FEOC Rules for Solar Installers: Supplier Checklist for 2026

Last updated: July 7, 2026. FEOC guidance is still evolving. Treasury is required to publish additional safe harbor tables by December 31, 2026.

FEOC rules for solar installers are reshaping how equipment gets sourced for federal solar tax credits. The One Big Beautiful Bill Act added new prohibited foreign entity restrictions to clean energy credits. IRS Notice 2026-15 gave installers, suppliers, and TPO partners an interim framework for calculating material assistance.

A sourcing issue can cost a project its 48E tax credit before a single panel goes up. For TPO, lease and PPA, light commercial, and storage projects, the key question is whether the system includes too much material assistance from a prohibited foreign entity, or PFE. That question gets answered through a formula called the material assistance cost ratio, or MACR, and it now sits at the center of solar equipment sourcing rules for 2026.

This guide breaks down what FEOC actually means and gives you a practical checklist for suppliers and financing partners.

Why FEOC Rules Matter to Solar Installers in 2026

Installers may hear these called FEOC rules, but the tax credit language itself focuses on prohibited foreign entities, or PFEs. The clean energy provisions in the OBBBA added material assistance restrictions for projects claiming credits under Section 48E, Section 45Y, and Section 45X. That covers more than utility-scale developers.

Projects affected include:

• TPO-owned residential systems

• Leased and PPA projects

• Light commercial systems claiming 48E

• Battery storage projects

Cash-sale residential installers may not be the taxpayer claiming 48E. The same modules, inverters, batteries, and documentation still matter. TPO partners, lease and PPA providers, commercial customers, and future supplier requirements can all be affected.

What to Ask Your Suppliers Before Equipment Is Selected

Supplier documentation is where most 48E FEOC compliance problems start. Notice 2026-15 gives taxpayers interim ways to calculate material assistance, including identification and cost-percentage safe harbors, plus a certification safe harbor for supplier documentation. That certification has to meet specific requirements, so it helps to know what a compliant one looks like before you request it.

Run through this checklist with any equipment supplier:

• Is this product manufactured, produced, or assembled by a prohibited foreign entity?

• Are any key components sourced from a PFE?

• Can you provide a signed supplier certification with the required identification number and penalties-of-perjury language?

• Which safe harbor does it rely on, Identification or Cost Percentage?

• Will you retain the certification for at least six years? Both supplier and taxpayer are required to.

• Does it cover the equipment and listed manufactured product components used in this project, including modules, inverters, batteries, and any applicable racking or balance-of-system items?

• Does it apply to this specific product model, SKU, purchase order, or project, rather than a blanket company-wide claim?

A taxpayer cannot rely on a certification it knows, or has reason to know, is inaccurate. Good faith reliance on paperwork only protects you if the paperwork actually holds up.

What to Ask Your TPO or Financing Partner

Many installers will not personally calculate the MACR. That work usually falls to the TPO provider or the entity claiming the tax credit. But installers are often the ones selecting equipment, substituting products, and passing documentation upstream.

• Are you requiring a specific approved equipment list for FEOC or PFE compliance?

• Who collects and holds the supplier certifications, you or us?

• Do we need to preserve purchase orders, spec sheets, or distributor documentation on our end?

• Can equipment substitutions after contract signing create credit eligibility issues?

• Are batteries, inverters, racking, and interconnection equipment reviewed separately from the modules?

What FEOC and PFE Mean in Plain English

Prohibited foreign entity solar equipment generally falls into one of two categories:

• A specified foreign entity: a company or government tied to China, Russia, Iran, or North Korea

• A foreign-influenced entity: a company with disqualifying ownership, control, or debt ties to a specified foreign entity

Norton Rose Fulbright's breakdown of the law describes this as a three-part test. Is the taxpayer itself a PFE? Does the project receive material assistance from a PFE? Does a contract give a PFE effective control over the project?

The ownership math gets detailed fast, including single-owner and aggregate ownership thresholds plus a debt attribution test. It is worth reviewing with a tax advisor if your supply chain touches any of these categories.

The Material Assistance Cost Ratio Explained Without the Tax Jargon

The material assistance cost ratio, or MACR, is the actual math behind FEOC compliance. The formula looks intimidating in the statute, but the concept is simple:

MACR = (total direct costs minus PFE-sourced direct costs) ÷ total direct costs

The higher the ratio, the less a project depends on PFE-sourced components. One worked example puts it simply: if total direct costs are $1,000 and $375 comes from PFE-sourced items, the MACR is 62.5 percent.

MACR Thresholds for Solar and Storage

Thresholds vary depending on what is being built and when construction begins. Bracewell's threshold breakdown lines up with the numbers below, drawn directly from Notice 2026-15.

• Qualified facilities (48E or 45Y): 40 percent for construction beginning in 2026, rising 5 points a year to 60 percent by 2029

• Energy storage technology: 55 percent for construction beginning in 2026

• Eligible components under Section 45X, a separate manufacturing credit: 50 percent for certain solar components sold in 2026

What Does and Doesn't Count Toward the Ratio

Not every material in a project counts toward the MACR the same way. Steel and iron construction materials that are structural in function generally fall outside the calculation, unless they are specifically identified as a manufactured product or component. Other materials should be checked against the applicable IRS tables and your own supplier documentation rather than assumed.

