For many small and medium-sized enterprises in Nigeria and across Africa, power is not just a utility bill. It is often one of the largest operational expenses, directly impacting net profit margins and cash flow survival.
Yet, most business owners fail to calculate true energy cost running their operations. They rely solely on monthly fuel receipts and electricity bills, ignoring substantial hidden factors like equipment depreciation, maintenance cycles, and the productivity losses of sudden power cuts.
Understanding these real numbers is critical for making strategic decisions about pricing, capital allocation, and transitioning to alternative energy sources like solar power.
Mapping your daily power consumption
Before calculating financial costs, you must understand your physical energy footprint. This begins by list-building every appliance, machine, and light bulb in your facility alongside their power ratings in watts or kilowatts.
To find the daily kilowatt-hour consumption of an appliance, multiply its wattage by the number of hours it runs each day, then divide by 1,000. For example, three 150-watt office desktop computers running for 8 hours consume 3.6 kWh daily.
Aggregating these numbers across your workspace provides your total daily baseline demand. This baseline prevents you from over-purchasing generator capacity or under-sizing an inverter system.
The hidden components of generator expenses
Relying on a petrol or diesel generator involves costs that extend far beyond the fuel pump. A true financial assessment must incorporate regular maintenance and asset depreciation.
Consider a standard 20 kVA diesel generator running at a typical 75% load of 15 kW. It consumes approximately 4 litres of diesel per hour of operation.
At a diesel price of N1,250 per litre, the direct fuel cost is N5,000 per hour. However, the machine requires oil, filter, and belt services roughly every 250 run hours, costing about N60,000 per service, which adds N240 per hour.
Additionally, a quality generator costing N10 million has an estimated useful lifespan of 20,000 run hours. Dividing the purchase price by the lifespan yields a depreciation cost of N500 per hour.
Adding fuel, servicing, and depreciation brings the true running cost to N5,740 per hour. Dividing this by the 15 kW load reveals a real cost of N382.67 per kWh, significantly higher than even the premium Band A grid tariffs.
Amortising solar and battery alternatives
Transitioning to solar power requires a high upfront capital expenditure, but it drastically reduces recurring operational expenses over time. To compare solar with generators fairly, you must amortise the initial cost over the system’s useful life.
Suppose your business installs an 8 kW solar hybrid system with a 15 kWh lithium battery for N6 million. If you amortise this capital outlay over a conservative lifespan of five years, the monthly capital cost is N100,000.
Assuming the solar system generates an average of 20 kWh per day, it delivers roughly 600 kWh of electricity each month. This results in an amortised cost of approximately N166.67 per kWh, with near-zero ongoing fuel costs.
This comparative math demonstrates that solar energy often delivers power at less than half the hourly cost of diesel self-generation, once depreciation is properly factored into the generator equation.
Establishing a single comparative metric
To manage your energy budget effectively, convert all power sources into a single metric: cost per kilowatt-hour. This metric allows you to compare grid power, diesel generation, petrol generation, and solar on an identical basis.
| Power Source | Estimated Cost per kWh (NGN) | Primary Cost Driver |
|---|---|---|
| Grid Power (Band A) | 209.50 | Regulatory Tariffs |
| Solar Hybrid (Amortised) | 166.67 | Upfront Capital Expenditure |
| Diesel Generator (20 kVA) | 382.67 | Fuel Price and Depreciation |
SME owners should immediately begin tracking generator run hours using a physical logbook or digital hour-meter. Compare these hours against weekly fuel purchases to identify fuel theft, engine inefficiency, or wasteful operational run times.
