use, but considerably more expensive than conventional ground-mounted systems due to the more extensive steel posts, footings and racks, as well as additional labor costs. This can be reduced somewhat by using lower cost building materials like wood. PV canopies over parking lots can be used to provide electricity for charging electric vehicles. There is substantial potential area for PV on parking lots. As for example, there is a potential 3.1 MW for PV and 100 EV charging stations per U.S. Walmart Supercenter. Popular Science reports that solar canopies built above parking lots are an increasingly common sight around the U.S.— installed at university campuses, airports, and lots near commercial office buildings. France, however, is requiring all large parking lots to be covered by solar panels. Different canopy structures can also be used for agrivoltaics. Tracking Solar trackers increase the energy produced per module at the cost of mechanical complexity and increased need for maintenance. They sense the direction of the Sun and tilt or rotate the modules as needed for maximum exposure to the light. Alternatively, fixed racks can hold modules stationary throughout the day at a given tilt (zenith angle) and facing a given direction (azimuth angle). Tilt angles equivalent to an installation's latitude are common. Some systems may also adjust the tilt angle based on the time of year. On the other hand, east- and west-facing arrays (covering an east–west facing roof, for example) are commonly deployed. Even though such installations will not produce the maximum possible average power from the individual solar panels, the cost of the panels is now usually cheaper than the tracking mechanism and they can provided more economically valuable power during morning and evening peak demands than north or south facing systems. Building integrated Building-integrated photovoltaics (BIPV) are photovoltaic materials that are used to replace conventional building materials in parts of the building envelope such as the roof (tiles), skylights, or facades. They are increasingly being incorporated into the construction of new buildings as a principal or ancillary source of electrical power, although existing buildings may be retrofitted with BIPV modules as well. The advantage of integrated photovoltaics over more common non-integrated systems is that the initial cost can be offset by reducing the amount spent on building materials and labor that would normally be used to construct the part of the building that the BIPV modules replace. Building-adapted photovoltaics (BAPV) uses