The solar eclipse on Wednesday threatened a shortage in electricity that prompted the national grid to call on an emergency power plant to ensure adequate supplies, it has emerged.National electricity grid operator EirGrid drafted in an emergency power plant in Tarbert, Co Clare, after the eclipse shut the solar farms that have been supplying large amounts of electricity this summer.The increased risk of a shortage in electricity sparked a warning to suppliers on Wednesday evening that ran from 6.55pm, shortly before the partial eclipse began, to 8.21pm, around an hour after it passed.Wednesday’s hot weather increased demand for electricity, EirGrid said in a statement confirming the squeeze on power supplies.A lack of wind cut off the other main source of renewable electricity on which the system normally relies.Meanwhile, the temporary shut down of three large power plants for routine maintenance, and low imports from Britain, which supplies 12 per cent of Irish electricity, added to the pressure, EirGrid said.“Wind generation was low and solar generation dropped to near zero during the solar eclipse,” the company said.EirGrid said it had prepared for the eclipse, putting plans in place to ensure continued electricity supplies.The Single Electricity Market Operator, which is responsible for overseeing the Irish power market, issued a “margin warning” on Wednesday evening and told suppliers that EirGrid had deployed the emergency generator.However, the warning did not move to “alert stage”, which would have signalled increased risks to electricity supplies.The operator issues such warnings when electricity consumption has reached a point where the buffer between available supply and likely demand is tighter than it should be. They do not signal that power cuts are imminent.EirGrid operator commissioned four “temporary emergency generators” in Dublin, Co Clare and the midlands several years ago as demand for electricity outpaced supplies after delays in building planned power stations.The company intended them as a backstop to supplies during times of peak winter demand.EirGrid confirmed that Wednesday was the first time it called on the Tarbert emergency power plant to provide electricity. The plant produces 150 megawatts of electricity.News of the warning and deployment of the emergency generator comes against a background of increasing concerns about security of electricity supplies and bottlenecks in the network itself.Rising demand prompted a series of “amber warnings” of increased pressure on electricity reserves during peak demand times through several winters at the start of the decade.The four temporary plants, which have so far cost around €1 billion, were part of a response to this orchestrated by industry overseer, the Commission for Regulation of Utilities.