The federal Investment Tax Credit (ITC) is the single most important financial driver of the US solar market. Understanding how the ITC works, what qualifies, how it interacts with state incentives, and how it applies to commercial versus residential projects is essential for solar EPCs, installers, and developers pricing projects and closing deals. This guide walks through the solar ITC as it stands in 2026, including recent structural changes introduced by the Inflation Reduction Act, direct-pay and transferability options for commercial projects, energy community and domestic content adders, and the storage-specific ITC that has reshaped battery-attached solar economics.
What is the solar investment tax credit (ITC)?
The solar Investment Tax Credit is a federal tax credit that reduces the federal income tax liability of the entity that owns and places a qualifying solar energy system in service. The credit is a percentage of the eligible project cost basis. For residential solar, the credit reduces the homeowner’s personal federal income taxes. For commercial solar, the credit reduces the business’s federal income taxes and is applied against the project’s cost basis in accordance with IRS rules.
The current base ITC rate for qualifying residential and commercial solar projects placed in service is 30 percent, with the possibility of additional adders that increase the effective credit rate substantially for commercial projects meeting specific criteria.
Residential solar ITC (Section 25D)
The residential ITC, codified at Section 25D of the Internal Revenue Code, provides a credit for homeowners who install qualifying solar systems on their primary or secondary residence. Key features:
- Credit is 30 percent of eligible costs for qualifying systems
- Includes solar PV systems, solar water heaters, and battery storage systems with sufficient capacity
- Homeowner must own the system (not leased) to claim the credit
- Credit is non-refundable but can be carried forward to future tax years
- No maximum dollar limit
- Applied against federal income tax liability using IRS Form 5695
Solar EPCs and installers should present residential ITC clearly in customer economic proposals but always recommend customers consult their own tax advisor for their specific situation.
Commercial solar ITC (Section 48 and Section 48E)
The commercial ITC applies to businesses that own qualifying solar and storage systems. It has undergone significant changes with the Inflation Reduction Act, expanding both eligibility and monetization pathways. Base credit is 30 percent for qualifying systems, with additional adders potentially available. The credit applies against federal income tax liability and can be used to offset tax owed.
Energy community adder (+10 percent)
Commercial solar projects located in designated energy communities (former coal, oil, or natural gas communities, and certain brownfield sites) qualify for an additional 10 percent ITC. Determining energy community status requires checking IRS-published maps and geographic criteria for the specific project location. This adder alone can move a project from 30 percent to 40 percent ITC.
Domestic content adder (+10 percent)
Commercial solar projects meeting specific domestic content requirements (US-manufactured steel, iron, and certain manufactured products, per IRS-defined thresholds) qualify for an additional 10 percent ITC. Meeting domestic content requirements affects module and racking selection at the design phase.
Low-income adders (+10 or +20 percent)
Certain smaller solar projects in low-income communities or serving low-income customers may qualify for additional bonus credits (typically 10 or 20 percent depending on the project category), subject to competitive allocation and specific programmatic requirements.
Standalone storage ITC (Section 48E)
The IRA introduced ITC eligibility for standalone battery energy storage systems (ESS), whether or not they are paired with solar. This means storage projects that meet the criteria can claim the ITC independently. When paired with solar, projects can structure to optimize both credits. The design implications for storage sizing, siting, and interconnection are meaningful.
Direct pay and transferability, monetization pathways
Historically, commercial solar tax credits could only be used by entities with sufficient federal tax liability to absorb them, driving the tax equity market. The IRA changed this substantially:
Direct pay (elective payment)
Certain tax-exempt entities (municipal utilities, nonprofits, tribes, state and local governments, and rural electric cooperatives) can elect direct pay, meaning the IRS treats the credit as a payment rather than a tax offset, effectively cash-refunding the credit. This has opened commercial solar to entities that previously had no way to monetize the ITC.
Transferability
Commercial project owners without sufficient tax appetite can now transfer (sell) the credit to unrelated third parties for cash, subject to IRS rules on structuring the transfer. This has created a secondary market for ITC monetization, with transfer discounts typically ranging based on market conditions.
Both direct pay and transferability have broadened who can effectively monetize the solar ITC and reshaped project financing structures. Solar EPCs and developers pricing commercial projects need to understand which monetization pathway applies to a given customer.
Cost basis eligibility
Not every project cost qualifies for ITC. Generally eligible:
- Solar PV modules, inverters, racking, mounting, wiring, and balance-of-system equipment
- Battery storage meeting IRS-defined charging and capacity criteria
- Labor for installation and installation-related equipment
- Certain project development soft costs (permitting, engineering, interconnection where directly tied to the qualifying property)
- Sales tax on eligible equipment
Not eligible: land, structural upgrades unrelated to solar, ongoing operations and maintenance, and various indirect costs. Cost basis determination should always involve a qualified tax professional.
