Taraba State

Rooftop solar in Donga, Taraba: what the roofs are worth

Donga has 120,961 buildings with a viable rooftop and 737 MWp of roof capacity. 4% run a generator, and together they spend ₦7.53bn a year on energy.

Viable buildings

120,961

Usable roof area

3.37 km²

737 MWp roof capacity

Energy spend

₦7.53bn/yr

5.71 GWh/yr burned on generators

Median payback

16.6 yr

Median IRR 5% (cash saved)

The savings bracket for Donga

Approach B

Cash saved

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

Current energy spend₦7.53bn/yr

Year-one cash saved₦7.35bn

Lifetime cash saved₦413bn

NPV₦56.7bn

Median IRR5%

Median payback16.6 yr

Unlocked energy10.1 GWh/yr

Approach A

Energy value (upper bracket)

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

Installed capacity66.5 MWp

Capex₦70.5bn

Year-one energy value₦66.1bn

Lifetime energy value₦3.13tn

NPV₦532bn

Median IRR93%

Median payback1.1 yr

Three ways to size Donga'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: 66.5 MWp
Capital cost: ₦70.5bn
Year 1 savings: ₦66.1bn/yr
NPV: ₦532bn
Median IRR: 93%
Median payback: 1.1 yr

The odds a rooftop in Donga pays back quickly

Of the 116,675 buildings in Donga with a modelled payback, 17.6% pay back inside five years and 4.5% inside three.

Create a free account

How much of Donga's demand actually gets met

Buildings in Donga consume 15.8 GWh/yr but want 25.9 GWh/yr. The 39% they cannot buy is suppressed demand — load that appears the moment supply is reliable.

Create a free account

Electricity billing bands in Donga

Loading band economics…

How many rooftops in Donga 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 116,675 buildings with a modelled result out of 120,961 in Donga. 28,378 clear a positive NPV.

Payback

Under 3 years5,234 (4%)

Under 5 years20,581 (18%)

Under 7 years28,390 (24%)

Under 10 years34,891 (30%)

Return (IRR)

Above 10%33,508 (28%)

Above 15%28,378 (23%)

Above 20%22,375 (18%)

Above 25%17,857 (15%)

CO₂ avoided

16 kt/yr

Fuel avoided

3.07 million litres/yr

Energy unlocked

10.1 GWh/yr

Demand that is suppressed today

People served

243k

What hardware costs right now

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

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 Donga

Electricity billing band

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
D	48,256	1,582	₦1.93bn	₦1.82bn	5%	17.4 yr
E	39,637	1,194	₦1.64bn	₦1.64bn	5%	17.6 yr
C	20,286	1,063	₦1.71bn	₦1.69bn	7%	14.4 yr
B	12,782	1,271	₦2.24bn	₦2.21bn	19%	5.4 yr

Load profile

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Residential	116,986	3,455	₦5.43bn	₦5.26bn	5%	16.9 yr
Commercial Retail	1,792	494	₦95.8m	₦95.8m	35%	3.1 yr
Commercial General	1,485	641	₦1.04bn	₦1.04bn	35%	3.1 yr
Anchor	402	295	₦859m	₦859m	57%	1.9 yr
Worship	235	189	₦61.5m	₦61.5m	55%	1.9 yr
Industrial	56	34	₦35.7m	₦35.7m	53%	1.9 yr
Filling Station	5	2	₦2.75m	₦2.75m	35%	3.1 yr

Roof size band

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Under 30m2	80,973	1,679	₦277m	₦277m	3%	18.1 yr
30 50m2	16,112	847	₦270m	₦270m	9%	13.4 yr
50 100m2	15,549	1,156	₦1.04bn	₦1.03bn	23%	4.6 yr
100 250m2	7,265	1,086	₦2.94bn	₦2.78bn	27%	3.9 yr
250 1000m2	1,038	332	₦2.46bn	₦2.45bn	29%	3.9 yr
Over 1000m2	24	10	₦543m	₦543m	31%	2.9 yr

Settlement type

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Unclassified	71,670	1,337	₦2.45bn	₦2.42bn	5%	18.1 yr
Dense Urban	16,959	1,415	₦2.76bn	₦2.62bn	17%	6.1 yr
Rural	16,458	936	₦561m	₦561m	7%	15.4 yr
Urban	15,874	1,422	₦1.76bn	₦1.76bn	11%	8.6 yr

Building type

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)	Median IRR	Median payback
Shed	86,766	1,428	₦258m	₦258m	5%	17.9 yr
Residential Small	17,075	1,089	₦1.04bn	₦1.03bn	23%	4.6 yr
Residential	7,610	938	₦4.07bn	₦3.91bn	27%	3.9 yr
Residential Formal	2,994	0	₦11.6m	₦11.6m	5%	13.4 yr
Residential Informal	2,505	0	₦47.7m	₦47.7m	17%	6.1 yr
Kiosk Shop	1,792	494	₦95.8m	₦95.8m	35%	3.1 yr
Commercial	676	166	₦440m	₦440m	35%	3.1 yr
Commercial Corridor	410	139	₦347m	₦347m	35%	3.1 yr
Institutional	323	246	₦632m	₦632m	51%	2.1 yr
Market	163	160	₦17m	₦17m	59%	1.9 yr
Educational Facility	158	126	₦160m	₦160m	75%	1.4 yr
School	101	77	₦79.2m	₦79.2m	75%	1.4 yr

Land use

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)
(Unset)	120,924	5,110	₦7.53bn	₦7.35bn
Farmland	37	0	₦419k	₦419k

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	119,430	4,482	₦5.85bn	₦5.67bn	5%	16.9 yr
SME High	1,091	307	₦790m	₦790m	35%	3.1 yr
Enterprise	440	321	₦890m	₦890m	57%	1.9 yr

Demand tier

Segment	Buildings	With generator	Spend ₦/yr	Cash saved yr 1 (B)
0.0	86,809	1,451	₦259m	₦259m
3.0	13,471	1,482	₦4.98bn	₦4.82bn
2.0	12,083	1,257	₦1.21bn	₦1.21bn
1.0	4,415	684	₦294m	₦285m
4.0	3,546	66	₦268m	₦268m
5.0	604	153	₦324m	₦324m
6.0	33	17	₦186m	₦186m