CHENNAI (Reuters) - India’s coal-fired electricity generation so far this month fell 1.5% from year earlier, while power output from renewable energy jumped 53.6%, a Reuters analysis of government data showed. The slowdown in coal-fired power output and a pickup in renewable energy generation could provide relief to utilities across the country which are struggling with a coal shortage, forcing India to ask power plants to import coal.Overall electricity generation growth slowed to 1% in the first half of September, a review of daily load despatch data by federal grid regulator POSOCO showed, much slower than the 16.1% growth in August which had resulted in a 23.7% increase in coal-fired output. The steep increase in coal-fired generation in August pushed average coal stock held by Indian coal-fired plants down to just six days’ needs as of Sept. 13, a near three-year low, compared with an April 2020 high of stocks lasting 31 days, latest federal power ministry data showed. Federal guidelines mandate utilities have stockpiles that last at least two weeks. Renewable energy output rose 53.6% in September, driven by a more than doubling of wind power production and an 18.6% rise in solar power generation, the POSOCO data showed, making up for a 5.3% fall in hydro power output, and a 33.7% decline in gas-fired power. The share of coal in India’s overall electricity output fell to 65.7% in the first half of September, compared with 66.5% in August, the data showed. The share of renewables rose to 12.1% from 11.9% in August.