Can I get the battery rebate if I already have solar?

Generally, yes. The storage rebate of about $300 per kWh applies to batteries whether or not they're installed with new solar, with virtual power plant enrollment required. Confirm eligibility for your system with your utility or installer.

What battery works with my existing solar panels?

AC-coupled batteries such as FranklinWH aPower 2 and Enphase IQ batteries are designed to add on to existing systems. Have an installer confirm compatibility with your inverter.

Adding a Battery to Existing Solar in Illinois (2026)

Q: Will adding a battery affect my net metering?

It might. Ask your installer and utility in writing whether a battery changes your current net metering terms or requires a specific rate plan, especially if your solar was connected before 2025.

Quick answer

Yes, you can add a battery to existing solar in Illinois, and it can still earn the ComEd or Ameren storage rebate of about $300 per kWh, around $4,050 for a 13.5 kWh battery. AC-coupled batteries like FranklinWH aPower 2 and Enphase IQ batteries are built to add on, and the battery must be enrolled in the utility's virtual power plant.

Can I add a battery to my existing solar system?

Usually, yes. An AC-coupled battery connects on your home's electrical side instead of to the panels, so it works alongside the inverter you already have. FranklinWH says aPower 2 works with existing solar from other brands, and Enphase batteries are the natural fit for homes that already have Enphase microinverters. Tesla Powerwall 3 can be added to some systems, depending on the inverter, so have the installer confirm compatibility in writing.

Why add a battery to solar I already have?

Backup power. Grid-tied solar shuts off in an outage; a battery keeps chosen circuits running and lets the panels recharge it.
Better value from newer systems. Solar connected since 2025 earns only the supply rate for exports, so storing midday power for the evening is worth more.
The rebate. The storage rebate of about $300 per kWh is set in state law through 2029.

Will adding a battery change my net metering?

It can, so ask before you sign. Homes with solar connected before 2025 kept full retail net metering, and rule changes for adding equipment differ between the solar rebate and the battery rebate. Newer systems already earn supply-rate credits. Ask your installer and utility, in writing, whether the battery changes your current net metering terms or requires a specific rate plan.

See how Illinois net metering works now and adding panels to an existing system.

What does adding a battery involve?

1
Check your panel and inverter
The installer confirms the battery works with your inverter and that your electrical panel has room.
2
Choose what to back up
Essential circuits or the whole home, which may need a gateway or backup panel.
3
Permits and utility approval
Your town permits the electrical work, and ComEd or Ameren approves the interconnection.
4
Rebate and VPP enrollment
The installer files the storage rebate and enrolls the battery in the utility's virtual power plant.

See how the ComEd and Ameren virtual power plants work.

What should I ask installers about adding a battery?

Is the battery compatible with my inverter, and does adding it affect my panel or inverter warranty?
Will my net metering terms or rate plan change?
What will run during an outage, and for how long?
What's the price before and after the storage rebate?

Compare costs in how much a home battery costs in Illinois.

Sources

This guide is general information, not tax, legal or financial advice. Incentive programs change, so confirm current terms with your installer, your utility and a tax professional.

Adding a battery to the solar panels you already have