Solar glossary
Energy independence: what it means and why it matters
The share of a building's energy that the solar and battery system supplies on its own.
Why it matters in Nigeria
It answers the question people actually ask: how much of the time can I stop caring about the grid and the generator?
How PureWatts measures it
Median Energy independence (Solar + battery)
med_sc2_energy_independence_pct
Median over the buildings in the group. Medians DO NOT COMBINE — never average these across groups; re-derive from the histograms instead. Share of demand met without the grid.
Solar + battery: PV sized to cover FULL demand including round-trip losses: kwp = min(demand x (daylight + (1-daylight)/0.90) x 1.10 / net_yield, pv_max_kwp); battery = night demand / (0.80 DoD x sqrt(0.90)), capped at 2.0x PV kWp
Sized to LATENT demand — the energy the building would use if it could. Against a cash baseline that only reflects today's spend this looks oversized; that is what sc3 exists to fix.
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 energy independence for its own rooftops. Browse the Nigeria rooftop solar data.
Related terms
How these numbers are produced
Approach A — energy value (upper bracket)
Sizes the system to the building's full latent demand and values that energy at the mixed grid/generator tariff. It answers what the energy is worth — not what anyone currently pays.
Approach B — cash saved (lower bracket)
Sizes the system to demand that is actually served today, values it by merit order (solar displaces generator kWh first) and caps it at current spend. It answers what a building stops paying.
Cohort: Viable rooftops (≥0.6 kWp potential).
- Demand is modelled latent demand, not metered consumption.
- Fuel is priced at ₦1,800/litre (operator-set). NBS reported ₦3,277/litre for May 2026 — on that basis every naira figure here is roughly 1.8× understated.
- Generator ownership is a model output, not a survey result: it follows from the grid-availability scale and the 25% demand-suppression assumption.
- Approach A prices energy nobody currently buys. Its savings must never be read as cash saved.
- Demand is MODELLED LATENT demand, not metered consumption.
- Generator ownership is model output, not survey.
- Medians do not combine across groups — re-derive from the histograms.
- Per-building files are float32 with 4 significant figures; cast to float64 before summing, because polars keeps Float32 sums in Float32.
- Null scenario fields mean the roof cannot host 0.6 kWp, not zero savings.
- `genset` was previously named `diesel` and now uses the segment's real fuel.
- Ordering holds by construction: grid savings < mixed < genset.