Europe

ISAAC (formerly TISO) - Institute for Applied Sustainability to the Built Environment - http://www.isaac.supsi.ch/default.asp

Fraunhofer ISE - The Fraunhofer Institute for Solar Energy Systems - http://www.ise.fraunhofer.de/welcome-to-the-web-pages-of-the-fraunhofer-institute-for-solar-energy-systems?set_language=en&cl=en

North America

NREL – National Renewable Energy Laboratory - http://www.nrel.gov/