Solar Heat Sharing in Hamburg

In a project that is alleged to be unique in Europe, residents of a Hamburg housing development can now collect solar heat with their rooftop panels during the summer, deposit it in a public storage unit and withdraw it in the winter for heating. The project, of the German power and gas company E.ON, has the partial support of the German government. Although solar power sharing is an advanced concept, the idea of doing this also with solar heat is rather new.

The location of the project is a solar housing development in the Hamburg district of Bramfeld, constructed 15 years ago with 124 row houses, all with good insulation and solar panels on the roof. Heat for the houses, beyond what the sun provides, has been supplied by a grid from a concrete and stainless steel public heat storage unit. This facility can hold up to 4500 cubic meters of water, which often boils in the summer. It is largely underground, with only a small upper part of it visible. 

The water in the storage unit is heated partly by the sun and partly by more conventional means. But as of mid-2011 it also got the heat from the solar panels of the individual houses in the development. Owners of the houses can use the grid to, for a fee, deposit their heat in the public unit, sparing themselves the complexities of proper heat storage. They continue to own the heat and can withdraw it as needed. The savings from the project can run as high as 30%, since two-thirds of the energy the sun supplies comes between April and September, when there is no need to heat. 

“The combination of point-of-use production and central storage will be an essential element of tomorrow's energy supply,” said E.ON board member Dr. Dierk Paskert. “With this project E.ON is showing that it is already possible not only to feed renewable power into the grid but also heat.” The seven-million-euro project is being partly financed by Germany’s Federal Ministry for the Environment.

Ted Shoemaker, an American, first went to Germany as an Army officer, married a German woman and stayed on as a writer/editor. Now retired and based in Frankfurt, he keeps his hand in by acting as a correspondent for a number of American magazines.