Which of the following statements about rooftop PV systems is false? Group of answer choices At present, the high cost of energy storage for times when the sun isn't shining has made the use of rooftop PV systems impractical. Germany leads the world in sales of rooftop PV systems. Photovoltaic systems for homes can be mounted either on the ground or on rooftops. High up-front costs are the major deterrent to wider use of rooftop PV systems. New solar technologies utilizing thin films rather than flat panels are expected to reduce costs and provide higher conversion efficiencies in the near future