Solar Answers → Buying & Financing
How much do solar panels cost in Illinois?
The Illinois Power Agency — the state agency that sets Illinois Shines REC prices — models residential solar at $3.73 per DC watt in ComEd territory and $3.66 in Ameren territory for 2026. That is about $37,300 for a 10 kW system before incentives. National comparison sites publish $2.81 to $3.15 for Illinois, roughly 20% lower. Neither figure is a quote for your roof.
If you have collected two or three quotes and they do not agree with each other — or with anything you have read online — you are not missing something obvious. The numbers published for Illinois come from different kinds of data, and most of them are not measuring what you probably think they are measuring. This page shows you which is which, and where a quote in your hand actually sits.
Independent public sources we cite and link — The Day Company is not affiliated with or endorsed by any of them.
How much do solar panels cost in Illinois in 2026?
Illinois publishes its own answer, and almost nobody quotes it. In Appendix D to its 2026 Long-Term Renewable Resources Procurement Plan, the Illinois Power Agency models a representative residential system at $3,734 per DC kilowatt in ComEd territory and $3,657 per DC kilowatt in Ameren territory, in 2026 dollars. That is the cost basis the state uses to calculate what your Illinois Shines RECs are worth — which means Illinois has already decided what it thinks solar costs here, and the figure is higher than anything you will find on a comparison site.
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| Reference point | Figure | What the number is | As of |
|---|---|---|---|
| Illinois Power Agency — ComEd territory (Group B) | $3.734/W | Modeled cost basis for a representative residential system | 2026 Long-Term Plan (Oct 2025) |
| Illinois Power Agency — Ameren territory (Group A) | $3.657/W | Same model, lower labor assumption | 2026 Long-Term Plan (Oct 2025) |
| Berkeley Lab — U.S. residential median | $4.00/W | Reported prices actually paid, before incentives | 2024 installs |
| Berkeley Lab — U.S. 20th–80th percentile | $3.00 – $5.20/W | The band most systems fall inside | 2024 installs |
| Berkeley Lab — Illinois | Not published | Too few usable Illinois price records to report | 2016 – 2024 |
The Agency's figures are stated per DC watt. A quote's headline "system size" may be a DC or an AC rating, and the two are not interchangeable — which is one reason two quotes for what sounds like the same system can price very differently. Ask which rating a quote uses before comparing it to anything on this page.
Two things follow from that table. The state's own number sits above every figure commonly published for Illinois, and it sits inside Berkeley Lab's national band rather than at the bottom of it. And the one organization that tracks what people actually paid has no Illinois figure to give at all.
What does that come to for a whole system?
Multiplying the state's per-watt figure by common DC system sizes gives the totals below, before any incentives. These are arithmetic on a published number, not quotes and not estimates for any particular home — but they are the figures the State of Illinois is working from, and they run roughly 20 to 24% above the totals most comparison sites publish for the same sizes.
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| System size (DC) | Ameren territory | ComEd territory | Commonly published elsewhere |
|---|---|---|---|
| 6 kW | $21,942 | $22,404 | ~$18,000 |
| 8 kW | $29,256 | $29,872 | ~$24,100 |
| 10 kW | $36,570 | $37,340 | ~$30,100 |
| 12 kW | $43,884 | $44,808 | ~$37,800 (at 12.5 kW) |
Left two columns: Illinois Power Agency modeled cost basis ($3,657/kW Group A, $3,734/kW Group B, 2026 dollars) multiplied by DC system size. Right column: the range of totals published for Illinois across national comparison and review sites at these sizes, as surveyed August 3, 2026 and rounded — we do not republish or endorse any single site's figure. Gross figures before incentives, excluding batteries.
If your quote is closer to the right-hand column than the left, that is not automatically good news or bad news — it may mean a competitive installer, a simple roof, or a smaller scope than the state's model assumes. It is worth understanding rather than assuming.
What are you actually paying for?
