Ask a facility manager what an hour of generator runtime costs and you will usually get a fuel number: litres burned times pump price. At ₦1,100 per litre and 40 litres an hour on a 250kVA set, that is ₦44,000 — painful, but apparently survivable. The problem is that fuel is barely half the bill.
The four lines your logbook skips
Start with maintenance. A 250kVA diesel engine wants oil, filters and attention every 250 running hours. Priced honestly — parts, technician callouts, and the coolant nobody budgets — that adds roughly ₦180 per kWh generated. Then depreciation: a ₦28M generator run 5,000 hours a year is consuming its own ₦2.8M of value annually before overhaul reserves. Third, the overhaul cliff itself: top-end work at 10,000 hours, major rebuild at 20,000, each costing 30–60% of a new machine.
The fourth line is the one boards feel but never itemise: downtime. When the set trips on a Friday evening, you are not saving the diesel — you are paying for it in spoiled inventory, missed transactions and staff overtime. Across the industrial clients we audit, unplanned generator downtime costs between ₦3,000 and ₦11,000 per kVA per year.
What the audit usually finds
When we instrument a site for two weeks — actual load curves, not nameplate guesses — the honest cost of diesel power lands between ₦420 and ₦560 per kWh. Band A grid power, when it shows, costs ₦225. A properly sized solar-hybrid system, amortised over its warranted life, delivers at ₦140–₦190 per kWh.
That spread is why our proposals lead with a payback period, not a sustainability slide. At Zenith Agro's rice complex, 2.4MW of solar with 4.8MWh of storage cut generator runtime from 22 hours a day to 90 minutes. Diesel spend fell 81%. The system cleared its capital cost in 41 months — faster than the client's own hurdle rate for plant investment.
The decision, reframed
None of this requires believing anything about the climate. It requires believing your own meter data. Run the two-week audit, price the diesel hour honestly, and the question stops being whether you can afford solar-hybrid. It becomes how much longer you can afford the logbook fiction.
Our estimator on this site uses the same zone irradiance values and tariff assumptions we defend in audits. Start there; argue with the assumptions; then let a site survey settle it.
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