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What is your generator actually costing you?
Put in what you run and how it runs. We will show you the fuel, the engine hours and the servicing — then the same job done with a battery in front of it.
Your set-up
Estimates are fine. Nothing here is sent anywhere unless you ask.
Servicing and power factor
Fill in your set-up
The numbers update as you type.
| As it runs now | With a battery | |
|---|---|---|
| Fuel used | — | — |
| Fuel cost | — | — |
| Engine hours | — | — |
| Services a year | — | — |
| Servicing cost | — | — |
| Total running cost | — | — |
| Litres per useful kWh | — | — |
| CO₂ | — | — |
What that would take
Want us to check it properly?
These are estimates from a standard fuel model. We will meter your site for a fortnight and give you the real figure — at no cost, and with no obligation.
How the numbers are worked out
No black box. Here is the model, so you can argue with it.
Fuel consumption
A diesel generator's consumption is close to linear in two parts — a fixed cost simply for turning over, plus a variable cost for the power it actually delivers:
litres per hour = 0.08 × rated kW + 0.20 × delivered kW
That gives about 0.28 litres per kWh at full load and about 0.52 litres per kWh at quarter load, which matches published consumption figures for modern sets. The fixed part is the whole problem: it is there whether you are drawing 5 kW or 50.
What the hybrid does
The battery carries the quiet-period load with nothing running. The engine starts only to recharge and to cover real peaks, and it runs at around 80% of its rating while it does — where a diesel is close to its best. We apply a 90% round-trip efficiency to everything that passes through the battery, because that loss is real and pretending otherwise would flatter the result.
Servicing
Assumed at 500 engine hours between services. Fewer hours means fewer services, and that saving is included alongside the fuel.
What this model cannot know
It uses two load figures — quiet and busy — where a real site has a load profile that moves all day. It assumes a well-maintained engine. It does not know your starting currents, your access for refuelling, or what a battery enclosure would cost to site securely.
It is good enough to tell you whether the conversation is worth having. It is not good enough to spend money on. That is what metering is for, and we do that free.
Why we let it say no
If you put in a site that runs near full load, this calculator will tell you hybrid would make things worse — because it would. Pushing energy through a battery costs you the round-trip loss, and if the engine was already working hard there is no light-load running to remove.
A calculator that recommends the sale whatever you type into it is not a calculator, it is a brochure with sliders.
The estimate is free. So is the metering.
We will put a meter on your site for a fortnight and tell you what the real number is — including if the answer is that you should leave it alone.
Arrange a survey