Oyo State

Rooftop solar in Ona Ara, Oyo: what the roofs are worth

Ona Ara has 129,832 buildings with a viable rooftop and 2.79 GWp of roof capacity. 31% run a generator, and together they spend ₦40.3bn a year on energy.

Viable buildings

129,832

Usable roof area

12.4 km²

2.79 GWp roof capacity

Energy spend

₦40.3bn/yr

28.9 GWh/yr burned on generators

Median payback

4.4 yr

Median IRR 25% (cash saved)

The savings bracket for Ona Ara

Approach B

Cash saved

What these buildings stop paying — merit order, capped at current spend.

Current energy spend₦40.3bn/yr

Year-one cash saved₦35.9bn

Lifetime cash saved₦1.96tn

NPV₦272bn

Median IRR25%

Median payback4.4 yr

Unlocked energy38.9 GWh/yr

Approach A

Energy value (upper bracket)

What the energy is worth if full latent demand were met. Not cash saved.

Installed capacity161 MWp

Capex₦171bn

Year-one energy value₦118bn

Lifetime energy value₦5.58tn

NPV₦901bn

Median IRR67%

Median payback1.6 yr

Three ways to size Ona Ara's rooftops

Solar + battery. The default headline scenario, and the one the SEO fact base quotes. Prices the energy a full solar+storage system would deliver.

Baseline: mixed

Counterfactual: grid when available, generator otherwise, weighted by the NTL-derived grid availability. The realistic case, and what the headline numbers use. Always falls between grid and genset by construction.

Read with care: 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.

System size: 161 MWp
Capital cost: ₦171bn
Year 1 savings: ₦118bn/yr
NPV: ₦901bn
Median IRR: 67%
Median payback: 1.6 yr

The odds a rooftop in Ona Ara pays back quickly

Of the 128,780 buildings in Ona Ara with a modelled payback, 71.8% pay back inside five years and 20.7% inside three.

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How much of Ona Ara's demand actually gets met

Buildings in Ona Ara consume 75.7 GWh/yr but want 115 GWh/yr. The 34% they cannot buy is suppressed demand — load that appears the moment supply is reliable.

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Electricity billing bands in Ona Ara

Loading band economics…

How many rooftops in Ona Ara actually pay

Counted building by building on the cash-saved basis (merit-order sized, valued against what the building spends today), not read off an average. Shares are of the 128,780 buildings with a modelled result out of 129,832 in Ona Ara. 111,778 clear a positive NPV.

Payback

Under 3 years26,662 (21%)

Under 5 years92,510 (72%)

Under 7 years111,620 (87%)

Under 10 years120,559 (94%)

Return (IRR)

Above 10%119,503 (92%)

Above 15%111,778 (86%)

Above 20%98,163 (76%)

Above 25%56,654 (44%)

CO₂ avoided

74.7 kt/yr

Fuel avoided

16.4 million litres/yr

Energy unlocked

38.9 GWh/yr

Demand that is suppressed today

People served

384k

What hardware costs right now

Median advertised rates from our Nigerian market tracker — the same prices used to cost a system in Ona Ara.

Solar panels

₦250

₦/W

Inverters

₦127,419

₦/kVA

Batteries

₦177,500

₦/kWh

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Building mix in Ona Ara

Electricity billing band

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
C	81,428	24,351	₦17.1bn	₦17bn	25%	4.4 yr
B	26,903	10,426	₦8.28bn	₦8.28bn	25%	4.4 yr
D	16,620	4,181	₦3.96bn	₦3.54bn	25%	4.4 yr
E	4,881	650	₦11bn	₦7.1bn	25%	4.4 yr

Load profile

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Residential	128,011	38,672	₦36.4bn	₦32.3bn	25%	4.4 yr
Industrial	648	348	₦983m	₦977m	37%	2.9 yr
Anchor	507	259	₦1.93bn	₦1.64bn	41%	2.6 yr
Commercial General	461	235	₦880m	₦880m	33%	3.4 yr
Worship	144	73	₦109m	₦109m	33%	3.1 yr
Filling Station	44	16	₦33.7m	₦33.7m	33%	3.1 yr
Hospitality	7	4	₦15.9m	₦15.9m	33%	3.1 yr
Mall Retail	5	0	₦14m	₦14m	35%	3.1 yr
Commercial Retail	4	0	₦321k	₦321k	33%	3.4 yr
Automotive	1	1	₦4.24m	₦4.24m	43%	2.6 yr

Roof size band

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
100 250m2	56,089	17,202	₦18.5bn	₦17.6bn	25%	4.4 yr
Under 30m2	26,242	7,837	₦602m	₦595m	15%	6.6 yr
50 100m2	24,422	7,066	₦2.31bn	₦2.28bn	25%	4.6 yr
30 50m2	12,843	3,764	₦546m	₦546m	21%	5.4 yr
250 1000m2	10,197	3,718	₦17.3bn	₦14.1bn	25%	4.4 yr
Over 1000m2	39	21	₦1.06bn	₦818m	45%	2.4 yr

Settlement type

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Urban Centre	98,921	32,876	₦23bn	₦22.9bn	25%	4.4 yr
Urban	20,915	4,783	₦3.87bn	₦3.87bn	25%	4.4 yr
Unclassified	9,016	1,382	₦5.68bn	₦4.66bn	23%	4.6 yr
Rural	980	567	₦7.78bn	₦4.52bn	69%	1.6 yr

Building type

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Residential Formal	63,596	20,283	₦11.7bn	₦11.7bn	25%	4.4 yr
Residential Small	16,217	4,420	₦1.93bn	₦1.89bn	25%	4.6 yr
Residential	14,444	4,161	₦18.1bn	₦14bn	25%	4.4 yr
Shed	11,728	3,316	₦312m	₦312m	17%	6.1 yr
Apartment	9,554	2,203	₦829m	₦829m	25%	4.4 yr
Residential Informal	8,530	3,034	₦3.06bn	₦3.06bn	25%	4.4 yr
Duplex	3,837	1,221	₦431m	₦431m	25%	4.4 yr
Institutional	622	333	₦1.78bn	₦1.54bn	33%	3.4 yr
Industrial Site	323	172	₦558m	₦554m	39%	2.9 yr
Industrial	161	88	₦317m	₦315m	37%	2.9 yr
Educational Facility	147	79	₦254m	₦254m	47%	2.4 yr
School	139	69	₦117m	₦117m	43%	2.4 yr

Land use

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)
(Unset)	129,826	39,608	₦40.3bn	₦35.9bn
Farmland	5	0	₦92.1k	₦92.1k
Farmyard	1	0	₦10.1k	₦10.1k

Not published for this cube: Median IRR, Median payback.

Lead segment

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Standard	128,624	38,983	₦37.4bn	₦33.3bn	25%	4.4 yr
Enterprise	1,152	607	₦2.91bn	₦2.61bn	41%	2.6 yr
SME High	56	18	₦57.4m	₦57.4m	33%	3.1 yr

Demand tier

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)
4.0	69,075	20,796	₦14.4bn	₦14.4bn
3.0	34,320	11,245	₦23.1bn	₦18.8bn
2.0	12,557	3,869	₦2.18bn	₦1.98bn
0.0	10,851	2,715	₦247m	₦247m
1.0	2,977	959	₦207m	₦204m
5.0	45	22	₦179m	₦179m
6.0	7	2	₦27.7m	₦27.7m