Guernsey Electricity managing director Alan Bates said the "price rise of this size was not ideal" but the fault had led to increased costs, which are now being passed on to customers.
"A fault at a base station near Aylsham led to it occurring across a number of sites across the area, which has meant there has been intermittent coverage, " he said.
The announcement follows the suspension of its shares earlier this month, after a fault with the vehicle's steering box led to over 400 of them being recalled.
He was reported as criticising the school meals campaign the TV chef led, but he told the Faculty of Public Health conference it was the government response that was at fault for being too bureaucratic rather than Mr Oliver's approach.