Pellet heating systems for single-family houses are currently a strongly growing market; however pellet heating is seldom installed together with solar heating, though it is a promising combination. The present book is based on the author's doctoral thesis written at KTH, the Royal institute of Technology in Stockholm, Sweden and investigates how electrically heated single-family houses can be converted to pellet and solar heating systems. There is a strong focus on system design and how to design and operate the systems so that the annual system efficiency and solar gains can be maximized. Technologies for increasing the solar gains are DHW- units for hot water production and the use of hot water for heating of dishwashers and washing machines via a heat exchanger instead of electricity (heat-fed appliances. The possible reduction of CO- emissions by combining pellet heating with solar heating are also investigated. The method is based on measurements modeling and system simulations using the dynamic simulation program TRNSYS.