him about 22 cents for every self-generated kilowatt-hour. And he doesn’t have to buy them from the suppliers, which saves another 27 cents per kilowatt-hour. Altogether, that adds up to savings of around €4,000 per year in home energy.
According to Daniel Quack-Scheffen, a market analyst for EuPD Research, for the last 20 years, homeowners installed photovoltaic equipment on their roofs mostly because of the guaranteed government subsidy. These payments have declined dramatically, so the business model of guaranteed subsidies is no longer profitable.
Now, more homeowners are seeking maximum energy independence – and that is stirring up the market. The newest solar panels produce electricity for about 10 cents per kilowatt-hour – about a third of what many public power plants charge. Combine that the dropping battery prices, and, even with the storage costs, homeowners can still save money.
This article first appeared in WirtschaftsWoche. To contact the author: [email protected]