The commercial solar Investment Tax Credit is still 30 percent in 2026. The credit that ended was the residential one. Any commercial or industrial project that begins construction by July 4, 2026 locks in the full 30 percent under Section 48E, plus a 10 percent Energy Community bonus where the facility qualifies, and then has until the end of 2030 to be placed in service under the IRS continuity safe harbor. This guide walks through what the deadline requires, how a commercial project begins construction, what the credit is worth once depreciation is added, and the Illinois incentives that apply on top.
Fast Facts
- Program: Federal Commercial Solar Investment Tax Credit (Section 48E), with the begin-construction safe harbor.
- Authority: Internal Revenue Code Section 48E. Begin-construction rules and the 1.5 MW AC threshold under IRS Notice 2025-42.
- What it is worth: 30 percent of total system cost. 40 percent in a qualifying Energy Community. Transferable for cash under Section 6418.
- Who qualifies: Any commercial or industrial taxpayer that begins construction by July 4, 2026.
- Begin construction by: July 4, 2026.
- Place in service by: End of 2030 under the continuity safe harbor. Projects that begin after July 4, 2026 must be in service by December 31, 2027.
- Stacks with: Illinois Shines SRECs, the ComEd or Ameren rebate at $250 per kW DC, and MACRS bonus depreciation. Each captured individually.
- Primary sources: IRC Section 48E, IRS Notice 2025-42.
- 1 The 30 percent commercial solar credit is alive. The residential credit (Section 25D) is the one that ended after 2025. Do not let headlines about the residential credit decide a commercial project.
- 2 July 4, 2026 is a begin-construction deadline, not a finish-the-project deadline. A project that begins construction by then preserves the 30 percent credit vintage and has until the end of 2030 to be energized.
- 3 Beginning construction does not commit you to building. It commits a defined cost or a defined scope of physical work, and preserves the credit while the financing and build decisions get made.
- 4 On a taxable commercial project in a qualifying Energy Community, the 40 percent federal credit and 100 percent bonus depreciation recover roughly 57 percent of project cost in year one. Without the Energy Community bonus, the 30 percent credit and depreciation recover about half. Illinois Shines and the ComEd or Ameren rebate apply on top, each on its own timeline. The Illinois detail lives on the Incentives & Safe Harbor pillar.
The four-click read
Four things to know before July 4, 2026
The whole decision in four cards. Each links to the section that proves it.
What to lock before July 4
Begin construction by July 4, 2026 to preserve the full 30 percent credit vintage. For systems at or below 1.5 MW AC, the 5 percent cost method is the clean path.
How it worksWhat changes July 5
Miss the deadline and the project must be placed in service by December 31, 2027, sourcing rules tighten, and a 500 kW project's post-tax cost rises roughly 25 to 40 percent.
After the deadlineThe 1.5 MW AC line
IRS Notice 2025-42 keeps the simple 5 percent method for systems at or below 1.5 MW AC. GEC engineers the AC nameplate to sit under it on purpose.
The thresholdWhat the credit is worth
In a qualifying Energy Community, the 40 percent federal credit plus 100 percent bonus depreciation recovers about 57 percent of project cost in year one, before any Illinois incentive. At the base 30 percent credit, the figure is about half.
What it's worthWhy the date matters
July 4, 2026 is the federal begin-construction deadline to lock in the full 30 percent commercial solar ITC under Section 48E. A project that begins construction by then has until the end of 2030 to be placed in service. After the deadline, the federal credit changes shape and foreign-entity sourcing rules tighten, raising total project cost for projects that have not begun construction. The realistic path from a cold start to a defensible begin-construction position runs about four weeks, so the practical window is shorter than the calendar suggests.
Does the commercial solar tax credit still exist in 2026?
Yes. The commercial and industrial solar credit under Section 48E is still 30 percent for projects that begin construction by July 4, 2026. The credit that ended is the residential one, Section 25D, which applied to homeowners and was terminated for systems placed in service after 2025. These are two different credits in two different parts of the tax code, and the headlines about the residential credit ending do not apply to a business installing solar on its own facility.
This is the single most common point of confusion in 2026, and it costs commercial owners real money when they assume the window has closed. For a manufacturer, distributor, or commercial property owner, the federal credit is intact at 30 percent, the 10 percent Energy Community bonus is available where the facility address qualifies, and the path to securing both runs through the begin-construction deadline below, not through anything that happened to the residential credit.