Hardware is the smaller half, which surprises most people. The Agency breaks its Illinois modeling into four line items, and the equipment — modules and inverters together — accounts for roughly a third of the total. Berkeley Lab reaches the same conclusion from the other direction: soft costs and other balance-of-system costs make up about 80% of the installed price of a residential system.
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| Cost component | Ameren territory | ComEd territory |
|---|---|---|
| Generation equipment — modules and inverters | $1,236/kW | $1,236/kW |
| Balance of plant — racking, wiring, structural and electrical work, fieldwork labor | $1,081/kW | $1,158/kW |
| Interconnection | $158/kW | $158/kW |
| Development costs and fee | $1,182/kW | $1,182/kW |
| Total | $3,657/kW | $3,734/kW |
Illinois Power Agency, Appendix D to the 2026 Long-Term Plan, Table D-2. Figures in 2026 dollars per DC kilowatt. Note the equipment line is identical statewide — the entire ComEd-versus-Ameren gap sits in labor.
One line does not reconcile, and we would rather say so than paper over it. ComEd's application fee for a Level 1 interconnection — the track a residential solar system uses — is $50, and Illinois rules cap what a customer can be charged for the whole Level 1 process at $200. The Agency's modeled interconnection line is considerably larger than either figure on any residential system size.
Worth being precise about, because it is widely reported wrong: the Illinois Commerce Commission's interconnection rules set the Level 1 application fee at $50 and cap the customer's total Level 1 cost at $200, with anything above that recovered through delivery rates. The Illinois Power Agency's Appendix D attributes the $200 to Section 16-107.5 of the Public Utilities Act, but that statute sets no dollar figure of its own — it delegates fee-setting to the Commission.
Either way, the Plan does not break down why its interconnection line exceeds both numbers, and we are not going to invent an explanation for it. If an installer itemizes interconnection on your quote, ask what the line actually covers.
Why does solar cost more in Illinois than the national average?
Labor, and the Agency says so in plain language. Its model applies a 132% multiplier to Illinois construction wages relative to the nationwide median. Then it applies a second one: construction labor in ComEd territory runs 130% of the cost of labor in Ameren territory. That is why northern Illinois prices above downstate in the state's own numbers, and it is a structural cost — not a line an installer is padding and not something a harder negotiation will remove.
Two other assumptions in the same model are worth knowing before anyone tells you prices are still falling. The Agency models no net equipment-cost reduction for residential systems between 2022 and 2026 — it carries them at 100% of 2022 costs — while applying 112% inflation over the same period. It also models a substantial tariff-driven increase in the portion of module and balance-of-plant cost that is imported.
The practical version: the cost curve that made solar cheaper every year through the 2010s has flattened, and Illinois sits on the expensive side of a national labor market. A quote that looks high against a number you read on a national site may simply be an Illinois quote.
Why do comparison sites show a lower number?
Because most of them publish quotes, not transactions — and Berkeley Lab says as much about its own comparisons. In its Tracking the Sun report, the lab notes that other published pricing benchmarks align more closely with its 20th percentile than with its median. The 20th percentile is where the cheapest fifth of the market sits. It is a real number, but it is not the typical price, and using it as your yardstick is how a fair Illinois quote starts to look like a rip-off.
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| Where the number comes from | Illinois figure | What kind of data it is |
|---|---|---|
| State of Illinois (Illinois Power Agency) | $3.66 – $3.73/W | Modeled cost basis used to set REC prices |
| National laboratory (Berkeley Lab) | None published since 2015 | Reported transaction prices; third-party-owned systems excluded by design |
| National comparison and review sites | $2.81 – $3.15/W | Quote averages and marketplace data |
Comparison-site range: figures published for Illinois across national solar comparison and review sites, surveyed August 3, 2026. We do not republish or endorse any single site's figure.
Illinois residential solar cost per DC watt, by source. Comparison-site range surveyed August 3, 2026; Illinois Power Agency, 2026 Long-Term Plan, Appendix D Table D-2; Berkeley Lab national residential median, 2024 installs.
