The rooftop photovoltaic system, comprising 15,000 panels, is capable of producing enough electricity for 1,350 households — 4.2 gigawatt-hours per year.
Covering 15,000 square metres, the solar project is three times bigger than the previous biggest such installation in the country.
The Services Industriels de Genève (SIG), the state-owned utility, invested 15 million francs ($16 million) in the new system, boosting its output of solar power by 50 percent in the process.
In a statement, Palexpo said that it and SIG wanted in the planning process to ensure the electricity produced by the installation would be affordable — less than 50 centimes a kilowatt-hour.
In fact, it said the cost is 33 centimes, while the system is designed to produce 30 percent of the exhibition centre’s annual power needs.
Engineers faced a number of challenges in retrofitting Palexpo’s roof to accommodate the solar panels and associated electrical equipment, which weigh a total of 560 tonnes.
The roof had to be reinforced to carry the weight of the installation.
“With a photovoltaic panel surface per resident three times more than the national average, Geneva is positioning itself at the head of Swiss cantons,” said Pierre Maudet, Geneva cabinet minister responsible for energy.
The project fits in with a policy adopted by the canton to promote renewable energy whenever possible.
The Palexpo installation has more than double the capacity of one at the Federal Institute for Technology at Lausanne (EPFL), which previously held the Swiss record with an output of two gigawatt-hours per year.