SHANGHAI (Reuters) - China’s energy regulator has ordered local authorities to take heed of the grid capacity when selecting new wind power projects, in an attempt to ensure that no more than 5 percent of the electricity they generate is wasted, it said in a notice.

China’s renewable energy law compels grid firms to absorb the power generated by clean sources such as wind and solar. However, many projects have been left with inadequate grid access, a problem commonly known as “curtailment”.

Regulators have sought to manage the pace of construction in order to give grids more time to expand transmission capacity, but 12 percent of total generated wind power was still wasted last year, as well as 6 percent of solar, according to official figures.

The new guidelines published by China’s National Energy Administration on Thursday said priority should now be given to cross-regional wind power bases that can deliver electricity to different regional grids.

The projects should be backed by cross-regional power supply agreements as well as commitments from the end-user provinces to build the required transmission capacity.

Projects on unused and untaxed land will also be favored this year, the guidelines said, as well as those on established wind power bases, where weather conditions are most favorable and subsidies are not required.

From 2019, all large-scale onshore and offshore wind power plants must be subject to a competitive tender process, with bids based on construction costs as well as power prices, the regulator said. The tariff for each project must not exceed the benchmark set by the government.

Last month, environmental group Friends of Nature said it was suing two regional power grid companies for failing to abide by rules that require them to maximize purchases of renewable power.