Why "cost per kWh" is the only fair comparison
Comparing a generator's price to a solar system's price tells you almost nothing — they buy different things, over different lifespans. The honest comparison is cost per kilowatt-hour (kWh) delivered over the life of the system, including fuel and maintenance. That single number reframes the whole energy decision.
Diesel generation: KSh 40-55 per kWh
A modern diesel set burns roughly 0.25-0.30 litres of diesel per kWh at full load — and significantly more at light load, because the engine still has fixed friction and pumping losses to overcome. A set idling at 25% load can burn nearly twice as much fuel per useful kWh as the same set at 80%.
Cost per kWh ≈ (litres/hour × fuel price) ÷ kW delivered + maintenance share.
At 75% load on a 100 kVA set burning ~17 L/h, with diesel near KSh 165/litre: 17 × 165 ÷ 60 kW ≈ KSh 47/kWh before maintenance. That is the real cost of "just running the generator" as primary power — and it is why the cheapest kWh is the one you never generate on diesel.
Grid electricity: cheaper, but not always there
Commercial grid tariffs in Kenya sit well below diesel per kWh, which is why the grid should carry base load wherever it is reliable. The problem is reliability — outages and voltage events push businesses onto expensive diesel exactly when they can least afford the disruption.
Solar PV: KSh 8-15 per kWh over its life
A well-built solar system in Kenya's strong sun (5.0-6.0 peak sun hours across most of the country) delivers electricity at a levelised cost of roughly KSh 8-15 per kWh over 25 years. After payback, the marginal cost of a solar kWh is essentially zero.
Levelised cost ≈ total lifetime cost ÷ total lifetime kWh generated.
Indicative cost per kWh (lifetime levelised):
| Source | Approx. KSh/kWh |
|---|---|
| Solar PV (well designed) | 8-15 |
| Grid (commercial) | ~25-30 |
| Diesel generator | 40-55 |
The winning architecture: solar + generator hybrid
For most Kenyan businesses the answer is not one source but the right mix:
- Solar carries the cheap daytime base load.
- Grid supplements where reliable.
- A correctly sized generator becomes genuine backup for outages and night peaks — running far fewer hours, so its fuel bill collapses.
- Battery storage is added where the tariff and outage profile justify it.
This hybrid commonly cuts a site's diesel spend by 40-70% while keeping full resilience — the diesel you do not burn is the cheapest saving of all.
The bottom line
Treat your generator as insurance, not as your power station. Put your base load on the cheapest reliable kWh — increasingly your own solar — and size the generator to cover the gaps.
Send us your last 12 utility bills and your location and we will model your real cost per kWh and a solar-plus-generator option with payback — free. Call +254 768 860 665 or +254 782 914 717.