Generator Running Cost Calculator
Calculate your generator running costs for load shedding. Compare fuel costs, maintenance, and 5-year TCO against a battery inverter system.
Quick Calculator Get a fast estimate
W
%
h
Monthly Fuel Cost
R 535
Fuel Used
24 L/month
Monthly Maintenance
R 25
Total Monthly Cost
R 560
Annual Cost
R 6 715
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Generator Fuel Consumption
Fuel consumption = Generator kW × Load % × 0.33 L/kWh. A 3.5 kW generator at 60% load uses 3.5 × 0.6 × 0.33 = 0.69 L/hour. At Stage 2 (4h/day × 30 days = 120h/month) and R22.50/L, that's R1,862/month in fuel alone — not counting maintenance.
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Extended Calculator More options, charts, and scenario comparison
kW
%
h
R/L
Monthly Generator Cost
R 1 069
Fuel/month
48L
Annual fuel
R 12 830
Annual maintenance
R 630
Generator Fuel Efficiency by Size
| Generator | Fuel @ 60% Load | Monthly Cost (Stage 2) |
|---|---|---|
| 1.0 kW | 0.20 L/h | R 540 |
| 2.0 kW | 0.40 L/h | R 1,080 |
| 3.5 kW | 0.69 L/h | R 1,863 |
| 5.0 kW | 0.99 L/h | R 2,673 |
| 7.5 kW | 1.49 L/h | R 4,023 |
Need full precision?
Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown
5-Year Generator Total Cost of Ownership
kW
R
%
R/L
%
%
5-Year Total Cost of Ownership
R 147 924
Month 1 fuel
R 1 871
Year 1 fuel
R 22 453
Year 5 fuel
R 30 547
Year-by-Year Breakdown
| Year | Fuel Price | Fuel Cost | Maintenance | Annual Total |
|---|---|---|---|---|
| Year 1 | R22,5/L | R 22 453 | R 840 | R 35 293 |
| Year 2 | R24,3/L | R 24 249 | R 840 | R 25 089 |
| Year 3 | R26,24/L | R 26 189 | R 840 | R 27 029 |
| Year 4 | R28,34/L | R 28 285 | R 840 | R 29 125 |
| Year 5 | R30,61/L | R 30 547 | R 840 | R 31 387 |
Generator Maintenance Checklist
- Change oil every 50–100 hours (petrol) or 100–200 hours (diesel)
- Clean/replace air filter every 25 hours or annually
- Check spark plugs every 100 hours
- Run generator at 50%+ load — avoid light loading (wet stacking)
- Use fuel stabiliser if storing for more than 30 days
- Check coolant level (liquid-cooled generators)
- Test under load monthly even during non-load-shedding periods
SA Tip: Petrol generators are cheapest upfront but diesel is 15–25% more fuel-efficient per kWh generated. For generators running 60+ hours/month, diesel typically pays back the price premium within 12–18 months.
Frequently Asked Questions
Change oil every 50–100 hours for petrol or 100–200 hours for diesel. At Stage 2 load shedding (120 hours/month), this means an oil change every 1–2 months for petrol. Budget R1,500–R3,000/year for professional servicing and consumables.
Never run a petrol or diesel generator indoors or in an enclosed space. Carbon monoxide poisoning causes multiple deaths each year during load shedding. Generators must be placed outdoors with adequate ventilation, at least 1.5 metres from windows and doors.