Is July 4, 2026 a deadline to finish or to begin construction?
July 4, 2026 is a begin-construction deadline. It is not the date the system has to be installed, energized, or paid off. A commercial project that begins construction by that date preserves the 30 percent credit vintage in effect today, and then has until the end of 2030 to be placed in service under the IRS continuity safe harbor while keeping that credit. Begin construction now, build on a sensible timeline later.
That distinction is what makes the deadline workable. The work that genuinely has to happen by July 4 is narrow. The work that can happen across the build window that follows is everything else: final financing structure, landlord consent on a leased facility, interconnection studies with ComEd or Ameren, equipment procurement, and construction itself.
How does a commercial project begin construction?
The IRS recognizes two ways to begin construction for solar ITC purposes. A project needs to satisfy one of them by the deadline and then maintain continuous progress toward completion. GEC handles component sourcing and the prevailing-wage and apprenticeship compliance the bonus credits require, so eligibility is captured cleanly rather than lost on a technicality.
The 5 percent cost method
A taxpayer can begin construction by paying or incurring at least 5 percent of total project cost before the deadline, under a binding written contract. For a 500 kW commercial system priced around $1,000,000, that is roughly $50,000. Vague intent does not qualify. An invoiced deposit or purchase order on modules, inverters, or racking that crosses the threshold does. Under IRS Notice 2025-42, the 5 percent method is available to systems at or below the 1.5 MW AC low-output threshold. That covers most commercial rooftop and ground-mount projects, and GEC engineers the system AC nameplate to sit at or below that line on purpose, because it is the cleaner, lower-friction path to lock in the credit.
The physical work test
Alternatively, a taxpayer can begin physical work of a significant nature before the deadline: custom fabrication of project equipment under a binding written contract, structural racking installation, or the start of switchgear and transformer work. The threshold is qualitative rather than a dollar figure, and the IRS expects documented continuous progress from that point. This is the path for systems above 1.5 MW AC, where the 5 percent method no longer applies.
The two begin-construction methods compared
| Method | What it requires | Best fit | Documentation |
|---|---|---|---|
| 5% cost method | Pay or incur 5% of total project cost under a binding contract | Systems at or below 1.5 MW AC (most commercial projects) | Invoices, purchase orders, binding contract |
| Physical work test | Begin physical work of a significant nature, then continuous progress | Systems above 1.5 MW AC | Fabrication contracts, engineering records, build logs |
IRS Notice 2025-42 sets a 1.5 MW AC low-output threshold. At or below it, the simpler 5 percent cost method applies. GEC engineers every commercial system to sit at or below that line on purpose, so its projects stay on the clean 5 percent path to the credit and never depend on the physical work test.
Beginning construction is not the same as signing a construction contract and breaking ground on the full system. It does not commit the owner to building. It commits a defined cost or a defined scope of physical work, preserves the federal credit vintage, and opens the build window to decide whether and how to proceed.
What is the 30 percent worth once you add depreciation?
For a taxable business, the headline 30 percent is only part of the recovery. The system basis is also eligible for 100 percent first-year bonus depreciation under current law, which recovers an additional portion of project cost for owners with the tax position to use it. Combined, the federal credit and first-year depreciation recover about half of project cost on a typical commercial project, before any state or utility incentive. In a qualifying Energy Community, where the federal credit rises to 40 percent, that first-year recovery reaches roughly 57 percent. The detailed payback math, including demand-charge savings, is modeled per project. The table below shows the federal credit at representative Illinois manufacturer scale.
Representative federal economics for Illinois commercial solar (2026 pricing)
| System Size | Typical Project Cost | 30% Federal ITC | 5% Begin-Construction Figure |
|---|---|---|---|
| 200 kW rooftop | ~$400,000 | ~$120,000 | ~$20,000 |
| 500 kW rooftop | ~$1,000,000 | ~$300,000 | ~$50,000 |
| 1 MW rooftop or ground | ~$2,000,000 | ~$600,000 | ~$100,000 |
| 2 MW rooftop or ground | ~$4,000,000 | ~$1,200,000 | ~$200,000 |
Representative figures only. Actual project cost depends on roof type, electrical infrastructure, and whether storage is integrated, and the bonus depreciation benefit depends on the owner being a taxable business with the appetite to use it. The credit is also transferable to third-party buyers under Section 6418 if the owner cannot use it directly.
