Following the compromise agreement between Germany and the EU a day earlier on exemptions from paying a surcharge on energy bills to fund renewables, two German associations - one representing the solar industry, another consumers - said on April 9 said they may challenge the funding of the scheme in the country's constitutional court.

While energy intensive chemical producers that compete internationally and those generating their own on-site fossil fuel energy will largely retain their exemptions, households and small businesses that generate and consume solar energy for captive use will have to pay 50% of the surcharge under the rules of the amended renewable energy act (EEG) the German federal government begin hopes to have passed by the Bundestag (parliament) by summer.

The separate and unequal treatment violates the constitution's equal treatment principle and is incompatible with the legislation's purpose of promoting renewables, the industry grouping Bundesverband Solarwirtschaft (BSW-Solar) and the consumer association Verbraucherzentrale said.

"Large parts of industry will continue to be freed from the financing. Yet those who relieve the pressure on the environment with solar power will have to pay," noted Carsten Körnig, head of BSW. Verbraucherzentrale called the plan "absurd."

A court case could hold up the reform.

Consumers, solar and wind energy producers - the latter branch also will see state aid reduced under the latest plan - are not the only ones unhappy with the planned legislation. German plastics processors - less than 20% of whom qualify for the exemptions - also are at a disadvantage, the industry association Gesamtverband Kunststoffverarbeitende Industrie (GKV) said.

The high energy costs compared with rivals in other EU countries leave little scope for capital investment, GKV said. The organization called on the federal government to abandon renewables subsidies.

Meanwhile, an as yet unpublished study by a Hamburg-based energy think-tank is said to show that there is no cheaper way to shift the German energy mix toward renewables than the government's  plan. Adding that all costs, generating energy from coal and gas is "considerably more expensive" than solar or wind energy, a television station quoted the study as saying.