State of Charge Recovery for an Enphase Energy System
Document ID: TEB-00084-1.0
Date: November 2023
Overview
This document outlines the procedure and equipment required to recover an Enphase Energy System when it stops forming a microgrid due to excessive battery discharge. This situation typically occurs during extended utility grid outages when solar power is limited or unavailable. The steps provided are applicable during battery charge depletion events, such as those caused by natural disasters like hurricanes. This technical brief supplements information found in datasheets, quick install guides, and product manuals, and may not cover all local code requirements.
The Enphase storage system features built-in intelligence for automatic battery charge recovery. This brief details steps to recover batteries in emergency scenarios where they are completely discharged, for instance, due to a prolonged absence of solar production during a grid outage.
This technical brief applies to the following IQ System Controllers and IQ Batteries:
| Model | SKUs |
|---|---|
| IQ System Controller 1 | EP200G101-M240US00 |
| IQ System Controller 2 | EP200G101-M240US01/EP200G-SC2-RSD-BRK-KIT |
| IQ System Controller 3/3G | SC200D111C240US01/SC200G111C240US01 |
| IQ Battery 3T | ENCHARGE-3T-1P-NA |
| IQ Battery 10T | ENCHARGE-10T-1P-NA |
| IQ Battery 5P | IQBATTERY-5P-1P-NA |
Automatic Charge Recovery
When an Enphase Energy System is operating in backup mode (forming a microgrid), IQ Batteries will stop discharging once their State of Charge (SoC) reaches a very low SoC limit (VLS), defaulting to 10% (configurable by the homeowner). The automatic charge recovery algorithm initiates under the following conditions:
- The algorithm functions when the battery SoC is between 2% and 10%.
- The system restarts, forms a microgrid, and attempts to charge from available solar power.
- The algorithm employs an exponential timeout between restart attempts: 10 minutes, 20 minutes, 40 minutes, and 120 minutes. The maximum timeout is 120 minutes, meaning the system will attempt to form a microgrid and charge batteries from solar every 120 minutes.
- Each charging attempt lasts a maximum of six minutes or until the battery loses 0.5% SoC, whichever occurs first. If charging is unsuccessful within this timeframe, the battery will stop forming the microgrid and retry after the timeout period.
- When the battery SoC reaches 2% or lower, the automatic charge recovery algorithm deactivates, and all battery electronics shut down to prevent irreversible damage.
- This recovery algorithm operates only during periods of good solar production, typically between 9:30 AM and 5:30 PM local time, to avoid wasting battery charge overnight.
? NOTE: The automatic charge recovery feature described applies to systems using IQ Gateway software version 7.03.XXX and above.
? NOTE: For successful automatic charge recovery, homeowners must turn off all loads in the home to ensure a microgrid can form without overloading and allow batteries to charge.
Emergency Charge Recovery Using Portable Generators
Portable generators can be used for emergency recovery when batteries cannot recover automatically, their SoC is below 2%, or the homeowner cannot wait for automatic recovery.
⚠️ WARNING: This procedure involves working with high-voltage, current-carrying conductors. It should only be attempted by certified Enphase installers and qualified electricians. This procedure is strictly for recovering battery state of charge and not for continuously powering home loads. Running home loads with a generator and batteries or solar in parallel can damage loads, Enphase equipment, and the generator. For the correct method of using backup generators in parallel with batteries and/or solar, refer to the "Generator with Enphase Storage Tech Brief."
Secure the Necessary Equipment Before Visiting the Site
Portable Generator
A 120/240 VAC portable inverter generator is required. The Enphase Energy System supports only the generators listed below for this recovery procedure. Using other generators may result in failure to charge batteries or damage to the generator or Enphase equipment.
| Make | Model | Nameplate | Outlet to be used |
|---|---|---|---|
| Predator | 8750 (SKU: 57480) | Starting wattage: 8,750 W Running wattage: 7,000 W |
120/240 VAC 30 A (L14-30R) receptacle |
| Champion | 6250 (SKU: 100519) | Starting wattage: 6,250 W Running wattage: 5,000 W |
120/240 VAC 30 A (L14-30R) receptacle |
| Powerhorse | 4500i (SKU: 83171) | Starting wattage: 4,500 W Running wattage: 3,700 W |
120/240 VAC 30 A (L14-30R) receptacle |
An inverter generator producing a clean sine wave is essential to ensure the generator's power quality meets the voltage and frequency limits supported by the IQ System Controller and IQ Batteries. Enphase has tested these generators to confirm compliance.
