The article shows various GIS (Geographic Information Systems) solutions help solar siting. One is Google Earth or Google Maps (the article blurs the difference), to look at satellite imagery from Google Earh or Google Maps: the article blurs the difference, and also doesn't explain why Google is better than Yahoo. Photos from space could suggest the optimal location on a site for solar panels, free from building or tree shading.
The article also says that SolarCity uses Google Earth to measure roof size.
Finally, there is a new solar map of the Western Hemisphere from 3Tier of Seattle. The FirstLook map, browsable online by latitude/longitude or zipcode, uses 11 years of NOAA satellite data to estimate average incident solar radiation at a given address. The map presents the data as a color-coded overlay onto the Google Maps service.
The map is free to browse. From it, I concluded that the average daily incipient radiation at my San Jose home is about 5 kWh per square meter — above average for the US but typical for the Western US.
3Tier is giving away aggregate data useful for consumers, but wants to sell more sophisticated data to solar professionals. It provides free to consumers global horizontal irradiance, which includes both direct and diffuse incident light. It sells the direct normal irradiation, which is most useful for commercial, sun-tracking systems. Among the data it sells is the breakdown of radiation by month and time of day.
Both the analysis and installation companies right now are enjoying a boom period that looks to continue for many years. Solar hot water installers enjoyed a boom in the 1970s and 1980s, but then it went bust after tax credits expired and all the most likely customers had been serviced. Right now, I can’t see how to predict whether the residential installation boom in the US will last 2 years or 20.