Widespread rainfall across China increased hydropower generation in June, easing a power crunch in most parts of the nation, the top planning agency said on Wednesday.

Nationwide daily hydropower output averaged 2.31 billion kilowatt-hours in the second 10 days of June, up 12.3 percent from the first 10 days, the National Development and Reform Commission said.

The rainfall, mainly in east and central China, increased hydropower production and also reduced the use of air-conditioners, easing supply shortages significantly in provinces like Zhejiang, Hunan and Anhui, the commission said.

Out of the 26 provinces served by the State Grid Corp of China, only Hebei and Shanxi had restricted power consumption since June 10, the NDRC said.

However, power supply remains tight in the five southern provinces, including Guangdong and Guangxi, due to low precipitation, high temperatures and tight coal supplies, the commission said.

The five provinces have rationed power as shortages reached 8.38GW on June 10, the NDRC said.

State Grid said last month the nation's peak power deficit could reach up to 40 gigawatts this summer, which would be the worst shortage in the country's history. China's power generation capacity was 960GW last year.

This year's power shortages began in March in parts of China amid rising demand and surging coal prices, prompting the government to raise power tariffs to spur power production and curb demand from energy-guzzling industries.

Separately, Germany-based Voith Hydro said its Shanghai company, a joint venture with Shanghai Electric Group, rolled out its first hydro turbine equipment yesterday for Xiluodu hydropower station, which will become China's second largest hydro project.