Illinois Solar Calculator

Enter your utility and monthly bill — get system size, Illinois Shines SREC income, net metering savings, property tax exemption, and 25-year savings.

Your Illinois solar inputs

Monthly electric bill?

Electric utility?

System size?

Illinois Shines enrollment?

Illinois solar estimate

20 × 400W panels (8 kW system)

Recommended size for your bill: 11.2 kW

Monthly usage1,067 kWh/mo

Annual production (IL 4.0 PSH)9,344 kWh/yr

Annual savings (net metering)$1,402/yr

Illinois Shines SREC annual income$701/yr

Gross system cost$22,400

Federal ITC (30%)-$6,720

Net cost after ITC$15,680

Illinois Shines total (15yr)$10,512

Property tax exemption (20yr est.)$8,960

Payback period7.5 yrs

25-year savings$45,552

Illinois Shines pays ~$0.075/kWh for 15 years. Rate varies by capacity block. Many homeowners receive Illinois Shines as a lump-sum upfront payment — ask your installer about payment options.

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How to Use This Calculator

Enter your bill and select your utility

Illinois has two major regulated utilities for residential solar: ComEd serves northern Illinois including Chicago and its suburbs, while Ameren Illinois covers central and southern Illinois including Springfield and St. Louis suburbs. Your utility determines your electricity rate and net metering credits. Illinois rates ($0.13–$0.15/kWh) are near the national average, but the Illinois Shines SREC program significantly improves solar ROI.

Enable Illinois Shines enrollment

Illinois Shines is the state's Adjustable Block Program (ABP) for solar renewable energy credits (SRECs). It pays solar owners for every kWh of electricity their system generates for a 15-year contract period. The rate varies by capacity block — earlier blocks have higher rates — but typically runs $0.06–$0.09/kWh. Many homeowners receive this as a lump-sum payment upfront through a solar installer, effectively reducing the installed cost before ITC. Ask your installer about payment structure options.

Illinois net metering

Illinois has retail-rate net metering under the Illinois Power Agency Act. Credits accumulate monthly and are reconciled annually. Systems up to 2 MW qualify. The Illinois Commerce Commission oversees net metering rules, which have remained stable and solar-friendly. ComEd and Ameren Illinois customers both qualify.

The Formula

Monthly kWh = Monthly Bill ÷ Electricity Rate Annual Production = System kW × 1000 × 4.0 PSH × 365 × 0.80 efficiency ÷ 1000 Annual Savings = Annual Production × Retail Rate (net metering) Illinois Shines Annual = Annual Production × $0.075/kWh Illinois Shines 15yr Total = Annual × 15 years Gross Cost = System kW × 1000 × $2.80/W ITC Credit = Gross Cost × 30% Property Tax Exemption = Gross Cost × 2.0% × 20 years (est.) Payback = Net Cost ÷ (Annual Savings + Illinois Shines Annual)

Illinois uses 4.0 peak sun hours (PSH) statewide average — Chicago area gets about 4.0 PSH, southern Illinois (Carbondale) gets 4.5 PSH. The $2.80/W installed cost reflects Illinois's competitive solar market. Illinois Shines rate estimated at $0.075/kWh — actual rate depends on capacity block at time of enrollment. Property tax exemption calculated at Illinois's statewide average effective rate of ~2.0%.

Example

Jennifer — Suburban ComEd customer with Illinois Shines

Jennifer is in suburban Chicago (ComEd) paying $160/month at $0.15/kWh. She installs an 8 kW system and enrolls in Illinois Shines.

Monthly bill$160 (ComEd, $0.15/kWh)

System8 kW, Illinois Shines enrolled

LocationSuburban Chicago (4.0 PSH)

Result

Annual production~9,344 kWh/yr

Annual savings (net metering)~$1,402/yr

Illinois Shines annual income~$701/yr

Gross system cost~$22,400

Federal ITC (30%)-$6,720

Net cost after ITC~$15,680

Illinois Shines total (15yr)~$10,512

Payback period~7.5 years

25-year savings~$45,562

Jennifer earns $2,103/year combined from net metering and Illinois Shines, achieving payback under 8 years. Despite Illinois's lower electricity rate versus East Coast states, the Illinois Shines program closes the gap and delivers strong 25-year savings. If Jennifer takes Illinois Shines as a lump-sum payment (~$10,500), her effective net cost drops below $5,200 after ITC — an exceptional deal.

FAQ

What is Illinois Shines and how much does it pay? ▼

Illinois Shines is the state's Adjustable Block Program (ABP) — a production-based solar incentive administered by the Illinois Power Agency. It pays solar owners for every kWh generated for 15 years at a fixed rate determined by capacity block at time of enrollment. Typical rates are $0.06–$0.09/kWh. Many installers offer to purchase your Illinois Shines contract upfront as a lump sum, effectively reducing your installed cost by $8,000–$15,000 before the 30% ITC is applied. If taken as lump sum, the ITC applies to the full gross system cost (not reduced by the lump sum). This can significantly reduce net cost. Check with your installer — some blocks fill quickly.

How does Illinois net metering work? ▼

Illinois has retail-rate net metering under the Illinois Power Agency Act. ComEd and Ameren Illinois customers earn credits at the full retail electricity rate for exported solar. Credits accumulate monthly — in summer you'll generate excess credits that carry forward to offset winter bills. Annually, any remaining credits are cashed out at the "hourly pricing" rate, which is lower than retail. For this reason, it's best to size your system to approximately match your annual consumption, not to create large annual surpluses.

Does Illinois exempt solar from property taxes? ▼

Yes — Illinois law (35 ILCS 200/10-5) exempts solar energy systems from property tax assessment for 20 years. With Illinois's statewide average effective property tax rate around 2%, a $22,000 solar system that would otherwise add $440/year to your tax bill is instead exempt — saving approximately $8,800 over 20 years. Illinois has some of the highest property taxes in the US, making this exemption particularly valuable. The exemption applies automatically once your system is installed and permitted.

Is solar worth it in Chicago with less sun than other states? ▼

Yes — Chicago gets about 4.0 peak sun hours, which is lower than sunbelt states (5–6 PSH) but enough for solar to be economically strong. The key factor is Illinois Shines, which effectively pays you for every kWh regardless of sunshine variability. Additionally, Illinois's 30% federal ITC, property tax exemption, and retail net metering combine to create payback periods of 7–10 years — comparable to sunbelt states despite the lower PSH. Roof orientation matters more in Chicago: south-facing systems at the optimal tilt outperform flat or east/west orientations significantly.

What is the difference between ComEd and Ameren Illinois solar programs? ▼

Both ComEd (northern IL) and Ameren Illinois (central/southern IL) offer net metering and Illinois Shines enrollment. The main differences: ComEd has a higher electricity rate ($0.15/kWh) meaning more net metering savings per kWh, and serves denser urban/suburban areas with potentially more installer competition. Ameren Illinois has a slightly lower rate ($0.13/kWh) but southern Illinois gets more sunshine (up to 4.5 PSH vs. 4.0 PSH in Chicago). Both utilities offer the same Illinois Shines SREC rate — the program is state-administered, not utility-specific. Downstate Ameren customers often get more production per dollar invested due to better sunshine.

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