(Bloomberg) -- Germany will allow onshore-wind developers to ditch contracts after a surge in costs made some projects unviable.

Around 5 gigawatts of onshore projects awarded with subsidies in the past two years haven’t been built, the Economy Ministry said as it announced the move. Inflation has dogged the industry and investments are stalling, it said.

The failure of developers to bring plans to fruition has cast doubt on Germany’s program for a huge buildout of renewable energy. Wind farms in the country — and around the world — are seeing investment foundations crumble amid soaring costs for materials and rising interest rates.

The “exceptionally sharp rise in costs” wasn’t foreseeable when the bids were submitted, the ministry said Wednesday in a statement. The government is keen for developers to tender for new contracts, with higher costs now better reflected in rates agreed last December.

The 5 gigawatts of unbuilt onshore wind roughly equates to the capacity of Germany’s last three nuclear plants that were shut down in April. Europe’s largest economy, still struggling to replace Russian gas, faces a monumental task to ramp up renewable power to the targeted 80% of generation by 2030.

Rocketing costs have also affected offshore wind, with around 6 gigawatts of projects proposed off Germany’s coast not moving ahead as planned.

Solar developers, too, have faced hurdles, particularly in connecting new installations to the grid. The government on Wednesday moved to ease the problem, saying plants of as much as 50 kilowatts can be linked up if there’s sufficient capacity and the network operator doesn’t respond to a connection request within one month.

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