Generator Battery Hybrid Fuel Savings Calculator
Estimate how much generator fuel may be avoided when a battery handles low-load periods and the generator spends more of its runtime at a higher operating load.
Model generator fuel savings
Hybrid fuel result
How the hybrid fuel model works
The baseline assumes every generator hour uses the selected baseline fuel rate. The hybrid case keeps the generator running for the hours that remain and removes the selected low-load hours from generator fuel use. Battery charging electricity is deliberately reported separately because the goal of this tool is generator fuel savings, not net site energy savings.
Baseline fuel = Generator hours × Baseline fuel rate
Hybrid fuel = (Total hours − Shifted hours) × Preferred/remaining fuel rate
The calculator uses the low-load rate to quantify the fuel that would otherwise have been consumed during the shifted hours.
Why hybrid dispatch can matter
A generator can consume fuel even when the electrical load is relatively small. A battery can potentially serve short low-load periods while allowing the generator to operate during the higher-load portion of the duty cycle. The actual benefit depends on fuel curves, battery losses, charging source and dispatch controls.
Fuel saving is not the same as total energy saving
The battery requires charging energy. If that electricity comes from the generator, the fuel comparison must include the fuel required to create that charging electricity. This calculator intentionally exposes charging energy rather than silently treating it as free.
Limitations
- Fuel rates are user-entered.
- Battery charging and inverter losses are represented only through the charging-energy input.
- No generator fuel curve is created automatically.
- Battery degradation cost and capital cost are excluded.
FAQs
Can shifted hours equal all generator hours?
Yes mathematically, but that represents a case where the generator no longer operates during the modeled period.
Why enter both low-load and preferred-load fuel rates?
They represent different generator operating conditions and let the hybrid scenario explicitly reflect the changed duty.
Does this prove the battery saves money?
No. Fuel savings must be weighed against charging energy, battery degradation, capital cost and operating requirements.
Can charging electricity come from the generator?
Yes, but its fuel consequence should then be modeled separately rather than counted as free charging energy.