Too much of a good thing? (Image Patrik Stollarz/AFP/Getty)

HARNESSING the sun’s energy could save the planet from climate change, an approach that Germany has readily adopted. Unfortunately, this enthusiasm for solar panels could overload the country’s ageing electricity grid.

Solar power is intermittent and can arrive in huge surges when the sun comes out. These most often happen near midday rather than when demand for power is high, such as in the evenings. A small surge can be accommodated by switching off conventional power station generators, to keep the overall supply to the grid the same. But if the solar power input is too large it will exceed demand even with all the generators switched off. Stephan Köhler, head of Germany’s energy agency, DENA, warned in an interview with the Berliner Zeitung on 17 October that at current rates of installation, solar capacity will soon reach those levels, and could trigger blackouts.

Subsidies have encouraged German citizens and businesses to install solar panels and sell surplus electricity to the grid at a premium. Uptake has been so rapid that solar capacity could reach 30 gigawatts, equal to the country’s weekend power consumption, by the end of next year. “We need to cap installation of new panels,” a spokesperson for DENA told New Scientist.

However, the German Solar Industry Federation rejects DENA’s concerns, claiming that extra solar energy takes the pressure off high-voltage power lines because it tends to be generated close to where it is used. The federation adds that the grid only needs to be strengthened in some rural areas where solar supply can exceed demand.


Germany’s problems highlight the perils of moving to renewables without adequate preparation. “You lose flexibility on the supply side, so you need to gain some on the demand side,” says Tim Green of Imperial College London, perhaps by encouraging people to charge their electric cars when the sun shines.

The best long-term solution is to install region-wide grids, says Tim Nuthall of the European Climate Foundation in Brussels, Belgium. “In Europe, you need a grid that balances the sun in the south with the wind in the north.”