? NOTE: Acceptable voltage and frequency variations and total harmonic distortion are:
- Line-to-line voltage (0.5–1.2 pu)
- Frequency: 56 Hz–64 Hz
- Total harmonic distortion (THD) < 10%
Generator Extension Cord Stripped to Work with the IQ System Controller
A 10-gauge (10 AWG), generator-duty, twist-lock extension cord rated for 120/240 VAC, 30 A is required. This cord typically has a NEMA L14-30P plug for the generator and an L14-30R receptacle on the other end. For connection to the IQ System Controller, the female plug on the generator end must be cut off, and the L1, L2, ground, and neutral wires must be stripped appropriately.
Multitap Connectors and Wire (2 AWG to 14 AWG)
The AC combiner lugs in the IQ System Controller are rated for 2 AWG to 14 AWG Cu/AL wires. Use insulated multitap connectors to connect the 10 AWG L1 and L2 wires from the generator extension cord to the IQ System Controller lugs. It is recommended to have at least two multitap connectors, one for L1 and one for L2. An example of a suitable connector is the Polaris double-sided entry, insulated multitap connector with 2 ports, supporting conductor sizes from 14 AWG to 1/0 AWG. Use one port for the generator connection. If the IQ Gateway needs to be powered, use the second port to power the IQ Combiner.
Procedure
When the battery state of charge reaches 2% or lower, the automatic charge recovery algorithm deactivates, and battery electronics shut down to prevent irreversible damage. Follow this procedure to recover batteries from a very low state of charge.
⚠️ WARNING: This procedure involves multiple high-voltage power sources. Follow the steps precisely in the stated sequence for installer/electrician safety.
Step 1. Turn OFF the Grid Supply to the IQ System Controller
Disconnect the utility supply from the IQ System Controller to de-energize conductors entering the utility input.
- If a utility system disconnect exists outside the IQ System Controller, turn it OFF.
- If a panel is on the utility side, turn OFF the breaker feeding the IQ System Controller.
- If the IQ System Controller acts as service equipment with an internal utility breaker, ensure service conductors cannot be energized and turn OFF the CSR breaker within the IQ System Controller.
Step 2. Turn OFF the DC Switches in All IQ Batteries
- For IQ Battery 3T (ENCHARGE-3T-1P-NA) and IQ Battery 10T (ENCHARGE-10T-1P-NA), turn off the DC switch by opening the top cover.
- The IQ Battery 5P's LED-based DC switch is power-activated. If the battery SoC is less than 2%, it may not be possible to turn it OFF. The IQ Battery 5P automatically turns off at very low SoC (<2%) to prevent further discharge and avoid entering a non-recoverable mode.
- It is recommended to physically disconnect all batteries not specifically intended for recovery purposes.
Step 3. Turn OFF All PV Branch Circuit Breakers
Turn OFF all PV branch circuit breakers in the IQ Combiner or sub-panel used to aggregate solar.
- Ensure all PV branch circuit breakers are OFF.
- Ensure the IQ Gateway breaker is ON if the IQ Gateway is powered from the load center in the IQ Combiner.
Step 4. Confirm Breaker States in the IQ System Controller
- Ensure the AC combiner breaker (PV breaker) is ON.
- Ensure the NFT breaker is OFF.
- Ensure the IQ Gateway breaker is ON if powered from the load center.
- Ensure the IQ Battery breaker is ON.
- Ensure the backup loads breaker, if present, is OFF. If not, turn OFF the main supply breaker in the backed-up loads panel.
- Ensure RSD is disengaged.
Step 5. Prepare the Generator for Connection
- Ensure the generator is OFF.
