Support Articles
PV curtailment appears because the grid or your inverter intentionally limits solar output to maintain grid stability, voltage/frequency limits, or export rules—not because the system is faulty.
1>. Grid demand response causes
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Grid Overvoltage (Local): Too much solar on a feeder raises voltage above limits (typically >1.05 pu). Inverters throttle output (Volt-Watt) or absorb reactive power (Volt-VAR) to bring it back in range.
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Midday Oversupply (System): Peak solar (10:00–15:00) coincides with low demand. Supply > load, and baseload plants can’t turn down far enough—so grid operators cut solar.
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Transmission Congestion: Lines/transformers hit capacity; “can’t send” power away from the solar-rich area.
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Export Limits: Utility rules cap how much power you can feed back (e.g., 70% of inverter rating).
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Frequency Regulation: Sudden solar spikes push grid frequency too high; inverters or dispatch curtail to stabilize it.
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Inverter/Setting Limits:
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Max export set too low (e.g., 5kW on a 10kW inverter).
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Grid code requirements (e.g., voltage-dependent power reduction) are enabled.
Quick Checks
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Time & Weather: Common at midday, sunny, low-demand periods (weekends, holidays).
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Inverter Alarms: Look for “Voltage Reduction,” “Grid Support,” or “Export Limit Active.”
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Utility/Grid Status: Check if your area has known congestion or voltage issues.
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Settings: Confirm max export limit and grid code settings match your utility’s requirements.
Key Point
Curtailment is normal and protective, not a system fault. It protects the grid and your equipment.
2>. Multi PV Strings Non-Export Setting
FranklinWH allows each PV string to be configured as export or non-export to comply with contracted utility programs.
Common examples include:
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HECO CSS: full non-export configuration
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HECO NEM+: new PV strings set to non-export
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California NEM-MT tariff: new PV strings set to non-export
Once the FranklinWH aPowers battery is fully charged, power generation from non-export PV / new non-export PV strings will be curtailed.
3>. PV Curtailment Protection When Grid dropping off
FranklinWH adopts protection logic that curtails PV output first when the grid drops offline, regardless of whether AC PV or DC PV is installed.
After several minutes, AC PV and DC PV will be restored sequentially one by one.
4>. Automatic PV Curtailment in Off-Grid Mode
The FranklinWH system integrates inverter frequency-droop control for AC PV curtailment, and aPower S MPPT control for DC PV curtailment.
This function dynamically regulates PV generation (kW) to ensure it does not exceed the total power consumption of home loads plus aPowers battery charging demand.
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