Interconnection Equipment Needs Its Own Compliance Check

Qualified interconnection property may need its own MACR calculation, separate from the rest of the project, if those costs are being included in the qualified investment. This is one of the more useful nuances for installers who handle utility interconnection paperwork.

A low or uncalculated interconnection MACR does not disqualify the underlying facility's 48E credit. It just means those interconnection costs may need to be left out of the qualified investment. The reverse is not true. If the facility itself fails its MACR, the interconnection property fails too.

Not sure whether a project needs a separate interconnection MACR calculation? GreenLancer's engineering team can help sort out plan sets and documentation before it becomes a bigger problem.

FEOC vs. Domestic Content: Related, But Not the Same

Installers often confuse FEOC compliance with the domestic content bonus credit. They are related, but they answer different questions.

• Domestic content determines whether a project qualifies for a bonus credit rate

• FEOC and PFE material assistance rules determine whether a project qualifies for the underlying credit at all

Both frameworks currently lean on the same domestic content safe harbor tables, which is part of why the two get confused. Foley Hoag's analysis confirms they still serve separate purposes and require separate reviews.

What Happens If a Project Fails the MACR Test

A failed MACR does not sink a company. It sinks a specific project, facility, storage system, or component.

• The credit gets disallowed for that specific item, not every project the company has ever installed

• The IRS can assess a deficiency tied to a material assistance error within six years of when the return was filed

• Accuracy-related penalties can apply, and MACR errors may face a lower threshold for being treated as a substantial underpayment

• Suppliers who knowingly or negligently provide false certifications can face a separate penalty, generally the greater of 10 percent of the resulting underpayment or $5,000, unless they can show reasonable cause

Some parts of PFE status determination are still unsettled. McGuireWoods flags several open questions that Treasury has not yet addressed in follow-up guidance.

How This Fits Into Your Project Timeline

FEOC compliance is not a paperwork step you handle after the sale. It needs to start when you are selecting equipment, right alongside safe harbor and beginning-of-construction planning.

Sourcing decisions made now affect credit eligibility later. Waiting until after contract signing to sort out supplier documentation creates unnecessary risk. SEIA's most recent industry outlook confirms the picture is still developing. Additional guidance is still expected, so treat today's interim rules as the baseline rather than the final word.

FAQ on FEOC Rules for Solar Installers

What is a prohibited foreign entity in solar?

A prohibited foreign entity, or PFE, is either a specified foreign entity tied to China, Russia, Iran, or North Korea, or a foreign-influenced entity with disqualifying ownership, control, or debt ties to one of those. This PFE status is what determines whether prohibited foreign entity solar equipment disqualifies a project from claiming credits under Section 48E, 45Y, or 45X.

Do residential installers need to worry about FEOC?

Cash-sale installers are usually not the taxpayer claiming 48E, but the same equipment and documentation often affect their TPO partners, lease and PPA providers, and commercial customers. Even a cash-sale business can get pulled into 48E FEOC compliance questions if a supplier's paperwork changes or a distributor drops a product line.

How much PFE-sourced equipment can a 48E project include in 2026?

Non-PFE content needs to make up at least 40 percent of total direct costs for a qualified facility in 2026, and at least 55 percent for storage. That does not mean installers should treat the remaining percentage as a safe allowance. The calculation depends on direct costs, supplier status, and the applicable IRS tables, and these thresholds are set by the material assistance cost ratio itself, which climbs every year through 2029.

Is FEOC compliance based on country of origin or supplier status?

It is based on the status of the entity that mined, produced, or manufactured the component, not simply the country where it was assembled or shipped from. That distinction matters for solar equipment sourcing rules in 2026, since a product assembled domestically can still fail the test if a prohibited foreign entity produced a key underlying material.

How do I verify a supplier is FEOC compliant?

Request a signed certification that includes the supplier's identification number, is signed under penalties of perjury, and states whether the product was produced or manufactured by a PFE. Use the supplier checklist above as a starting point, and treat solar supplier documentation requirements as part of your standard intake process for every new equipment line, not a one-time check.

Does FEOC affect leased or TPO systems?

Yes. TPO providers claim the 48E credit directly, so their equipment sourcing is subject to the same material assistance rules as any other qualified facility. If you sell or install for a TPO partner, ask directly how they are handling 48E FEOC compliance before you commit to a supplier.

How is FEOC different from domestic content?

Domestic content affects whether a project earns a bonus credit rate. FEOC and PFE material assistance rules affect whether a project qualifies for the credit at all. Both frameworks reference some of the same domestic content safe harbor tables, which is exactly why the two get mixed up so often.

Bottom Line

GreenLancer is not a tax advisor, but our solar design, engineering, interconnection, and plan set teams help installers keep project documentation organized before sourcing decisions turn into permitting, financing, or closeout problems.

This is not tax advice. FEOC guidance is still evolving, and Treasury is expected to publish additional safe harbor tables by December 31, 2026. Confirm specifics with a tax or accounting professional before making sourcing decisions, firms like Grant Thornton publish ongoing updates as guidance develops.