Solar words, in plain English

These are words you will see on solar quotes, contracts and your electric bill in Illinois. Each one gets a short, plain meaning. Tap a number to see where it comes from.

Approved Vendor

A company Illinois Shines approves to sign up solar projects. The credit contracts run through Approved Vendors, not each homeowner, and your Approved Vendor sells the credits to the utility. How to check a company.

Battery

A home battery stores power so you can use it later, like when the grid goes down. If a battery is part of the offer, you should see battery costs and fees on the Disclosure Form. Batteries in an outage.

Customer charge

A charge on your electric bill that stays the same whatever you use. Solar credits do not cover customer charges and fees that do not depend on how much power you use.

Delivery charge

What you pay the utility to carry power to your home over its wires. With new solar, you pay delivery charges on all the power you pull from the grid.

Disclosure Form

The Illinois Shines form that lays out your offer in plain terms. You sign the Disclosure Form before the contract, and the agent must go through the whole form with you and take your questions. Our Disclosure Form guide.

Federal solar tax credit (25D)

The federal income tax credit for home solar you buy yourself. It is not available for property placed in service after December 31, 2025. On a lease or a PPA, the federal credit is not available to the homeowner on their tax return. Our tax credit guide.

Interconnection

Getting the utility's OK to connect a solar system to the grid. Ask your installer who handles it and how long it takes.

Inverter

The box that changes the power your panels make into the kind your home uses. Panels make direct current (DC), and your home runs on alternating current (AC).

kW (kilowatt)

A unit of power. Solar systems are sized in kW. The more kW, the more power the panels can make at once.

kWh (kilowatt-hour)

An amount of energy. Your bill charges you by the kWh. The average price Illinois homes paid in August 2026 was 19.32¢ per kWh, statewide.

Lease

A solar company puts panels on your roof and keeps owning them, and you pay to use them. On a lease or a PPA, the system is owned by the solar company, not the homeowner.

Net metering

In Illinois Shines words, a credit on your bill for the power your panels send to the grid. New systems get credit for supply charges only. Our net metering guide has the details.

PPA (power purchase agreement)

A company puts panels on your roof and owns them, and you pay a set price per kWh for the power the system makes. The contract must say the price, and any yearly increase. Our PPA guide.

REC (renewable energy credit)

A credit for the environmental value of solar power, not the power itself. Illinois Shines provides payments for the solar credits a system makes over 15 or 20 years, depending on system type. How Illinois Shines works.

Right to cancel

After you sign an Illinois Shines contract, you have three or more calendar days to cancel, for systems of 25 kW or less. You should get copies of what you signed within 24 hours of signing.

Supply charge

What you pay for the power itself, apart from delivery. For a new system, net metering gives credit for supply charges only.

UCC-1 statement

A public filing a system owner can make to show it owns equipment on your property. A PPA contract must say the owner's right to file a UCC-1 statement. Ask how it works if you sell the home.