Why It Matters for Grid-Tied and Off-Grid Storage Applications
Why Frequency Matters in Power Systems
Every electrical grid — whether national, islanded, or microgrid — depends on a stable frequency (typically 50Hz or 60Hz). Even minor fluctuations can cause:
- Malfunctioning industrial equipment
- Premature wear on motors or transformers
- Total system instability or blackout
In the age of distributed energy, hybrid inverters are increasingly used not just for power conversion — but also for actively regulating frequency.
As a system buyer or project integrator, understanding how hybrid inverters contribute to frequency regulation helps you select the right models for reliable, grid-supportive projects.
1. What Is Frequency Regulation?
Frequency regulation (or frequency response) is the ability of a power source or load to detect frequency deviations and respond to them.
Two main types:
| Type | Description | Example |
|---|---|---|
| Primary regulation | Fast response (within seconds) to balance supply and demand | Hybrid inverter reduces output or boosts charging |
| Secondary regulation | Slower, coordinated adjustments to maintain frequency | EMS coordinates multiple inverters or batteries |
Hybrid inverters are ideal for primary frequency regulation in microgrids and distributed energy networks.
2. Why Frequency Fluctuates — Especially with Renewables
In grids with high solar or wind penetration, frequency instability becomes more common due to:
- Sudden drop in PV output (e.g., cloud cover)
- Load surges (e.g., factory motor startup)
- Reduced spinning reserve from traditional generators
Unlike diesel gensets, PV systems don’t inherently support grid frequency, unless hybrid inverters are configured with regulation capabilities.
3. How Hybrid Inverters Detect Frequency Changes
Most modern hybrid inverters use internal DSPs and firmware-based algorithms to:
- Continuously monitor grid frequency
- Compare it to system setpoint (50Hz or 60Hz)
- Adjust power flow from battery or PV accordingly
Key parameters:
| Parameter | Typical Setting |
|---|---|
| Frequency setpoint | 50.00 Hz / 60.00 Hz |
| Response range | ±0.2 Hz (adjustable) |
| Reaction time | 100ms–500ms |
Some models allow fine-tuning of frequency response via RS485 or Modbus commands.
4. Modes of Frequency Regulation in Hybrid Inverters
a) Grid-Tied Support Mode
Inverters feed power into the grid but reduce output if frequency rises — to avoid overloading.
- If grid frequency > 50.2 Hz → inverter reduces output
- If grid frequency < 49.8 Hz → inverter may increase output (if PV/battery allows)
This helps utilities stabilize frequency without dispatching large generators.
b) Off-Grid or Microgrid Mode
In this mode, the inverter acts as the frequency leader — setting the reference for other components.
- Inverter output must remain at 50Hz ± 0.1Hz
- Load changes are managed via BMS + inverter logic
- Some systems combine diesel gensets and hybrid inverters, with frequency sync logic
For tourism resorts or rural networks, this ensures appliance protection and system coordination.
c) Battery Frequency-Watt Control (Droop Control)
Some advanced hybrid inverters implement a “droop curve”:
- Frequency drops → inverter increases battery output
- Frequency rises → inverter reduces battery output or starts charging
This mimics the behavior of rotating generators and helps integrate storage into grid frequency planning.
5. Technical Example: Deye, Growatt, Victron
| Brand | Frequency Regulation Feature | Notes |
|---|---|---|
| Deye | Adjustable droop settings in parallel inverter setups | Used in microgrids with genset sync |
| Growatt SPF | Limited frequency response, suitable for basic backup | Grid-tied models support FR in select firmware |
| Victron Multiplus/Quattro | Grid code compliant FR via GX device + ESS firmware | Common in Europe, Africa |
| SMA Sunny Island | Built-in frequency shift and control | Suitable for multi-inverter island grids |
Always check if firmware supports grid code requirements (e.g., EN 50549, IEEE 1547).
6. How System Buyers Can Leverage Frequency Regulation
As a buyer or system designer, supporting frequency regulation gives you:
- Grid compliance for regions with strict interconnection rules
- Better diesel-battery hybrid performance in rural power projects
- Improved lifetime of batteries via controlled charging/discharging
- Extra service revenue in regions with frequency response markets (e.g., UK, Germany)
It’s not just about “selling power” — but about “supporting the grid.”
7. Design Tips: Making Frequency Regulation Work
✅ Choose hybrid inverters with firmware-level FR support and adjustable response parameters
✅ Ensure battery BMS communication supports droop or frequency-watt logic
✅ Use EMS for multi-inverter coordination if load >20kW
✅ Test under load conditions (especially motor-heavy or inductive environments)
✅ Document frequency setpoints and logic in system diagrams for easier commissioning
8. Final Word: Frequency Is the New Voltage
While most customers still ask “How many kilowatts?”, system reliability increasingly depends on how well your system handles frequency.
Hybrid inverters that support frequency regulation are:
- More grid-friendly
- More resilient in off-grid/microgrid use
- More future-ready as energy systems become decentralized
Don’t just look at power specs — ask your supplier:
“How does this inverter respond to frequency deviations?”
