Posted on 16 December 2013 by CompareMySolar. Comparison of nPower rates per kWh for currently available electricity tariffs. Following our price comparison of standard electricity rates of the big six suppliers, we focus on all available rates from nPower: Standard, Price Fix April 2015, Price Protector December 2017.osted on 16 December 2013 by CompareMySolar. Comparison of nPower rates per kWh for currently available electricity tariffs. Following our price comparison of standard electricity rates of the big six suppliers, we focus on all available rates from nPower: Standard, Price Fix April 2015, Price Protector December 2017.