Introduction to Rooftop Solar

Thanks to the rapidly declining cost of solar panels and several incentives, a solar, or photovoltaic (PV) system can be a good financial investment for homeowners. Here are some factors to consider before going solar:

How many panels do I need?

The size and cost of your system largely depends on your annual electricity usage and your property’s sun exposure. Comparing as many solar options as possible can help you avoid paying inflated prices for your system. We recommend getting at least three quotes.

Most solar companies will offer a free off-site quote, where they request your annual electricity usage and look up your property’s solar exposure to give you an estimate without a physical site visit. You can also check out Project Sunroof or PV Watts.

If you use less energy, you’ll need fewer solar panels to account for your electric load. Make sure you’re not using more energy than you need by investing in energy-saving equipment and weatherizing your home. Check with your utility company to see what energy efficiency programs they offer. You may already be paying for such programs on your bill, so you should take advantage of them. Here are more ways to cut your energy use and lower your solar project cost:

Is my roof ready for solar?

If you want to install solar panels on your roof, you’ll need to consider a number of factors, which an installer should assess during an on-site (and possibly paid) evaluation. Your solar installer will walk you through it, but here are a few things to consider:

1. How much of your roof is shaded?

Check out an aerial view of your home on Google Maps. If you can’t see the majority of your roof, you may not get enough sunlight to justify the costs of installing your own system.

2. How old is your roof?

Replacing your roof after installing a solar panel system creates additional costs, and most solar panels are warrantied for 25 years, so if your roof is asphalt singled and over 10 years old, consider roof replacement prior to installing solar panels.

3. Can the size, shape and slope of your roof support solar panels?

A south-facing roof is ideal for solar panels. East and west-facing roofs are okay too but would require 10-20% more panels than a south-facing system, in order to produce the same output. North-facing roofs are not ideal unless the roof is at a very low pitch (5-10 degrees).

4. What type of material is your roof?

Asphalt, tile and metal roofs tend to be an easier surface for installing solar panels. Slate and wood roofs make for more expensive installations.

5. Can you install panels somewhere other than your roof?

If you have open land that gets a lot of sun, a ground mount system could be a good alternative to installing a system on your house.

How will I pay for it?

There are several incentive programs to make solar more affordable:

The Federal Solar Investment Tax Credit: This tax credit deducts a percentage of your solar project costs from your federal income taxes, and now includes credits for system batteries. The credit is 30 percent for the next 10 years, starting Jan 1, 2022. You must own your panels to receive the tax credit. The system must be installed before the end of the year, and you must pay federal taxes to benefit. If the credit amounts to more than you paid in federal taxes in a single year, it can roll over for up to five years. Learn more about the residential energy credit (Form 5695) on the IRS website or on the Solar Energy Industries Association website.

On-bill Credits from your Electric Utility: Once you have installed your system, it’s likely you will not always use 100 percent of the electricity it produces in real time. If your system is connected to your utility’s grid, excess electricity is sent back to the grid and you’ll receive bill credits for that electricity in a process called “net metering.” These credits help maximize your monthly bill savings and ensure you’re credited for every kilowatt-hour (kWh) your system produces, which pays off the remaining cost of your system over time. Net metering also helps cover the cost of the electricity your household uses when your panels are not generating energy, like cloudy days or nighttime. Net metering credits are automatically applied to your utility bill—you will not receive direct payments from your utility company.

Your solar installer will usually take care of the net metering application on your behalf. Ameren, ComEd and MidAmerican are required by state law to offer net metering. These utilities allow unused net metering credits to rollover each month, but they “expire” every year (either April 30th or October 30th, depending on your choice and consumption patterns). If you have a municipal electric utility or cooperative, check their policy.

“Retail” net metering refers to when the customer receives net metering credits on all parts of their bill, including the supply, delivery and taxes and fees sections. The same state law that requires Ameren, ComEd and MidAmerican to offer net metering also allows these utilities to cap how many customers receive retail net metering. Once they reach those caps (5 percent of total peak demand in their service territory), the utilities can restrict future net metering applications so that customers only receive credits on the supply portion of their bill.

Note: Consider your electric supplier before going solar. If you switch suppliers after you’ve built up net metering credits, you will lose them. We’ve also received reports that not all alternative electric suppliers are offering net metering, even though it is required by law. Check your supplier (and cancel if it’s a bad rate) before investing in a solar energy system. If you have the default utility supply, you will be guaranteed the full net metering rate.

