Summary:
Inverter Power Output Control (IPOC) allows installers to reduce or derate an inverter's maximum output power to meet specific project or regulatory requirements. This is especially useful in areas where utility programs impose a cap on residential inverters, or in repowering scenarios where a like-for-like replacement helps retain the original permitting without requiring new approvals. It also helps avoid costly main panel or service upgrades by aligning inverter output with the site’s interconnection limits.
For Tigo EI Inverters in the United States and Canada, derating options depend on the original model:
- For the 11.4 kW inverter, available settings include 10.0 kW, 9.6 kW, and 7.6 kW.
- For the 7.6 kW inverter, options include 6.0, 5.8, 5.0, 3.8, 3.0, 2.5, and 2.0 kW.
- For the 3.8 kW inverter, options include 3.0, 2.5, and 2.0 kW.
These selections ensure flexibility for regional compliance, system design constraints, and repowering needs. For more information on the value proposition of Inverter Power Output Control, visit tigoenergy.com/ipoc
Code Compliance
When the EI inverter’s maximum AC output current is reduced using IPOC (Inverter Power Output Control), the branch-circuit overcurrent device (PV inverter breaker) may remain at the existing rating, provided the configured inverter output current does not exceed the breaker’s continuous-current capacity.
The NEC defines inverter output as a continuous current source (NEC 705.30), therefore branch-circuit overcurrent protection is sized at not less than 125 % of the inverter’s maximum continuous output current (NEC 210.20(A), 215.3). IPOC effectively establishes a new maximum continuous output current for the inverter; if this limited current is equal to or less than the original inverter’s output current used to size the existing breaker (e.g., 24 A continuous on a 30 A breaker), the existing PV breaker remains correctly sized and NEC-compliant.
NEC 705.13 further permits power-control functions within the inverter to limit DER output so that conductor, busbar, and overcurrent-device ratings are not exceeded. Accordingly, when IPOC is commissioned and documented, replacement EI inverters may remain on the original PV inverter breaker without upsizing, provided the IPOC current limit and commissioning record are retained for inspection verification.
Step-by-step instructions:
Inverter power output control can be selected during commissioning in the Tigo EI App. These steps begin from the Configure Inverter portion of the EI Residential Solar Solution (US) commissioning process.
Step 1: Navigate to Derating Setting
- From the EI setup screen: Configure Inverter > Advanced Options > Power Derating
Step 2: Open Derating Options
- Tap Maximum Output Power to edit
Step 3: Choose Output Limit
- For the 11.4 kW inverter, select from: 10.0 kW, 9.6 kW, or 7.6 kW
Step 4: Select Desired Limit
- Example shown: 9.6 kW selected
Step 5: Confirm Change
- A warning will appear noting: “Change is permanent and logged.” Optional: Check “Lock setting after
confirmation”
Step 6: Lock and Confirm
- Once locked, the setting requires a factory reset to change.
Step 7: Confirmation Message
- A success message will confirm: “Power derating applied. Changes are permanent and logged.”
Step 8: Verify Final Output
- The final screen will show that the selected output is locked.
These steps complete the power derating setup process.
ATTENTION!
Please note that once the derating value is confirmed and locked, the change is permanent!
Be sure to double-check the selected value before confirming, especially in jurisdictions where system sizing and permitting are tightly regulated.
For repowering-specific information, Tigo offers a detailed repowering guide and a repowering checklist.
PN: TIG-ART-0006