Spain-based Telefonica’s new office complex in Madrid is expected to have the largest European solar power plant on a building, UPI reports (via TreeHugger).

Company officials say their new Madrid office complex will have more than 16,000 solar panels and will be able to generate approximately 3 mega-watts at peak power, which translates into over 3.6 gigawatt hours per year.

Officials estimate that the design will enable Telefonica to reduce their winter heating bill by 15 percent. They will see a 34 percent reduction in air conditioning during the summer months.