The solar roof at the Floriade Exhibition Hall in the Netherlands still holds the record as the largest of its kind in the world. The roof is comprised of 20,000 semi-transparent solar modules, and it has a surface area of 28,000 square meters (almost 7 acres). It acts as one gigantic solar panel, and generating 2.3 megawatts of power. The solar cells also provide a dappled shade beneath the canopy, which housed a huge exhibit of flowers, plants and trees.
The hall was was built by Nuon for the 2002 Floriade flower exhibition in Haarlemmermeer, just west of Amsterdam. Siemens Netherlands was responsible for the actually installation of the panels.
The Floriade exhibit is held only once every ten years, so the electricity is currently being sold to the grid. The yield of the solar roof is enough to supply 450 households with clean electricity (about 1.23 GWh per year). The solar roof is expected to have a 20-year lifespan, before it needs to be replaced.