Eversource customers are looking at a 13% hike in electric supply rates starting January 1. Company officials say the increase works out to about $10 more per month for the average household using 700 kilowatt hours. The supply rate will climb to 12.64 cents per kilowatt hour, driven by higher wholesale power costs and winter demand. About 83% of Eversource customers are on standard service, meaning most will feel the bump once regulators sign off in the coming weeks.