Which Illinois incentives apply on top of the federal credit?
Illinois is where the federal credit goes from strong to decisive, because several state and utility programs apply on top of it. For an Illinois commercial or industrial facility, the package usually includes:
- The 10 percent Energy Community bonus. Added to the 30 percent federal credit where the facility address sits in an IRS-designated Energy Community census tract. Many Illinois industrial corridors qualify, verified at the address.
- Illinois Shines SRECs. Fifteen years of Solar Renewable Energy Credit revenue through Illinois Shines, paid out over the first several years of the contract rather than as a single lump sum. Registration timing matters because the program fills in blocks.
- The ComEd or Ameren distributed generation rebate. Most of Illinois is served by ComEd in the north or Ameren downstate, and both pay the same distributed generation (smart inverter) rebate of $250 per kW DC of installed solar, roughly 10 percent of total project cost, as a direct cash check after commissioning. A 1 MW system earns a $250,000 check. See the ComEd rebate and the Ameren Illinois rebate.
- MACRS and bonus depreciation. Accelerated cost recovery for taxable businesses, applied to the system basis on top of the credit and the rebate.
None of these apply automatically. Each is verified at the project and address level, and the real economics depend on the verified package, not the theoretical maximum. The full program detail, including who qualifies and what each one pays, is worked out on the Incentives & Safe Harbor pillar.
GEC does not outsource engineering. The incentive figures in your proposal come from the same licensed engineers who design and build the system, so the numbers you see are the numbers GEC backs. Final incentive capture depends on your tax position and program availability at the time of filing.
Find Out What Your Facility Qualifies For
Send one recent utility bill per meter and your facility address. GEC verifies Energy Community status, identifies the federal and Illinois programs that apply, and returns an indicative system design with a per-incentive projection, usually within a week. No commitment to move forward.
Is it too late to begin construction in time?
For most Illinois commercial facilities, no, but the runway is real and the work has to start now. The realistic path from a first conversation to a defensible begin-construction position runs about four weeks: a site visit and utility-bill review, an engineering assessment, a decision meeting with the owner and finance, then the begin-construction commitment itself. The detailed week-by-week version, written for a 100 to 500 employee manufacturer, is in the Illinois manufacturer decision guide.
The reason to start now is not the calendar alone. It is that the begin-construction commitment is the only piece bound to July 4. Everything heavier (final financing, leased-facility consent, interconnection, procurement, construction) happens across the build window that follows, which runs to the end of 2030, on the owner's timeline rather than the credit's.
What changes on July 5, 2026?
The federal credit does not vanish on July 5. It changes shape, and the change runs against the project. A commercial project that has not begun construction by the deadline faces a combination of cost increases and incentive risk:
- A hard placed-in-service backstop. A project that begins construction after July 4, 2026 must be placed in service by December 31, 2027 to claim the credit, a much tighter window than the end-of-2030 safe harbor available to projects that begin in time.
- Tighter foreign-entity sourcing rules that raise total project cost roughly 15 to 20 percent where components come from restricted suppliers, which GEC manages through procurement (a GEC-modeled estimate).
- Exposure to the Illinois Shines program moving to a lower-paying block, since registration timing is not guaranteed at current rates indefinitely.
- Continued exposure to rising ComEd and Ameren demand and capacity charges, with no on-site mitigation in place yet.
On a representative 500 kW Illinois project, the net effect is a 25 to 40 percent increase in total post-tax project cost for a project that misses the deadline versus one that locks the credit in beforehand. The capacity-charge pressure driving the last point is its own subject, covered in the Illinois Energy Market hub.
How to begin construction before the deadline
The realistic sequence for a commercial facility that has not started yet:
- 1 Share 12 months of utility bills and the facility address. Two inputs are enough to verify Energy Community status, identify the applicable programs, and size a preliminary system.
- 2 Get the engineering assessment. Structural review, interconnection feasibility, indicative system design, project cost estimate, and modeled incentive capture across the federal credit, the Energy Community bonus, Illinois Shines, the utility rebate, and depreciation.
- 3 Hold the decision meeting. Owner, operations, and finance review the assessment together and choose a financing structure: cash, capital lease, operating lease, PPA, or credit transfer under Section 6418.
