GIS for renewable-energy developers: the essentials

A Geographic Information System (GIS) is software for storing, analysing and drawing data that has a location. For a wind or solar developer that is most of the data that matters: parcels, turbines, roads, substations, setbacks, wind resource, terrain. Most project teams use GIS every day without calling it that, in Google Earth, in a spreadsheet of coordinates, or in a CAD layout. Knowing a few core ideas makes all of those tools work better together.

Layers

A GIS project is a stack of layers, each holding one kind of thing: a layer of turbine points, a layer of parcel polygons, a layer of road lines, a satellite image. Layers are drawn on top of each other, switched on and off, and styled independently. Keeping one kind of feature per layer is the single habit that makes later analysis easy.

Vector and raster

Vector data is made of points, lines and polygons with coordinates: a turbine is a point, a cable route is a line, a parcel is a polygon. Each feature carries attributes, such as a turbine ID, rotor diameter or survey number.

Raster data is a grid of cells with a value in each: elevation, slope, wind speed at hub height, a satellite image. Rasters are how continuous quantities are stored.

Most project questions combine the two: which turbines (vector) sit on slopes above 15 degrees (raster)?

Coordinate reference systems

Every layer has a coordinate reference system (CRS) that says what its numbers mean. Two ingredients matter.

• The datum anchors the coordinates to the Earth. WGS84 is the default; older Indian data may be on Everest 1830. Mixing datums shifts things by hundreds of metres. See WGS84 vs Indian datums.
• The projection decides whether coordinates are angles (latitude and longitude) or metres on a flat plane (UTM eastings and northings). Distances and areas are only trustworthy in a projected system. See UTM zones in India.

A good GIS reprojects on the fly so layers line up, but analysis should be run in a projected CRS appropriate to the site.

The handful of operations that cover most project work

• Buffer. Draw a zone at a fixed distance around a feature: a 300 m setback around houses, a 5D circle around a turbine. Buffers turn rules into shapes.
• Intersect and clip. Find where two layers overlap: the parcels that fall inside the lease area, the turbines that fall inside a forest boundary.
• Point in polygon. Test whether a point lies inside a shape. Is this turbine inside the parcel we lease? Is it inside a competitor's solar boundary? See solar project boundaries.
• Distance and bearing. Measure between features on a sphere or in a projection. Spacing checks, cable lengths and wake corridors all reduce to distance and bearing.
• Convex hull. Wrap a set of points in the smallest polygon that contains them. Useful for turning a handful of corner coordinates into a site boundary.
• Join. Attach attributes from one table to features in another, for example rotor diameters from a turbine model table onto the turbine point layer.

Data formats you will meet

• CSV of coordinates: the universal exchange format. Fragile, because the CRS is not stored in the file.
• KML / KMZ: Google Earth's format. Good for sharing visual layouts with non-GIS users. See KML for wind and solar projects.
• Shapefile: the old GIS standard, actually a bundle of several files. Still everywhere.
• GeoJSON: a plain-text web format. Easy to generate, easy to read, always WGS84.
• GeoPackage: a single-file database that holds many layers with their CRS. The best choice for a project master file.
• DXF / DWG: CAD formats. Coordinates are usually UTM, and the datum often lives only in the title block.

Tools

QGIS is free, mature and does everything above. Google Earth Pro is free and unbeatable for quick visual checks and sharing. PostGIS turns a PostgreSQL database into a GIS engine and is what serious multi-project platforms run on. Spreadsheets remain the most common GIS in practice, and the source of most coordinate errors.

Where automation earns its keep

Nothing above is hard once. The difficulty is doing it correctly across hundreds of assets, several competitors, and every revision. That repetitive middle layer, checking spacing, testing boundaries and regenerating maps after each change, is what reneGIS automates for wind and solar projects. The free Coordinate Converter is the first of a set of small tools built on the same foundations.