The Illinois gap in Berkeley Lab's data is itself informative. The lab suppresses any state-year with fewer than 20 usable price records, and it excludes third-party-owned systems from price analysis entirely — leases and power purchase agreements are not comparable to purchase prices, so they are left out. Berkeley Lab separately identifies Illinois as a state where third-party ownership tends to run higher, driven by the value of the state's incentive programs. The last Illinois residential figure the lab published was for 2015 installs: a median of $5.5/W, with a 20th-to-80th percentile band of $4.7 to $6.6.
None of that makes the lower published figures dishonest. It makes them a different measurement. But if you walk into a sales conversation holding a marketplace average built from the most competitive fifth of a national sample, you are negotiating against a number that does not describe your market — and you will not know which way that cuts until you check.
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Check my eligibility →How much do solar panels cost for a 2,000-square-foot house?
Square footage is the wrong input, and no primary source publishes a cost-per-square-foot rule for solar. What determines your system — and therefore your price — is how many kilowatt-hours you use in a year, how much unshaded roof faces the right direction, and what pitch and roof material you have. Two 2,000-square-foot homes on the same street can need systems that differ by half.
The question is a reasonable one to ask; it just cannot be answered from floor area, and anyone who answers it from floor area is guessing at your bill. Start from your last twelve months of usage instead — that is the input every honest sizing method begins with. Our guide to what size solar system you need in Illinois walks the method, and once you have a system size in kilowatts, the figures on this page will place a quote.
Is the quote I already have in a reasonable range?
Convert it to dollars per watt and place it against published reference points. That is arithmetic, not a verdict — but it takes five seconds, it is how the industry itself compares systems of different sizes, and it is the fastest way to stop wondering whether the number you are holding is normal.
That number is only half the picture. What it does not tell you is whether your roof, your usage and your utility actually support the system it is pricing. The eligibility check is free, takes about a minute, and will tell you if the answer is no.
Check my eligibility →Nothing you type is sent or stored by this page — the math runs entirely in your browser. If you continue to the eligibility check, the figures you entered come with you so you don't have to retype them. This tool compares your figure to published reference points and nothing else: it does not know your roof, your usage, your equipment, your warranty, or your contract terms, and it is not a judgment about whether a quote is fair.
What makes one quote higher than another?
Some of it is measurable, and Berkeley Lab has measured it. Its statistical model of 2023 residential prices estimates how much specific choices moved the price per watt, holding other factors constant. These are national figures for a single year, and the model explains only part of the variation between quotes — but they turn "why is this one more expensive" from a shrug into something you can ask about specifically.
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| What changes | Estimated effect on price per watt |
|---|---|
| Battery storage added | +$1.45/W |
| Ground-mounted instead of roof-mounted | +$0.40/W |
| DC optimizers | +$0.40/W |
| Microinverters | +$0.12/W |
| Each additional kilowatt of system size | −$0.21/W |
| New construction rather than retrofit | −$0.71/W |
Lawrence Berkeley National Laboratory, Tracking the Sun 2024 Edition — regression on 266,903 host-owned residential systems installed in 2023. The model has an R² of 0.12, meaning these factors explain a modest share of overall price variation; treat them as directional, not as a pricing formula. Battery figures here reflect the price of adding storage, not whether storage is worth it.
Two things are worth taking from that table. Bigger systems cost less per watt, so a per-watt comparison between a 6 kW quote and a 12 kW quote is not apples to apples. And a battery is by far the largest single line — if one quote includes storage and another does not, almost the entire difference may be that. Whether the battery earns its place is a separate question, covered in is a home solar battery worth it in Illinois.
What none of it explains is the installer. Berkeley Lab found that among the hundred largest residential installers in 2024, median prices ranged from $2.70 to $6.50 per watt — a spread far wider than any equipment choice above. Who you are talking to moves the number more than what you are buying, which is why the questions on our guide to vetting an Illinois solar quote matter more than any benchmark.
Is it cheaper to buy your own solar panels?