- Ensure the generator has been filled with fuel and oil.
Step 6. Connect the Generator to the IQ System Controller
Connect the generator extension cord to the generator, inserting and locking the L14-30P male plug into the generator's L14-30R receptacle. Remove the IQ System Controller dead front. Disconnect the PV combiner Port L1 and L2 conductors.
Use the correct wiring diagram for the system controller based on its SKU, as diagrams may vary.
Wiring Diagrams Description:
The document includes three wiring diagrams (Figures 1, 2, and 3) illustrating connections within the IQ System Controller for different SKU groups. These diagrams depict the internal layout, including components like the AC Combiner, Generator input, Load Breaker, Mains Relay, Mains Breaker, and connections for IQ Battery, IQ Gateway, and Backup Loads. They also show grounding and bonding points. Specific notes accompany each diagram, detailing applicability for certain microinverter types (e.g., IQ8 vs. non-IQ8) and instructions for parallel connection of the IQ Gateway and generator using multitap lugs when necessary.
? NOTE: For systems with non-IQ8 Microinverters, the IQ Gateway is powered via a breaker in the IQ Combiner. Disconnecting the combiner port turns off the IQ Gateway. In such cases, the IQ Gateway and generator should be connected in parallel using Polaris multitap lugs for simultaneous connection.
Step 7. Turn ON the Generator
- Check oil and fuel levels.
- Turn ON the fuel valve.
- Move the choke to the CLOSED position.
- Turn ON the engine switch to start the generator electrically, or use the recoil/pull start.
- Move the choke to the OPEN position.
Step 8. Observe the System
The installer/electrician does not need to take action in this step; observation is key.
- Once the generator starts, the IQ System Controller will power up using generator power.
- Verify system function by opening the IQ Combiner containing the IQ Gateway. The four IQ Gateway LEDs should be blinking red, indicating it is powered and booting. If delayed, at least one LED should be lit green or red.
- After booting, the IQ Gateway will connect to the IQ System Controller via Zigbee (for IQ System Controller 2) or control bus (for IQ System Controller 3/3G).
- The IQ Gateway will attempt to connect to IQ Batteries via Zigbee/Control bus but may fail if batteries are at very low SoC (<2%). After approximately 15 minutes (5 mins for Gateway boot + 10 mins for battery timeout), the IQ Gateway will command the IQ System Controller to close the IQ Battery relay. An audible click may be heard, and IQ Battery unit LEDs will blink red, indicating AC power.
Step 9. Turn ON the DC Switches
- For IQ Battery 3T (ENCHARGE-3T-1P-NA) and IQ Battery 10T (ENCHARGE-10T-1P-NA), turn ON the DC switch as per the table.
- The IQ Battery 5P's LED-based DC switch activates with battery power. If SoC is <2%, it may not be possible to turn ON; it turns on automatically when charge is recovered from the generator.
⚠️ WARNING: To avoid overloading the generator, only switch ON batteries specified in the table. It is recommended to physically disconnect all other batteries and connect only those intended for recovery.
Battery Charging Capacity by Generator Wattage
The following table indicates the maximum quantity of IQ Batteries that can be switched ON for charging with a specific generator wattage.
| Make | Model | Nameplate | Maximum quantity of IQ Batteries switched ON for charging | ||
|---|---|---|---|---|---|
| IQ Battery 3T (1.28 kW)/(3.36 kWh) | IQ Battery 10T (3.84 kW)/(10.08 kWh) | IQ Battery 5P (3.84 kW)/(5.0 kWh) | |||
| Predator | 8750 (SKU: 57480) | Starting wattage: 8,750 W Running wattage: 7000 W |
5 | 1 | 1 |
| Champion | 6250 (SKU: 100519) | Starting wattage: 6,250 W Running wattage: 5000 W |
3 | 1 | 1 |
| Powerhorse | 4500i (SKU: 83171) | Starting wattage: 4,500 W Running wattage: 3,700 W |
2 | 0 | 0 |
? NOTE: Do not overload the generator. Switch ON DC switches in IQ Batteries based on their power rating and the generator's rating. The total power required for charging batteries must be less than the generator's output power.
