If you could save solar power in the long term, photovoltaic systems would be more effective. (Photo: 3dfoto / Thinkstock)
Read out In retrospect, the matter is clear: 2010 to 2012 were the golden years of photovoltaics. Three years in which almost two-thirds of the systems installed today were installed - 7.5 gigawatts per year. In the meantime, there is little left over from the gold rush mood in the solar industry. Fortunately, the next driver of the energy transition is at the start: the battery.

The reason for the strengthening of the batteries is like the solar power 2010, the love money. If a household withdraws its electricity from the grid today, it pays around 25 cents per kilowatt hour. The same amount of electricity from a cell from the roof costs about half. This benefits especially who has a battery in the basement. Because it enables a household to use about 60 percent of its self-produced electricity itself. Without a battery, the proportion is just 30 percent.

The signs that the industry is picking up are multiplying: There are now more than 15, 000 battery systems in German cellars. For more than 10, 000 of them, their owners have used a loan from the Kreditanstalt für Wiederaufbau to finance them. The credit also attracts with good conditions; it is combined with a government repayment subsidy of up to 30 percent of the loan volume. At the same time, the price of batteries drops. In the last year by about a quarter, in the next two years experts expect another ten percent per year.

Car companies invest in electricity storage

This clear trend has meanwhile also been recognized by German companies. After Tesla and BMW have long been investing in the development of stationary storage, announced last week, Daimler, until the end of the year to deliver customers of the southern German energy company EnBW Heimspeicher.

In addition to the large car manufacturers, some smaller companies are currently positioning themselves on the market, which want to channel the homeowners' electricity with different business models into their batteries. For example, the electricity bank wants to create large capacities in central storage servers, which are then leased to customers on a piece-by-piece basis. The Swiss companies Fenecon and Ampard, however, want to combine several home storage into a virtual network and offer its performance as a control current, so to bridge short voltage dips in the network. display

Electricity from the basement

In the meantime, researchers are also gathering together what belongs together: In the recently published industry guideline "Solar.Strom.Speicher 2015" of the German Cleantech Institute, photovoltaic and battery storage are discussed together for the first time. In cooperation with the Karlsruhe Institute of Technology, the Helmholtz Institute for Electrochemical Energy Storage in Ulm has installed a massive 76-kilowatt-hour battery in the basement, which ensures that the entire production of the in-house photovoltaic system itself can be used.

The approaches are diverse and, no matter which model will prevail, the next years belong to the battery. Maybe thanks to her, the solar system will get a boost again. For one thing, the battery, despite its new strength, can not recharge itself.

© science.de - Felix Austen
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