Load Shedding Generator Cost Calculator
When the grid fails, a diesel generator keeps the plant running at a much higher cost per kWh. This calculator shows that cost, how it moves with the diesel price and the annual premium over grid power, so you can cost outages in your product margins.
Your numbers
Measured average electrical load while on the generator.
From the set's fuel curve or your own logs.
Blended energy cost including demand charges if you wish.
Service, oil and wear per kWh produced.
Your results
Estimate only. Fuel burn changes with load, set size and condition. Excludes capital cost, lost production and theft or spillage. Use measured data for decisions.
Generator cost per kWh vs diesel price
Sweeps Diesel price from 15 to 35, holding your other inputs fixed.
Link outage cost to production orders
Optional: we can show how outage hours and energy flow into job costs from your ERP data.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the average load your generator carries, the fuel it burns at that load, the diesel price and the hours it runs. Add your grid tariff and a maintenance cost per kWh. The result shows the cost per kWh from the generator, the total annual running cost and the premium compared with buying the same energy from the grid. The chart shows how sensitive that cost is to the diesel price.
The formula
Fuel cost per kWh is litres burned per hour times the diesel price, divided by kWh produced per hour. Because kWh per hour equals the average kW load, the figure is simply litres per hour times price divided by kW. Add maintenance cost per kWh for the full running cost. A lightly loaded set burns more fuel per kWh, so measure real load rather than the nameplate rating.
- Cost per kWh = litres per hour x price / kW + maintenance
- Premium = kWh x (generator cost - grid tariff)
- Low load factor raises the cost per kWh
Using the result
Compare the premium with options such as solar with batteries, load scheduling or a bigger fuel tank. Feed the generator cost into job costing for products made during outages, or add it as an overhead line. Remember that this excludes lost output when the set cannot carry the full plant, which is often the larger cost.
- Allocate outage energy to the products run during the outage
- Test the diesel price range on the chart
- Add capital cost when comparing alternatives
Frequently Asked Questions
What fuel burn should I enter?
Use the set's fuel consumption at your typical load from the manufacturer's data, or better, your own logs of litres used and hours run. Fuel burn per hour at 50 percent load differs from full load.
Why is my cost higher than expected?
Low load is the usual reason. A large generator running at 30 percent load burns far more fuel per kWh than one sized to the load. Fuel loss and idling time also add to the real cost.
Does this include the cost of lost production?
No. It covers energy only. If the generator cannot carry every machine, lost output and idle labour during the outage can exceed the fuel cost, so estimate them separately.
Can I use it for other countries?
Yes. Enter your local diesel price and grid tariff. The currency prefix is rand but the maths works in any currency if you keep all inputs in the same one.
If you want outage hours, energy and downtime linked to your production orders in the ERP, we can build that reporting over your existing data.
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