The federal tax code stopped answering that question the same way it used to. The 30% residential clean energy credit that homeowners claimed for buying their own system ended for expenditures after December 31, 2025 — the Illinois Power Agency states this directly in the same Plan the cost figures come from. A separate business-side credit still runs for commercial and third-party-owned projects on its own timeline, with begin-construction and placed-in-service deadlines and sourcing restrictions attached.
That changes the arithmetic rather than settling it, and it is the single biggest reason a 2025 quote and a 2026 quote for the same house can look nothing alike. Buying still carries the $20-per-REC customer-owned adder in Illinois Shines for qualifying systems up to 25 kW that are not claiming the federal credit. Leasing or a power purchase agreement moves the equipment cost off your balance sheet entirely, so "cost per watt" stops being the number that matters and the contract terms start being it. We compare the two paths across the full term in solar lease vs PPA vs buying in Illinois.
What comes off that price in Illinois?
Enough to matter, and it is a longer list than most states have. Illinois Shines pays for the renewable energy credits your system produces — $80.77 per REC in ComEd territory and $70.37 in Ameren territory for systems up to 10 kW in the 2026-27 program year, plus the customer-owned adder where it applies. Both utilities pay a distributed generation rebate. A qualifying system is also excluded from added property tax assessment, though that one requires a filing you have to make yourself.
We are not going to run your net cost on this page, because the timing is the part that trips people up and it deserves its own explanation — REC payments arrive across years, not at closing, and a quote that shows them as an instant discount is telling you something that is not quite true. The full stack, the payment schedule, and what each piece actually requires are on Illinois solar incentives 2026.
One timing note that is genuinely worth knowing: the small distributed generation category has run out of capacity before a program year ended. In the 2024-25 program year, the Agency reports that category's capacity was fully utilized by May 6, 2025. Blocks reopen each program year, but availability across a whole one is not guaranteed.
What is the payback period for solar in Illinois?
There is no defensible single payback figure for Illinois — claims on the first page of search results currently run from about 5.5 years to about 13.4 years for the same state, in the same year, and they cannot all be right. We do not publish one, and there is no way to tell from those pages which claim is closest to your house.
The spread comes from assumptions, not from Illinois: what system size is assumed, what rate escalation is applied, whether REC income is counted at full value or discounted for its payment schedule, and — on several of those pages — whether a federal credit that no longer exists for homeowners is still being subtracted. A payback number is only as good as the assumptions under it, and most pages do not show theirs.
The honest version of the question is whether solar makes sense for your specific bill, roof and usage, which is what is solar worth it in Illinois works through. Your electricity price is also a moving input, not a constant — ComEd's supply rate resets again on October 1, 2026.
Illinois solar cost FAQ
How much do solar panels cost in Illinois in 2026?
The Illinois Power Agency models residential solar at $3,734 per DC kilowatt in ComEd territory and $3,657 in Ameren territory for 2026, in its 2026 Long-Term Plan. That works out to roughly $37,300 for a 10 kW system before incentives. Berkeley Lab's national residential median for 2024 installs was $4.00 per watt, with most systems between $3.00 and $5.20.
Why is the state's figure higher than the ones on comparison sites?
Comparison sites generally publish quote averages rather than prices actually paid. Berkeley Lab notes that other published benchmarks align more closely with its 20th percentile than its median — the 20th percentile being the cheapest fifth of the market. The state's figure is a full cost basis, not a best-case one.
Does solar cost more in Illinois than the national average?
By the state's own modeling, yes. The Illinois Power Agency applies a 132% multiplier to Illinois construction wages relative to the nationwide median, and applies a further 130% multiplier to labor in ComEd territory relative to Ameren territory. Equipment costs are modeled identically statewide.
What makes one Illinois solar quote higher than another?
Berkeley Lab's 2023 model estimates that adding battery storage raises price by about $1.45 per watt, ground-mounting and DC optimizers by about $0.40 each, and microinverters by about $0.12, while each additional kilowatt of size lowers it by about $0.21. Installer choice moves it more than any of those: median prices across the hundred largest residential installers ranged from $2.70 to $6.50 per watt in 2024.
How much do solar panels cost for a 2,000-square-foot house?
