||Contrary to some popular notions, the landscape of a world relying on PV would be almost indistinguishable from the landscape we know today. There are three reasons for this. First, PV systems have siting advantages over other technologies. They can be put on roofs and can even be an integral part of a building, such as a skylight. Second, even ground-mounted PV collectors are efficient from the perspective of land use. Flat-plate PV technology is the most land-efficient means to produce renewable energy. Third, adequate sunlight is ubiquitous and often abundant, and present in predictable amounts almost everywhere. For example, in the United States, cities and residences cover about 140 million acres of land. The nation's energy requirements could be met simply by applying PV to 7% of this area - on roofs, on parking lots, along highway walls, on the sides of buildings, and in other dual-use scenarios. Not one single acre of new land would need to be appropriated to make PV the primary energy source.