This dataset was collected from Maryland Open Data. The dataset contains historical data on total grant amount awarded to different clean energy projects. The projects are grouped first by county and then by zipcode. They are aggregated into four different technology types and were colored accordingly: solar hot water, solar PV, geothermal and wind. The colors were chosen to represent the Maryland flag. Each box represents the total amount grant awarded for a certain technology in certain zip code.
There the projects were first divided into two groups where one had states with more expenditure on solar and the other had states with more expenditure in other technologies. They were then further categorized into solar and non-solar group.