The issue will grow in importance as the country's supply of electricity from renewables moves from 20% in 2011 to 35% by 2020.
The electricity system is as stable as ever for normal consumers, but companies using large amounts of electricity complain that even voltage drops for fractions of a second can seriously upset complex computer-controlled industrial production processes.
In December, Norwegian aluminium company Norsk Hydro, which reported annual revenues of around EUR2.3 billion in Germany in 2010, complained to federal energy regulator Bundesnetzagentur about electricity supply problems last year at its production locations in Hamburg, Hanover, Neuss, Grevenbroich and Rackwitz.
"We originally invested in Germany because it was a matter of course that electricity supply was secure - a very important factor for our plants," said Michael Peter Steffen, Norsk Hydro's communication manager at Grevenbroich. "But we experienced more interruptions - of milliseconds but also outages of one and a half hours - in the period July to November 2011 than we had in the last decade."
This cost up to EUR500,000, according to Steffen. "We reported the situation to the regulator and have requested talks to establish who is responsible for paying such costs," he added.
Roland Schmied, spokesman for the federation of industrial energy consumers, VIK, said: "The problems cannot yet be fully quantified. We have launched a survey of industrial power users, the results of which may be available in February or March."
Network problems have been slowly building up over the past few years rather than being a sudden phenomenon, VIK believes. "We think noticeable changes probably began in about 2005, when renewables expansion started to become significant," he said.
"Until now, the quality of electricity supplies to industrial customers has not been an issue," said Eberhard von Rottenburg, an energy expert at the German Industry Federation, the BDI. "The discussion is just beginning.
"German electricity supply has been seen as one of the big advantages of locating industry in this country," von Rottenburg added. "The situation could now be more difficult, and industrial electricity consumers, the electricity sector and the government have to decide on the way forward. There are technical solutions - but they can be very expensive."
He continued: "We are still at the fact-finding stage. We see a massive increase in feed-in of wind and solar electricity and there is a radical increase in electricity market volatility. We must see to what extent there is a correlation between the two, and what remedial measures can be taken, for instance at distribution network level."
For instance, the distribution networks must be made smarter and able to handle bi-directional flows, where wind and solar generation would feed in at the network perimeters for transmission to consumers, and in the other direction when the wind is not blowing and the sun not shining. There is as yet no masterplan on this, but the discussion will intensify this year, he said.
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