- 4 Choose the begin-construction method. The engineering team confirms the 5 percent cost method for the system, which is engineered at or below 1.5 MW AC, and documents it properly.
- 5 Make the begin-construction commitment by July 4. Meet the chosen threshold under a binding contract. From that point, the project preserves the 2026 credit vintage and moves to the build window, with placement in service available through the end of 2030.
How GEC captures safe harbor for your facility
GEC captures the safe harbor as a service. You send one recent utility bill per meter and your facility address. GEC verifies Energy Community status, models the full incentive set against your roof and load inside a week, and structures the begin-construction commitment on the clean 5 percent path. For strong projects, GEC funds the safe harbor through a letter of intent.
- 1 Send two inputs. One recent utility bill per meter and the facility address. That is enough to verify Energy Community status, identify every program that applies, and size a preliminary system.
- 2 Get the model in a week. GEC's licensed engineers model the federal credit, the Energy Community bonus, Illinois Shines, the ComEd or Ameren rebate, and depreciation against your specific roof, load profile, and utility territory. Engineering, procurement, and construction sit under one roof, so the numbers come from the team that builds the system.
- 3 Hold the decision meeting. Owner, operations, and finance review the model and choose a structure: cash, lease, PPA, or credit transfer under Section 6418.
- 4 Lock the credit on the clean path. GEC sizes the system at or below 1.5 MW AC and structures the begin-construction commitment on the 5 percent cost method, the simpler safe harbor under IRS Notice 2025-42.
- 5 The LOI does the work. For strong projects, GEC funds the safe harbor through a letter of intent. That preserves the 2026 credit vintage and the July 4 deadline without committing you to build. You keep the option and the timeline.
The site assessment is free, and there is no commitment to move forward.
A real Illinois result: Core Pipe Products
Core Pipe Products is an Illinois manufacturer in Carol Stream that worked with General Energy Corporation on an 802 kW rooftop solar installation. The system offsets roughly 90 percent of the facility's electricity use and generates more than $76,000 in annual savings. Carol Stream sits in a confirmed Energy Community zone, so the project captured the 10 percent bonus on top of the 30 percent base credit. Before committing, the company's CEO had his CPA independently verify every number GEC presented. The numbers held. Project economics vary site to site, but they are specific, verifiable, and not theoretical.
Frequently Asked Questions
Start Before the July 4 Window Closes
The realistic path from first conversation to a defensible begin-construction position is about four weeks. Start week one today by sharing 12 months of utility bills and your facility address. Personal reply within one business day, and no commitment to move forward.
This guide is general information, not tax or legal advice. Federal and Illinois incentive values depend on project specifics, the owner's tax position, program availability at the time of application, and current law, all of which can change. Confirm eligibility and figures with your tax advisor and against the primary sources linked here before acting.
Continue the series
- Up to the hub: Incentives & Safe Harbor, the pillar that ties every Illinois program together.
- The Illinois-manufacturer decision guide: Safe harbor for Illinois manufacturers in 2026, the week-by-week version for 100 to 500 employee plants.
- Why costs are climbing: Illinois Energy Market, the PJM capacity and rate context behind the urgency.
- Sibling monographs (planned): the Energy Community 10% bonus, Illinois Shines SRECs, and the ComEd and Ameren DG rebate.
References
- 1 IRC Section 48E (commercial clean electricity investment credit). law.cornell.edu/uscode/text/26/48E
- 2 IRC Section 6418 (transferability of credits). law.cornell.edu/uscode/text/26/6418
- 3 IRS Notice 2025-42 (beginning of construction, 1.5 MW AC threshold). irs.gov/pub/irs-drop/n-25-42.pdf
- 4 IRS, One Big Beautiful Bill provisions. irs.gov/newsroom/one-big-beautiful-bill-provisions
- 5 DOE, Guide to the Federal Investment Tax Credit for Commercial Solar PV. energy.gov (PDF)
- 6 SEIA, Depreciation of Solar Energy Property (MACRS). seia.org/depreciation-solar-energy-property-macrs
- 7 Illinois Shines. illinoisshines.com
- 8 ComEd Distributed Generation rebate. comed.com/smart-energy/.../solar-rebates
- 9 Ameren Illinois renewables and solar. ameren.com/service/renewables/solar
- 10 DSIRE, ComEd Distributed Generation and Storage Rebates. programs.dsireusa.org (DSIRE)
