National Grid's Underlying Monthly Rates for Standard Offer Residential Monthly Standard Offer Rates: January 2015 18.671 cents/kWh February 2015 17.770 cents/kWh March 2015 10.736 cents/kWh April 2015 8.069 cents/kWh May 2015 6.924 cents/kWh June 2015 7.764 cents/kWh Back to FAQ's