A single off-grid base station in West Africa burns 8,000 to 15,000 litres of diesel a year. Operators know the fuel number because it arrives as an invoice every month. What they usually do not have in one place is the ten-year total, which is the only number that decides whether a solar-hybrid system pays back. Here it is, built up line by line.
The Four Costs That Are Not Fuel
Fuel is roughly 40% of the real cost of running a diesel site. The other 60% is spread across four lines that never appear on the same report, which is exactly why they get ignored.
| Cost line | Typical share of ten-year total | What drives it |
|---|---|---|
| Fuel | 35–45% | Litres per year × local price. Highly volatile. |
| Fuel logistics | 10–20% | Distance from the depot, road condition, whether the site is reachable in the rainy season. In remote sites this often exceeds the fuel itself. |
| Theft | 8–15% | Industry experience is 10–20% of delivered fuel disappearing. It scales with how remote and how poor the site is. |
| Maintenance and servicing | 10–15% | Oil changes, filter changes, scheduled servicing visits. Each visit costs more than the parts because of travel. |
| Generator replacement | 8–12% | A genset running 12 hours a day needs replacing every 5–7 years. This is the line everyone forgets. |
Add those up and the ten-year cost of a diesel site is typically 2.5 to 3 times the fuel line alone. Any comparison that only counts fuel will always favour diesel, and will always be wrong.
What Solar-Hybrid Actually Replaces
Not all of the diesel. Anyone who tells you 100% is selling something. A properly sized solar-hybrid system replaces 70–85% of annual diesel consumption, and the remaining 15–30% is what keeps the site alive through a week of heavy cloud.
| Site load | Diesel per year (baseline) | After solar-hybrid | Reduction |
|---|---|---|---|
| 1 kW average, 24 kWh/day | ≈ 9,000 L | 1,400–2,700 L | 70–85% |
| 2 kW average, 48 kWh/day | ≈ 18,000 L | 3,000–5,400 L | 70–83% |
| 3 kW average, 72 kWh/day | ≈ 27,000 L | 5,000–8,000 L | 70–81% |
The reduction percentage drops slightly as load grows, because a larger site needs a larger battery to carry the same number of night hours, and there is a practical limit to how much PV you can mount on a compound.
The Sizing Rule That Decides Everything
Size the battery on the worst week of the year, not the average day. This is the single most important rule in off-grid design and the one most often broken, because average daily insolation is the number that is easy to find.
In a monsoon or harmattan climate, the worst week can deliver 35–45% of average daily solar. A system sized on averages will run the generator every night for two months and the fuel saving disappears. A system sized on the worst week costs 25–35% more upfront and delivers the saving every month of the year.
Average daily kWh is the number everyone quotes and the number that gets projects wrong.
The Container vs Cabinet Decision
Two shapes, two different site profiles. The choice is almost always made by access and security, not by electrical design.
| 20 ft solar-hybrid container | Outdoor DC cabinet (D02 class) | |
|---|---|---|
| Best for | Greenfield sites, new builds, sites with room | Rooftop, urban, wall-mounted, sites where a container will not fit |
| What is inside | PV input, lithium storage, −48 V rectifiers, generator interface, remote monitoring — factory-wired and factory-tested | Rectifier, lithium battery, controller and monitoring in one IP55 enclosure |
| Installation | Drop, anchor, connect PV and antenna, commission | Mount, connect DC and AC, commission |
| Lead time | Longer — it is a build, not a stock item | Shorter — closer to a catalogue product |
| Security | Better — one locked enclosure, harder to strip | Depends on the wall it is on |
For a site that already has a shelter and a compound wall, the cabinet is usually the cheaper answer. For a new build in a remote area, the container wins because it removes the need for a separate equipment room.
When Diesel Still Wins
There are real cases where solar-hybrid is the wrong answer, and a supplier who cannot name them is not worth listening to.
- Sites with less than three years of remaining life. The payback on solar-hybrid is typically 3–5 years. If the site is being decommissioned, keep the generator.
- Very low fuel price with reliable delivery. In a few markets with subsidised diesel and a depot next door, the economics genuinely do not close.
- Sites with no usable solar resource and no room for panels. Underground, heavily shaded or space-constrained urban sites.
- Loads above roughly 5 kW average. Above this the battery and PV array become large enough that a hybrid generator-plus-storage arrangement, or a grid connection, usually beats full solar-hybrid.
Frequently Asked Questions
How long does a solar-hybrid telecom system take to pay back?
Typically 3 to 5 years at current diesel prices and typical African and Middle Eastern fuel logistics costs. The variable that moves it most is not the equipment price — it is the cost of getting diesel to the site. A site 300 km from a depot pays back roughly twice as fast as a site 30 km away.
What happens during a week of no sun?
The generator runs. That is what it is there for, and it is why the system is called hybrid rather than solar. A correctly sized system will run the generator perhaps 20–40 hours a month in the worst season and near zero in the best.
Can I retrofit solar onto an existing diesel site?
Yes, and it is usually the fastest-payback version of the project because the tower, shelter, fence and access road already exist. The work is adding PV, storage and a controller that can start and stop the existing generator automatically. The generator itself usually stays.
How much of the site can run on battery overnight?
Design for 12 to 14 hours of battery autonomy on the average night load. Beyond that the battery cost rises faster than the fuel saving, and the generator becomes the cheaper source of night-time energy.
Send Us Your Site Data
Average load, antenna count, country and the distance to your fuel depot is enough for a first-pass ten-year comparison. We will tell you honestly if diesel is still the better answer for your site.