The useful-heat cost of direct electric resistance is approximately the electricity price per kWh. For pellets, both the fuel's energy content and appliance efficiency determine useful heat produced.
Example
A 15 kg pellet bag at €4.99, 4.7 kWh/kg and an efficiency of 85% yields an estimated 59.9 kWh of useful heat, or around €0.083 per kWh. At €0.21 per kWh, direct electric heating would cost around 2.5 times as much in variable energy for the same useful heat.
Costs for equipment, auxiliary electricity, maintenance, ventilation and fuel delivery are excluded. Actual consumption is not guaranteed.