BERLIN, GERMANY: Germany's large number of solar installations is still expanding too rapidly and must be restricted if the market is to be kept sustainable, German Environment Minister Norbert Roettgen said on Wednesday.

Roettgen said while the government had aimed for new installations of about 3 GW last year, the figure had reached 7.5 GW, despite cuts to subsidies over the last two years in what is the world's largest solar market.

"We need to reduce new installations," he said at an annual energy conference organised by German newspaper Handelsblatt. "Seven gigawatts (GW) a year is a no-go."

Boosted by lavish tariff incentives, Germany became the world's largest solar market by installations and a major market for sector bellwethers such as U.S.-based First Solar, China's Suntech, Norway's Renewable Energy Corp and Germany's SMA Solar.

However, Germany has been cutting tariffs in an effort to force the industry to lower costs faster and head off steep rises in energy bills for companies and households, which are required by law to pay the feed-in tariffs.

Solar power accounts for about 3 percent of Germany's energy mix but nearly half of the total 17.1 billion euros ($21.8 billion) paid for renewable energy by consumers.

German Economy Minister Philipp Roesler said on Tuesday it was time for a review after two decades of state support for wind, solar and other forms of renewable energy to safeguard the sector's competitiveness.