Floor area does not determine the answer, and no primary source publishes a cost-per-square-foot rule for solar. System size is driven by annual electricity usage, unshaded roof area, orientation and pitch. Two homes of identical size can need systems that differ by half.
Is the 30% federal solar tax credit still available in 2026?
Not for a homeowner buying their own system. The residential clean energy credit ended for expenditures after December 31, 2025, which the Illinois Power Agency confirms in its 2026 Long-Term Plan. A separate business-side credit still applies to commercial and third-party-owned projects under its own deadlines and sourcing rules.
What does interconnection cost in Illinois?
ComEd charges a $50 application fee for a Level 1 interconnection, which is the track residential solar uses, and Illinois Commerce Commission rules cap a customer's total Level 1 interconnection cost at $200. The Illinois Power Agency's cost model carries an interconnection line item substantially larger than either figure and does not break down the difference, so ask any installer what their interconnection line covers.
Is it cheaper to buy solar panels or lease them in Illinois?
It depends on terms rather than on price per watt. Buying now carries no federal residential credit but can earn the $20-per-REC customer-owned adder in Illinois Shines for qualifying systems up to 25 kW. A lease or power purchase agreement removes the equipment cost entirely and makes the contract terms the number that matters.
Do solar panels increase property taxes in Illinois?
Illinois provides a special assessment that excludes qualifying solar energy systems from added property tax value, but it is not automatic — a filing with your county assessor is required. The details and the form are covered on our Illinois solar incentives page.
What is the payback period for solar in Illinois?
We do not publish one. Illinois payback claims currently in search results range from roughly 5.5 to 13.4 years, a spread driven by differing assumptions about system size, rate escalation, REC payment timing and, on some pages, a federal credit homeowners can no longer claim.
Why does Berkeley Lab have no Illinois cost data?
The lab suppresses any state and year with fewer than 20 usable installed-price records, and it excludes third-party-owned systems from price analysis because lease and power purchase agreement prices are not comparable to purchase prices. Its last published Illinois residential figure was for 2015 installs, at a median of $5.5 per watt.
Related answers
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Sources
- Illinois Power Agency — Appendix D, REC Pricing Model Description, 2026 Long-Term Renewable Resources Procurement Plan (PDF) (October 2025) — Table D-1 and D-2 capital cost inputs, Illinois labor multipliers, interconnection statute reference, federal credit status, Table D-5 REC prices
- Illinois Shines — Program Documents (Illinois Power Agency) — program year 2026-27 REC prices and the REC payment calculator
- Lawrence Berkeley National Laboratory — U.S. Distributed Solar and Storage, 2025 Data Update (PDF) (October 2025) — 2024 national residential median and percentile band, installer-level price range, soft-cost share, price-data methodology
- Lawrence Berkeley National Laboratory — Tracking the Sun, 2024 Edition (PDF) (August 2024) — the pricing-driver regression, comparison to other pricing benchmarks and the 20th-percentile finding, third-party ownership by state
- Lawrence Berkeley National Laboratory — Tracking the Sun data visualization tool — Illinois state-level installed-price series and suppression rule, checked August 3, 2026
- 83 Illinois Administrative Code Part 466 — Illinois Commerce Commission interconnection standards for distributed generation. Appendix A sets the $50 Level 1 application fee; Section 466.90(c) sets the $200 standardized cost for a Level 1 interconnection. Note that the Illinois Power Agency's Appendix D attributes the $200 to 220 ILCS 5/16-107.5, which sets no dollar figure of its own
- National Renewable Energy Laboratory — Q1 2023 Solar Benchmark Cost Report — the underlying component cost data the Illinois Power Agency adjusts for Illinois conditions
How to cite this page: The Day Company, "How much do solar panels cost in Illinois?", theday.company/answers/solar-panel-cost-illinois, last reviewed August 3, 2026.
Changelog: August 2026 — v1 published.
Update triggers: this page is revised when the Illinois Power Agency publishes a new Long-Term Plan or REC price set, and when Berkeley Lab releases its next annual data update.