A quick summary. Tap any i or dotted figure on the map
for how it's worked out; the full technical detail is in
ARCHITECTURE.md.
Solar installs
Region figures — installs, capacity, homes/business and % of connections — are EMI's own published numbers (the Electricity Authority), exact.
Streets come from EMI's street-level file, matched to OpenStreetMap roads. Streets with three or fewer installs are published as “3 or less” for privacy, shown here as 1–3.
Town and district counts (marked “~”) are added up from those streets, counting each “3 or less” street at its region's measured average, so each region's streets add up to EMI's exact total.
Town and district % (marked “est”) is modelled: 2023 Census dwellings projected forward, scaled up to all connections using the region's mix. EMI publishes no connection total that fine.
Batteries are EMI figures, published by region only — towns show their region's rate.
Farms (marked “~”) are our estimate, since EMI publishes no farm split: every road outside towns with business solar is judged on the land along it (Manaaki Whenua land cover) and the other businesses on it (OpenStreetMap). Solar on farmhouses counts as homes, so farms with any solar are probably more.
Solar farms — grid-scale power stations rather than rooftops — are shown separately and left out of the farm, rural business and town figures.
Electric vehicles
Counts by district from NZTA's Motor Vehicle Register, not modelled. “% of the fleet” is electric vehicles as a share of all registered vehicles in that district, excluding trailers, caravans and forklifts.
Vehicle Details lists the most common electric and fossil-fuelled models (petrol, diesel, hybrid, plug-in hybrid) by region and district.
Keeping it current
Refreshes automatically every week. EMI and NZTA publish on their own schedules (EMI's street data currently updates about weekly, NZTA's register about monthly); “Updated” shows each source's own release date.