Diesel Generator vs. Battery Power Generator: TCO and Cost per kWh
The purchase price of a petrol or diesel generator looks cheap – the truth is on the operating-cost sheet. This guide shows what a kilowatt-hour from a combustion engine really costs, which items belong in the Total Cost of Ownership (TCO), and from when a battery power generator like the GM 3600 is cheaper on balance.
The common mistake: purchase price is not TCO
A portable diesel generator is often cheaper to buy than a high-quality battery power generator. But the purchase is only a fraction of the total cost. Over the service life, ongoing costs arise for fuel, maintenance, idle consumption and – increasingly – for noise and emission requirements. Only the sum of all items gives the honest cost basis.
Cost per kWh: what diesel power really costs
A diesel generator consumes a fairly constant 0.3–0.36 litres of diesel per kWh generated – consumption per kWh barely drops, because the engine must run at constant speed regardless of the electrical load. Under part load it becomes even less efficient. Let's do the maths:
| Item | Assumption | Cost per kWh |
|---|---|---|
| Diesel consumption | ~0.33 l/kWh × ~1.70 €/l | ≈ 0.56 € |
| Oil / filters / service (pro-rata) | maintenance spread over operating hours | + 0.05–0.15 € |
| Idle / part-load loss | engine runs even without full load | + surcharge |
| Grid charging electricity (battery) | ~0.25–0.35 €/kWh commercial power | ≈ 0.30 € |
On fuel alone, the diesel generator sits at around 0.50–0.60 € per kWh – and that is the lower bound, without maintenance, idle consumption and fuel logistics. A battery power generator recharged from the grid overnight or during breaks incurs only the pure electricity cost – usually about half as much per kWh. How much energy you actually need is covered in the power-demand guide.
The hidden operating costs of the combustion engine
- Maintenance: oil changes, air/fuel filters, spark plugs, service intervals – recurring and labour-intensive.
- Idle & part load: the engine burns fuel even when no tool is running. A battery only delivers what is drawn.
- Fuel logistics: canisters, storage, theft risk, on-site refuelling – time and effort that are rarely counted.
- Noise & emissions: low-emission zones, night sites and interiors increasingly require emission-free, quiet power (more under emission-free construction site & low-emission zones).
- Downtime & starting issues: cold start, warm-up, carburettor problems – a battery power generator is ready at the push of a button.
5-year example: a rough TCO sketch
Assume a team uses a generator regularly, but predominantly under part load (typical for tool operation). Over five years, the costs shift clearly in favour of the battery:
| Cost block | Diesel generator | Battery power generator (GM 3600) |
|---|---|---|
| Purchase | lower | higher (from 2,999 € net) |
| Fuel / charging per kWh | ~0.50–0.60 € | ~0.30 € (grid) |
| Maintenance | oil, filters, annual service | low maintenance |
| Idle losses | yes | none |
| Emission/noise rules | restrictions, fine risk | uncritical |
| Indoor / night use | not permitted | possible |
The pattern is clear: the diesel generator wins on purchase but loses year after year in operation. The more often the unit runs, and the more it runs under part load, the faster the battery power generator pays for itself. The exact figures depend on operating hours, diesel/electricity price and service contract – the structure stays the same.
When the diesel generator still wins
To be fair: for very long continuous operation under high load with no charging option – e.g. multi-day large-scale operation far from any socket – the generator plays its fuel advantage. For typical hand and bench tool use with breaks and an overnight charging pause, however, the battery power generator is superior both practically and economically. A hybrid setup often makes sense too: battery quietly during the day, generator only to recharge.
Have the TCO calculated for your case Factual head-to-head comparison →Frequently Asked Questions (FAQ)
What does one kWh from a diesel generator cost?
Typically ~0.33 l diesel per kWh; at ~1.70 €/l that is ~0.56 €/kWh for fuel alone – without maintenance, idle and logistics. Often higher in reality.
Is a battery power generator cheaper in the long run?
In most construction-site scenarios, yes: grid recharging costs only a fraction per kWh, and there are no oil changes, filters, idle consumption or fuel storage. Over several years this usually offsets the higher purchase price.
What belongs in the TCO?
Purchase, fuel/charging electricity, maintenance, idle consumption, noise/emission rules, downtime and residual value – not just the purchase price.
Further reading: Battery power generator vs. diesel generator (head-to-head) · Emission-free construction site & low-emission zones · Product page & measured values GM 3600.
All cost and consumption figures are guide values from technical literature and practice (as of 07/2026) and serve as orientation; actual costs depend on the usage profile, fuel/electricity price and device. Prices net plus VAT, subject to change.