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Map a calibration area with iD

iD is OpenStreetMap's editor in the browser: nothing to install, and the atlas opens it on your area with the boundary already drawn. It is the easiest way to map your first area, especially a sparse candidate with a few hundred buildings. For dense areas with thousands of buildings, JOSM is faster.

You need a free OpenStreetMap account. Log in on openstreetmap.org before you start, so iD opens ready to save.

1. Open the area

On a country's atlas, click a candidate (hollow diamond; the star marks the one to map first) or a finished area (filled diamond) and press Open in iD. A new tab opens iD:

  • centred on the area, at zoom 16;
  • with the area's boundary drawn as a dashed overlay. It is iD's Custom Map Data layer (Map Data panel, key U), which iD never uploads, so you cannot add the box to OpenStreetMap by accident;
  • on Esri World Imagery, the layer whose capture date the atlas checked;
  • with the changeset comment and the hashtags #tracethesun #earthpv #earthpv-calibration filled in for when you save.

Screenshot needed · save as docs/assets/figures/contribute-id-boundary.png

Show: iD right after pressing Open in iD on a candidate, at about zoom 17 over Esri World Imagery. The dashed boundary of the area crosses the view, with a few houses on either side, and the Map Data panel (key U) is open on the right with Custom Map Data ticked. Ideally one or two panels are already traced inside the line.

The boundary is the whole job: every panel inside the line, nothing required outside it. A panel that straddles the line is still worth mapping; whether it counts is decided later from its centre.

2. Check the imagery date

Press Ctrl+Shift+B (macOS: Cmd+Shift+B) to open the background info panel. For Esri World Imagery it shows the capture date of the imagery under the centre of the screen. Compare it with the date in the atlas popup.

If the imagery is more than about a year older than the date in the popup, or the box sits on nothing you could map (open desert, water, a quarry), stop here and report it as not mappable. That is a useful result, not a failure.

Screenshot needed · save as docs/assets/figures/contribute-id-imagery-date.png

Show: the same area in iD with the Background panel (key B) open on the right, listing the available imagery (Esri World Imagery selected, Bing and Mapbox visible), and the background info panel at the bottom (Ctrl+Shift+B) showing Esri's capture date.

3. Map every panel

Every installation inside the line, on roofs and on the ground, whatever kind of area it is: both of the project's detectors learn from every area.

  1. Zoom in to 18 or 19, so a single panel group is clearly visible.
  2. Press 3 (the Area tool) and click around the panels only, never the whole roof. Close the shape by clicking the first point again.
  3. In the preset list, type solar and pick:
    • Rooftop Solar Panel for panels on a building;
    • Solar Panel for panels on the ground (fields, yards, pump frames).
  4. Press Q to square the corners, if the shape is a rectangle.

One area per contiguous group of panels; two separate groups on one roof are two areas. For a tiny installation where tracing is hopeless (under about 4 m2), a point with the same preset is fine.

Screenshot needed · save as docs/assets/figures/contribute-id-preset.png

Show: one traced rooftop panel group selected in iD, with the preset search on the left after typing solar, showing Rooftop Solar Panel at the top of the results and Solar Panel below it.

The presets set the tags the calibration reads:

power=generator
generator:source=solar
generator:method=photovoltaic
generator:type=solar_photovoltaic_panel
generator:output:electricity=yes
location=roof                  (Rooftop Solar Panel only)

Not solar: water heaters (tubes or a round tank), skylights, blue-painted roofs. If you really cannot tell at full zoom, map it and add the tag fixme=possible solar (in the tag editor's text view) rather than guessing either way.

4. Sweep the whole box

Work through the box in strips, street by street, instead of jumping to what catches your eye. Then switch the imagery (key B) and sweep again: Esri World Imagery, Bing, Mapbox Satellite and any regional layer iD lists for the area. A panel invisible on one layer is often obvious on the next, because the layers differ in date, sun angle and sharpness. Mapping against a single layer is the most common reason a "complete" area is not.

5. Save

Press I to check iD's issues panel, then save (Ctrl+S). The comment and hashtags are already filled in; iD records the imagery you used on its own. Save every hour or so rather than once at the end: smaller changesets are easier for others to review.

Screenshot needed · save as docs/assets/figures/contribute-id-save.png

Show: iD's save panel before uploading, with the prefilled changeset comment (Map rooftop and ground-mounted solar PV in ... (earthpv calibration area)) and the hashtags #tracethesun #earthpv #earthpv-calibration, and the number of changes visible.

Then report your progress: finished, partly done, or not mappable.

Your own proposed area

A box from the atlas's Propose a calibration area button has no published file yet, so Open in iD only opens at its location. Press GeoJSON in the popup to download the box, then drag the file onto the iD map: it appears as the same never-uploaded overlay. iD cannot draw and save a boundary of your own; for that, see Draw your own area, which uses JOSM.