About this calculator
This calculator estimates the fuel cost of running a petrol or diesel generator during load-shedding or as a backup power source. Enter the fuel consumption in litres per hour (from the manufacturer spec sheet), the number of hours you run it, and the fuel price per litre.
The formula is simply Litres per hour × Hours × Rand per litre. A small 3 kVA petrol generator using 1 L/hr for 4 hours a day at R23/L costs R92/day, which adds up to about R2,760 per month — significantly more than the equivalent electricity from Eskom.
That's why generators are cost-effective for occasional use but expensive as a primary power source. For frequent, long-duration load-shedding, an inverter-and-battery UPS or a solar-and-battery system typically pays back within a few years compared with generator fuel costs. Don't forget to add oil and periodic servicing (roughly R0.50–R1.00 per operating hour) on top of the pure fuel cost, and factor in the cost of safe fuel storage.
How to use it
- 1Enter fuel consumption. Litres per hour from the manufacturer spec sheet.
- 2Enter running hours. Hours the generator will run in the period.
- 3Enter fuel price. Current Rand per litre at your local station.
- 4Read the cost. Total fuel cost over the period entered.