German solar battery maker Sonnen qualifies to provide grid services

German solar battery maker, Sonnen, has won approval to join the lucrative market for keeping the country’s power network in balance, giving a boost to its drive to reach profitability.

Jean-Baptiste Cornefert, head of Sonnen’s eServices retail unit, told media it had been accepted by Germany’s biggest power grid firm TenneT to join the so-called balancing marke.

It joined the market in which companies compete in auctions to either deliver power or take it into storage to keep the system balanced.

Sonnen will start bidding in so-called primary balancing power auctions from next week by pooling the power generation and storage of its thousands of small customers, he said.

“For the first time, a big network of home storage systems becomes a protagonist in the energy market,” Cornefert said.

The move will put Sonnen in competition with 25 German power firms, including big players RWE and Uniper.

Sonnen, which secured 60 million euros (71 million dollars) in May from Shell Ventures and existing shareholders to expand at home and abroad.

It has sold around 30,000 battery storage systems to German households with rooftop solar panels.

While its customers typically consume 70 per cent of the power they produce themselves, the batteries help them store power for later use.

It releases it to the public grid, or share it with other Sonnen community members in an online network.

Joining the balancing market provides another option with the company set to offer one megawatt (MW) blocks of flexible production or storage, up to a maximum 100 MW, it said.

That only equates to a small fossil-fuel power plant, but has potential to expand as storage becomes cheaper and generation becomes less centralised.

Germany has 1.5 million solar systems whose subsidised sales tariffs are due to be phased out in the coming years.

Providing balancing power is becoming more important.

As more variable renewable power capacity is built in Germany’s drive to become a lower-carbon economy, drops or surges in grid frequencies are becoming faster and more intense.

Grid frequencies must not deviate too far from around 50 Hertz to keep flows on power transmission lines intact.

Control measures taken by grid managers entail adjustments within 30 seconds, currently earning operators potentially around 100,000-150,000 euros per MW per year.

Cornefert said Sonnen might pay back earnings from the balancing market to customers in the form of entitlements to free power.