In short. Hybrid modernisation adds battery storage and smart control to an existing generator so it runs less, at better load, and with fewer starts. It suits sites with variable load or frequent short outages and needs engineered protection and control.
What changes
| Element | Role |
|---|---|
| Battery and converter | Carry short events and light load |
| Supervisory controller | Decides generator start, stop and charge |
| Generator | Runs at efficient load when needed |
| Protection | Coordinated for new fault sources |
Where it works
- Variable load with long light-load periods.
- Frequent short outages.
- Sites needing quieter, cleaner operation.
- Prime duty with peaks above average.
Where it does not
- Constant high-load duty: the generator runs anyway.
- Rare standby with no variable load.
Checks
- Measure the load profile in fine time steps.
- Define the control strategy and priorities.
- Study protection and fault levels. See fault level.
- Check generator paralleling and synchronising needs. See synchronisation.
- Plan commissioning tests. See commissioning.
See also DG plus BESS.
Illustrative example
A telecom hub with a small average load but occasional peaks runs its generator lightly for long hours. After a hybrid retrofit, the battery carries the base load, and the generator starts only to recharge at good loading.
Why generators run inefficiently in many sites
A generator sized for peak and emergency loads often runs at a small fraction of its rating for most hours. At light load, fuel consumption per kWh rises, combustion is poor, unburned fuel deposits in the exhaust, and engines suffer wet stacking. Hybrid operation changes the duty so the engine runs at a better load for shorter times.
Control strategies
| Strategy | What it does |
|---|---|
| Peak shaving | Battery covers peaks so a smaller generator can serve the site |
| Load following | Generator starts only when load exceeds what the battery can carry |
| Charge and rest | Generator runs at efficient load to charge, then stops |
| Spinning reserve replacement | Battery provides fast response so fewer generators need to idle |
Retrofit steps
- Log load at short intervals for several weeks.
- Simulate the strategies on the log to estimate run hours and fuel.
- Define equipment: battery, converter, controls.
- Study protection and fault levels.
- Design interlocks and safe fallback to generator-only operation.
- Install, commission, and tune.
Fallback is essential
If the hybrid controller or battery fails, the generator must be able to carry the full critical load on its own, with its own start and ATS logic. Never let a hybrid system make the original supply less reliable.
Maintenance changes
Fewer run hours mean longer oil change intervals by time but not by condition: do not stretch beyond maker limits. Batteries and converters need their own maintenance. Update the service plan.
Data and verification
Track hours, starts, fuel and energy. Compare against the pre-retrofit baseline. If the savings are less than predicted, adjust the strategy.
The master engineering question
Does the load profile leave enough light-load running to remove with a battery?
What to send us
Send load logs and generator data. Send your application details.
Questions engineers ask
Can any generator be hybridised?
Most can, with suitable controls; assess.
Does it need paralleling?
Depends on architecture.
What savings?
Calculate from the load profile.
Is a study needed?
Yes, for protection and control.
General guidance only. Values illustrative.