Weather Underground (AKA: Wunderground) is the world's first online weather service provider founded by IBM in 1995, providing meteorological data solutions to many of the world's leading media companies and millions of worldwide users through its website and mobile applications. We can use it to query the global and local weather data anytime and anywhere to learn the latest weather forecast information.

Meteorological data includes the conventional ground meteorological data and the solar energy resource radiation data. In the actual development of photovoltaic power generation projects, most investors use the radiation data from relevant meteorological databases to calculate the photovoltaic power generating capacity. At present, NASA and Meteonorm are the main sources of solar energy radiation data for early site selection and revenue estimation of photovoltaic power stations. They are the industry standard of solar resource query software in the photovoltaic industry.