Arwen Colell was cycling down a Berlin street one afternoon when a friend from her choir group called her and said: "We should buy the electrical grid." The idea was not out of the blue. Germany's energy transition, from nuclear and fossil fuels to renewables, has lined rooftops with solar panels. But it was another ambition to run Berlin's distribution network.

Colell did not hesitate. "We should definitely do it," she said. "Good idea."

Since that conversation in 2011, Colell and her friend, who are in their mid-20s, have built a movement aimed at putting the city grid under citizens' control when the system goes on sale next year. The grid is owned by the Swedish firm Vattenfall.

The co-operative founded by the two students, Citizen Energy Berlin, has recruited around 1,000 members, each paying a minimum of €500 (£430) a share. It has raised €5.4m (£4.6m).

The fundraising has some distance to go. A Berlin civic report valued the system at €800m; Vattenfall claimed it is worth €3bn. And the co-operative faces stiff competition from other bids, including one from Vattenfall.

The Berlin senate will make a decision next year, based on financial resources and capacity to manage the grid. The winner will run the system from 2015 to 2035.

Taking control of the grid is an idea whose time has come. Activists in Hamburg and other cities have launched similar campaigns to regain control of their local grid. In the Black Forest region, a residents' co-operative in Schönau has been running the grid since the 1990s. "Schönau is showing us the way," said Colell.

There is broad support in Germany for the goals of the energy transition, or energiewende: cutting coal usage and phasing out nuclear reactors by 2022, while reducing greenhouse gas emissions. The plan is to cut the country's emissions by 40% by the end of the decade, and by up to 95% by 2050.

Germany generates a quarter of its electricity from renewable energy. On one bright sunny day in June, wind and solar provided 60% of its power needs.

However, the transition is patchy – with some parts of the country still dependent on highly polluting brown coal – and Germans bear the cost with high electricity bills.

The Berlin grid, the country's largest, gets more than 90% of its electricity from coal. That is much too high if Germany is to meet its climate-change goals, or the renewable targets of its energy transition, Colell said.

"We need this element of strengthening the voice of citizens in the landscape of energy utilities. It is still very much divided up between the big energy companies. Citizens do not really have a strong voice."

She said big firms such as Vattenfall had failed to move fast enough on renewables or energy efficiency, and were unsuited to more decentralised generation of electricity from rooftop solar and small-scale wind projects.

About 40% of Germany's renewable energy is generated by small-scale producers. Farmers alone provide 11%, and there is a growing movement of energy-producing co-operatives – a four-fold rise since 2009 to 735 – most of which generate solar power.

But the big four energy companies between them produce just 6.5% of the country's renewable electricity.

If Berliners bought back their grid, Colell said, they could put profits back into the system and speed the take-up of renewables and deployment of smart metres.

The idea of control has strong attraction for some Berliners. For Annette Jensen, who recently moved into a new flat in Berlin, regaining local control of the grid was critical.

Jensen's was one of the first passive buildings in the city. Its four levels of insulation, triple-paned windows and array of solar panels on the roof means that residents could, on sunny days, be selling power to the grid.

"After the financial crisis, we wanted to put what small money we had into a flat, we didn't want to be dependent on some big energy company," Jensen said.

Research based on a study trip organised by the Centre for Strategic and International Studies, Washington, the Heinrich Boll Foundation and German foreign ministry.