- IQ Battery unit LEDs will pulse softly green when charging with the DC switch ON. A current clamp multimeter can verify charging by connecting to L1 or L2 wires from the IQ Battery to the IQ System Controller.
- Initial charging may take up to 20 minutes, with a potentially low rate. The rate will increase once batteries recover to more than 2% SoC.
- If batteries are not charging after 20 minutes, contact Enphase Support for assistance, including opening a secure connection (tunnel) to the IQ Gateway.
Step 10. Verify Battery Charge and Continue Charging if Necessary
Verify that IQ Battery units have charged to the desired SoC. If applicable, charge remaining IQ Battery units.
To check the IQ Battery SoC:
- Press the Access Point (AP mode) button on the IQ Gateway; the AP mode LED should light up green.
- Connect your phone to the IQ Gateway's Wi-Fi network.
- Open the Enphase Installer App and navigate to the site being recovered.
- Go to Devices and Array > IQ Battery > <serial number of IQ Battery being recovered> and check the SoC.
- Repeat these steps for all IQ Battery units being charged.
If charging during daytime with good irradiance, charging can stop when batteries reach 15% SoC, as they can charge further from solar power later.
? NOTE: If charging during poor irradiance or at nighttime, stop charging when SoC is higher than 75%, or preferably wait until batteries are fully charged (100% SoC).
- Once batteries reach the desired level, turn OFF the DC switches for those units.
- Repeat the process for the next set of batteries for charging and recovery.
Step 11. Disconnect and Turn OFF the Generator
- Turn OFF the engine switch on the generator.
? NOTE: Do not turn OFF the generator if batteries are not adequately recovered, as this could leave the system in a non-recoverable state. If this occurs, contact customer support.
- Turn OFF the fuel valve on the generator.
- Disconnect the generator extension cord from the L14-30R receptacle on the generator.
⚠️ WARNING: Do not touch the prongs of the L14-30P plug on the generator extension cord. Measure L1 to L2 voltage on the combiner lugs of the generator connection to ensure there is no voltage and the lugs are de-energized before proceeding.
- Disconnect the generator L1, L2, neutral, and ground wires from the IQ System Controller.
Step 12. Restore the System to the Normal Operating State
- Turn OFF the DC switches on all IQ Batteries.
- Reconnect the IQ Combiner L1 and L2 conductors to the IQ System Controller.
- Reinstall the IQ System Controller's dead front.
- Turn ON the NFT breaker.
- Turn ON the utility side breaker or disconnect that was turned OFF in Step 1, or reinsert the meter if it was pulled out.
- Turn ON the DC switches on all IQ Batteries.
- Verify the IQ Batteries are discharging; the LED on each unit will be pulsing blue.
- Turn ON the PV branch circuit breakers in the IQ Combiner or solar aggregation subpanel that were turned OFF in Step 3.
- If IQ Batteries were charged to 15% SoC:
- Open the Live Status item in the Enphase Installer App and check that PV is producing and batteries are charging.
- Wait until batteries reach SoC higher than 75%, or preferably wait until they are fully charged (100% SoC).
- Ensure only essential backed-up loads are turned ON in the home.
- Turn on the backup loads breaker or supply breaker in the backed-up loads panel that was turned OFF.
? NOTE: PV may take 15 seconds to 5 minutes to start producing power, depending on the grid profile and site.
Step 13. Final System Operation Verification
The home should now be operating in a microgrid with the IQ Batteries fully functional.
- Verify loads using the Live Status screen in the Enphase Installer App.
- Discuss with the homeowner whether the system can supply loads through the night and retain more than 10% SoC to ensure it starts charging from PV the next day.
- Ensure the owner is aware of the system's capacity and adjusts consumption habits to use power judiciously during a sustained outage.
Revision History
| Revision | Date | Description |
|---|---|---|
| TEB-00084-1.0 | November 2023 | Revised the procedure for SoC recovery. |
| Previous releases. |
