Solar glossary
Grid availability: what it means and why it matters
The share of hours the grid is actually delivering power to a location, derived from night-time lights.
Why it matters in Nigeria
It decides how much of a building's energy comes from a generator, and therefore how expensive its energy really is.
How PureWatts measures it
Grid avail frac
n_grid_avail_frac
Count of buildings in the group with a NON-NULL value for this metric — a COVERAGE denominator, not a copy of n_buildings. It equals n_buildings when every building has the metric (band_*, which is joined for all cells) and falls below it where the metric is undefined (payback for buildings that never pay back, rwi where the surface has no cell). Divide by n_buildings to get coverage; use it as the denominator when re-weighting the mean/median beside it. Grid availability, from the NTL proxy.
Count of buildings in the group with a NON-NULL value for this metric — a COVERAGE denominator, not a copy of n_buildings. It equals n_buildings when every building has the metric (band_*, which is joined for all cells) and falls below it where the metric is undefined (payback for buildings that never pay back, rwi where the surface has no cell). Divide by n_buildings to get coverage; use it as the denominator when re-weighting the mean/median beside it.
Median Grid avail frac
med_grid_avail_frac
Median over the buildings in the group. Medians DO NOT COMBINE — never average these across groups; re-derive from the histograms instead. Grid availability, from the NTL proxy.
Median over the buildings in the group. Medians DO NOT COMBINE — never average these across groups; re-derive from the histograms instead.
See these numbers for your area
Every state and local government area page reports grid availability for its own rooftops. Browse the Nigeria rooftop solar data.