Timing considerations
ITC eligibility depends on when a project is placed in service, which typically means when the system is capable of producing energy for its intended use and has passed final inspection and utility permission-to-operate. Safe harbor rules allow projects to lock in a specific ITC rate by beginning construction (with defined criteria) before certain milestone dates.
For projects that span multiple tax years or where policy changes are anticipated, safe harbor structuring becomes important. Solar EPCs and developers pricing multi-year projects should coordinate with tax counsel on safe harbor documentation.
State incentives stack with the federal ITC
The federal ITC generally stacks with most state and utility incentives, though specific interactions vary:
- State-level ITCs and personal tax credits (in states that offer them) generally stack with federal ITC
- State rebates may reduce the federal ITC cost basis in some cases
- SREC revenue is typically taxable income and does not affect ITC calculation
- Utility rebates may reduce cost basis for ITC purposes
- Property tax exemptions and sales tax exemptions typically do not affect ITC calculation
Every project’s incentive stacking should be reviewed with a qualified tax advisor familiar with both federal and state rules.
How to represent ITC in customer economic proposals
Solar EPCs and installers routinely include ITC in customer proposals. Best practices:
- Present the base 30 percent ITC clearly, with any potentially applicable adders identified
- Always disclose that tax credit realization depends on the customer’s tax situation
- Recommend customers consult their own tax advisor to confirm eligibility and monetization approach
- For commercial projects, discuss direct pay and transferability pathways where applicable
- Document project components in a way that supports cost basis substantiation if audited
What ITC changes could mean for solar plan sets
ITC policy changes affect design in specific ways:
- Domestic content adder eligibility affects module and racking selection
- Storage ITC eligibility encourages ESS-inclusive designs, requiring NEC Article 706 and NFPA 855 coordination in plan sets
- Energy community adder eligibility affects site selection and project qualification documentation
- Safe harbor structuring may drive earlier equipment procurement and design lock-in on multi-year projects
Design teams working closely with commercial solar developers should maintain awareness of these ITC dimensions because they affect equipment specifications and documentation packages.
Where outsourced solar design fits into ITC-optimized projects
ITC monetization, particularly with adders and direct pay/transferability, has increased the design and documentation rigor required for commercial solar projects. Plan sets and equipment specification records need to substantiate ITC claims across multiple dimensions. Outsourced design partners who understand these documentation requirements deliver plan sets that support downstream ITC monetization without rework.
RIH Engineering provides outsourced solar PV design for EPCs, installers, and developers across residential, commercial, and community solar. Our plan sets and documentation packages are prepared with ITC monetization in mind, including domestic content documentation, storage design coordination, and site qualification documentation. If you want to talk through how outsourced design fits your ITC-optimized project pipeline, get in touch.
Frequently asked questions
What is the current solar ITC rate?
The current base federal solar Investment Tax Credit is 30 percent of eligible project cost for qualifying residential and commercial solar systems placed in service. Commercial projects may qualify for additional adders (energy community, domestic content, low-income) that raise the effective credit rate. Always consult a qualified tax advisor for your specific project.
Can commercial solar projects sell their ITC to third parties?
Yes. The Inflation Reduction Act introduced ITC transferability for commercial projects, allowing project owners to sell (transfer) their tax credit to unrelated third parties for cash, subject to IRS rules. This has created a secondary market for ITC monetization and expanded options for developers without sufficient tax appetite to use the credit directly.
What is the energy community ITC adder?
Commercial solar projects located in IRS-designated energy communities (former coal, oil, or natural gas communities, and certain brownfield sites) qualify for an additional 10 percent ITC on top of the base 30 percent, subject to IRS-published geographic criteria. This adder alone can move a project from 30 percent to 40 percent ITC.
Does battery storage qualify for the ITC on its own?
Yes. The Inflation Reduction Act introduced ITC eligibility for standalone battery energy storage systems (Section 48E), meaning storage projects can claim the ITC whether or not they are paired with solar. When paired with solar, projects can structure to optimize both credits. Battery storage must meet IRS-defined charging and capacity criteria.
Do state solar incentives stack with the federal ITC?
Generally yes, though specific interactions vary. State-level ITCs and personal tax credits typically stack with the federal ITC. State rebates and utility rebates may reduce the federal ITC cost basis in some cases. SREC revenue is typically taxable but does not affect ITC calculation. Every project's incentive stacking should be reviewed with a qualified tax advisor familiar with both federal and state rules.