Osun State

Rooftop solar in Isokan, Osun: what the roofs are worth

Isokan has 31,337 buildings with a viable rooftop and 698 MWp of roof capacity. 29% run a generator, and together they spend ₦13.6bn a year on energy.

Viable buildings

31,337

Usable roof area

3.1 km²

698 MWp roof capacity

Energy spend

₦13.6bn/yr

10 GWh/yr burned on generators

Median payback

4.4 yr

Median IRR 25% (cash saved)

The savings bracket for Isokan

Approach B

Cash saved

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

Current energy spend₦13.6bn/yr

Year-one cash saved₦11.9bn

Lifetime cash saved₦663bn

NPV₦91.9bn

Median IRR25%

Median payback4.4 yr

Unlocked energy14.1 GWh/yr

Approach A

Energy value (upper bracket)

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

Installed capacity73.7 MWp

Capex₦75.4bn

Year-one energy value₦63.8bn

Lifetime energy value₦2.91tn

NPV₦493bn

Median IRR75%

Median payback1.4 yr

Three ways to size Isokan'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: 73.7 MWp
Capital cost: ₦75.4bn
Year 1 savings: ₦63.8bn/yr
NPV: ₦493bn
Median IRR: 75%
Median payback: 1.4 yr

The odds a rooftop in Isokan pays back quickly

Of the 30,840 buildings in Isokan with a modelled payback, 70.4% pay back inside five years and 28.1% inside three.

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How much of Isokan's demand actually gets met

Buildings in Isokan consume 27.8 GWh/yr but want 41.9 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 Isokan

Loading band economics…

How many rooftops in Isokan 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 30,840 buildings with a modelled result out of 31,337 in Isokan. 25,481 clear a positive NPV.

Payback

Under 3 years8,666 (28%)

Under 5 years21,702 (70%)

Under 7 years25,444 (83%)

Under 10 years27,355 (89%)

Return (IRR)

Above 10%27,130 (87%)

Above 15%25,481 (81%)

Above 20%22,529 (72%)

Above 25%15,242 (49%)

CO₂ avoided

25.1 kt/yr

Fuel avoided

4.99 million litres/yr

Energy unlocked

14.1 GWh/yr

Demand that is suppressed today

People served

344k

What hardware costs right now

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

Solar panels

₦250

₦/W

Inverters

₦127,419

₦/kVA

Batteries

₦177,500

₦/kWh

Full price tracker Size a home system Size a business system

Building mix in Isokan

Electricity billing band

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
D	14,420	5,278	₦7.76bn	₦6.43bn	25%	4.4 yr
C	12,581	3,404	₦3.45bn	₦3.44bn	25%	4.4 yr
E	4,327	401	₦2.36bn	₦2.02bn	25%	4.4 yr
B	9	2	₦2.94m	₦2.94m	25%	4.4 yr

Load profile

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Residential	30,006	8,339	₦10.8bn	₦9.2bn	25%	4.4 yr
Industrial	480	233	₦398m	₦395m	37%	2.9 yr
Commercial General	457	249	₦959m	₦959m	35%	3.1 yr
Anchor	270	218	₦1.43bn	₦1.32bn	51%	2.1 yr
Commercial Retail	110	38	₦12.4m	₦12.4m	33%	3.4 yr
Filling Station	11	5	₦6.53m	₦6.46m	33%	3.1 yr
Worship	3	3	₦892k	₦892k	53%	1.9 yr

Roof size band

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
100 250m2	12,514	3,821	₦5.39bn	₦5.25bn	25%	4.4 yr
Under 30m2	6,752	1,785	₦201m	₦197m	13%	7.6 yr
50 100m2	5,627	1,245	₦1.7bn	₦1.12bn	25%	4.4 yr
30 50m2	3,385	846	₦242m	₦227m	19%	5.6 yr
250 1000m2	3,037	1,378	₦5.67bn	₦4.73bn	25%	4.4 yr
Over 1000m2	22	10	₦372m	₦372m	31%	3.1 yr

Settlement type

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Urban Centre	22,474	7,931	₦7.1bn	₦7.07bn	25%	4.4 yr
Unclassified	5,755	436	₦2.78bn	₦2.04bn	25%	4.4 yr
Urban	2,388	548	₦2.08bn	₦1.44bn	25%	4.4 yr
Dense Urban	471	117	₦341m	₦341m	25%	4.4 yr
Rural	249	53	₦1.28bn	₦1bn	25%	4.4 yr

Building type

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Residential Formal	14,650	3,785	₦2.14bn	₦2.14bn	25%	4.4 yr
Residential	4,134	1,801	₦6.27bn	₦5.3bn	25%	4.1 yr
Residential Small	4,014	1,124	₦1.71bn	₦1.1bn	25%	4.4 yr
Shed	3,288	484	₦66.4m	₦66.4m	7%	14.4 yr
Apartment	2,133	466	₦286m	₦286m	25%	4.4 yr
Duplex	1,092	222	₦134m	₦134m	25%	4.4 yr
Residential Informal	641	456	₦168m	₦168m	39%	2.6 yr
Institutional	353	209	₦702m	₦702m	41%	2.6 yr
Industrial Site	222	103	₦219m	₦218m	37%	2.9 yr
Industrial	127	64	₦119m	₦117m	37%	2.9 yr
Kiosk Shop	110	38	₦12.4m	₦12.4m	33%	3.4 yr
Commercial Corridor	104	34	₦248m	₦248m	33%	3.1 yr

Land use

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)
(Unset)	31,337	9,085	₦13.6bn	₦11.9bn

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	30,376	8,546	₦11.4bn	₦9.8bn	25%	4.4 yr
Enterprise	750	451	₦1.83bn	₦1.72bn	47%	2.4 yr
SME High	211	88	₦377m	₦377m	35%	3.1 yr

Demand tier

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)
4.0	16,602	4,367	₦4.05bn	₦4.02bn
3.0	7,486	3,187	₦7.7bn	₦6.6bn
0.0	3,343	485	₦68.1m	₦68.1m
2.0	2,793	789	₦1.35bn	₦811m
1.0	990	208	₦218m	₦203m
5.0	108	43	₦133m	₦133m
6.0	15	6	₦60.6m	₦60.6m