Tightening regulations throughout the world demand a reduction in fuel consumption and NOX emission levels, creating an increasing need for additional heat for SCR aftertreatment. A durable and low cost heating system is needed for vehicles with hybrid or 24Vdc electricity. Recent development efforts have resulted in much smaller and lower cost heating systems for electrical systems ranging from 350 to 24Vdc. Test results demonstrate the feasibility of reducing the size of the heater and the relationship of heater watt density to the amount of time required to heat the exhaust. Intelligent solid state switching enables the heater to be smaller without compromising durability.