Leases and Power Purchase Agreements: Many solar companies advertise leases or Power Purchase Agreements (PPAs) at no upfront cost, where the company pockets the owner incentives, signs the customer up for a long-term contract and may increase the rate over time through contract escalator provisions. With a lease, the customer is charged a fixed amount, usually monthly. With a PPA, the customer is charged for the energy that the panels on their property send to the grid each month. Both arrangements typically allow the customer to buy the system at some point in the contract term, but it depends on the contract, and that’s after the solar company has exhausted the federal and/or state incentives.

Illinois Solar for All: Income qualified customers can get rooftop solar panels at no upfront cost and a guaranteed discount through a state solar incentive program called Illinois Solar for All. Most vendors through Illinois Solar for All require customers to sign up for PPAs, but with the guarantee that they will only ever have to pay for half of what their panels produce. So that means that under Illinois Solar for All, if the panels on your roof produced 800 kWh in a month, you would get utility bill credits for those 800 kWh, but would only have to pay your solar company for 400 kWh.

Eligible participants must meet income eligibility requirements which can be found here. For 2-4 unit residential properties, at least two households must qualify based on income, and for 5+ unit residential properties, at least half of the households must qualify.

Solar Financing: There are many financial resources available to help you pay for your solar investment. Two common types of loans are: bridge loans (covers the period between installing a system and receiving your incentives) and solar loans (offered by banks, credit unions and solar panel manufacturers). Check out A Homeowner’s Guide to Solar Financing from the Clean Energy States Alliance and Solar Financing FAQ from EnergySage.

Solar Renewable Energy Credits: A Solar Renewable Energy Credit, or SREC, is a unit that represents the environmental value of solar power. For every 1,000 kilowatt-hours that your PV system produces, one Solar Renewable Energy Credit is created, which the owner of the PV system can sell to utilities or other companies to help pay for the cost of the system. Your solar installer can provide more information on how to sell your SRECs and will help you determine how much of your project you can expect this incentive to cover.

Battery Storage: Until battery technology gets more affordable and efficient, using solar panels to completely disconnect from the utility’s distribution grid won’t be practical for most households. While it is possible to use batteries to store that excess electricity (instead of sending it back to the grid), integrating battery storage is typically not worth the additional cost. If you choose to keep your solar system entirely “off-grid”—meaning it’s not connected to the power grid—you also wouldn’t be eligible for state solar incentives or net metering.

How do I find solar installers?

If you think rooftop solar would be a good fit for you, contact a few solar installers in your area to get quotes for your project. Find residential solar installers near you by visiting the Illinois Solar Energy Association website.

Can residential solar panel owners participate in “real-time pricing”?

ComEd and Ameren customers with rooftop solar installations can still participate in their utility’s real-time pricing program (“Hourly Pricing” for ComEd, “Power Smart Pricing” for Ameren), but this is only recommended if you own your panels. If you are on a solar lease or Power Purchase Agreement, you will be charged a different rate than what you received in net metering credits on your utility bill. Customers who receive net metering cannot also participate in ComEd’s Peak Time Savings, ComEd’s Time-of-Day Pricing, or Ameren’s Peak Time Rewards.


Solar energy can save you money, but there are some companies that may try to take advantage of solar’s popularity to sign you up for a bad deal, or misrepresent information about state programs.

We do our best at CUB to provide transparent information to consumers, but CUB does not administer either of the state solar programs. If you have questions or concerns about solar, including an advertisement you might have seen or someone who came to your door, you can call the CUB Hotline: 1-800-669-5556, Monday through Friday from 9 am to 4 pm.

You can find complaints regarding solar installers at the Better Business Bureau as well as the Illinois Shines Consumer Complaint Database.

If you believe you have been subject to fraudulent or deceptive sales practices, the Consumer Protection Division of the Illinois Attorney General’s office may be able to help. Customers can contact the following hotlines:

  • Chicago: 1-800-386-5468 (TTY 1-800-964-3013
  • Springfield: 1-800-243-0618 (TTY 1-877-844-5461)
  • Carbondale: 1-800-243-0607 (TTY 1-877-675-9339)
  • Spanish: 1-866-310-8398

How do I learn more?

Check out the Department of Energy’s Homeowner’s Guide to Going Solar and the Solar Energy Industries Association’s Residential Consumer Guide to Solar Power.