12 Questions to Ask a Floating Solar Supplier Before You Buy

Most floating solar purchases go wrong in the same place. An EPC compares two quotes on dollars per watt, takes the cheaper one, and finds out at the water's edge that the kit does not include the mooring design, the shipment is eight weeks out, and nobody can produce the paperwork the tax equity reviewer is asking for. The questions below are the ones that surface those gaps before the purchase order goes out, written for EPCs, installers and developers buying structure for a pond, lagoon or reservoir array.

Why the clock makes this expensive to get wrong

Two deadlines are squeezing floating solar procurement at once.

On the tax side, projects that did not begin construction on or before July 4, 2026 have to be placed in service by December 31, 2027 to claim the Section 48E credit (Olson Partners Law). A supplier who slips eight weeks on a Q3 2027 delivery is not a scheduling nuisance — they can move the project across that line.

On the hardware side, module pricing is still moving. Section 232 minimum import prices take effect December 4, 2026 at $0.22/W for cells and $0.38/W for modules, plus 15% ad valorem on derivative products (Hunton). Separately, the U.S. International Trade Commission issued an affirmative final injury determination on October 14, 2026 covering cells and modules from India, Indonesia and Laos, with Commerce orders due November 2, 2026 (Solar Power World). When the module line of the budget moves, the structure line gets scrutinized. Be ready to defend it.

Questions about the structure itself

1. What is the design basis, and can I see the document? DNV published a recommended practice for floating solar plants, DNV-RP-0584, in 2021 (DNV). Ask which design basis a supplier worked from and ask for the engineering package, not a brochure line. Then check that the wind, wave and ice assumptions in that package actually match your site rather than a calmer one.

2. What is the float made of, and how does it age? Ask for the resin specification and the UV stabilization approach, and ask what the supplier expects to happen to stiffness and color after a decade of exposure. A float that goes brittle is a diver job, not a warranty email.

3. Who designs the anchoring, and is it in the price? Mooring is the most site-specific part of a floating array — bank anchors, deadweight blocks and driven piles all behave differently depending on bank slope, bottom material and how far the water level moves. Most structure quotes do not include a mooring design. Confirm in writing whether yours does, who stamps it, and who carries the risk if the water drops four feet in August.

4. What is actually in the box? This is where quotes stop being comparable. A structure kit is floats, rails, module mounting hardware, inverter mounts and grounding. Panels, inverters, wiring, anchors and labor are separate line items (what's in a kit). If one quote is 30% cheaper, find out what it stopped including before you assume you found a deal.

5. What do you refuse to do? A supplier who says yes to everything is telling you something. Ask what water bodies they will not quote, what wave fetch they will not go past, and what they do when a site fails their own screen.

Questions about the numbers

Two real 2026 municipal builds in Ohio both landed near 87 sq ft of water surface per kW — Monroeville at 6 MW on 12 acres (APPA) and Lima at 2 MW on 4 acres (WOWO). Use 80–90 sq ft/kW for feasibility, not the tighter bare-array figure from a spec sheet, because the spec sheet does not include walkways, setbacks or the shape of your pond.

For structure cost, compare on dollars per watt of structure and nothing else. A 20 kW three-phase Gen3 kit carrying 32 × 640 W modules lists at $4,796, which is $0.234 per watt of structure; the 20 kW single-phase kit on 560 W modules lists at $5,680, or $0.282 per watt (Gen3 kit pricing). Those are structure-only numbers. Any supplier comparison that mixes structure-only against structure-plus-anchors is not a comparison (how suppliers differ).

Questions about tax-credit paperwork

This is the section that has changed most this year, and the one most likely to be handed to you late by a lender.

Qualified facilities that began construction after December 31, 2025 have to clear a material assistance cost ratio: 40% in 2026, 45% in 2027, 50% in 2028, rising to 60% in 2030 and later (McGuireWoods). A taxpayer can generally rely on a supplier's written certification about component sourcing and costs, provided they have no reason to know it is wrong — the certification safe harbor.

So the question to a supplier is not "are you compliant." It is: will you issue a written certification of component costs and sourcing for this order, in a form my tax counsel can rely on, and when? If the answer is vague, price the risk. More detail on how the test works is here.

One more moving part worth tracking: on June 6, 2026 a federal court vacated IRS Notice 2025-42 in full, which restored the 5% cost safe harbor as a beginning-of-construction method for larger solar projects, with an appeal expected (McGuireWoods). If your begin-construction position depends on which method applies, get current advice rather than a 2025 memo.

Questions about permits and water

Since Sackett v. EPA, many private, hydrologically isolated ponds may fall outside federal jurisdiction — but that is a site-specific and state-specific determination, and local building, electrical and interconnection permits apply regardless. Ask the supplier what they will actually do to help: confirm jurisdictional status, supply drawings a plan reviewer will accept, answer the utility's questions. Then ask what they will not do, so you can price that work into your own scope (jurisdiction and approvals).

Questions about delivery and the ten years after

Storm response in particular is worth testing before you need it — ask what the supplier tells an owner to do when a named storm is 72 hours out (storm protocol).

The bottom line

Floating solar quotes are not comparable until you have forced them into the same scope. Four documents do most of that work: the engineering package with its design basis, the bill of materials showing exactly what ships, the written certification for tax-credit paperwork, and a lead time with a freight term attached. If a supplier will produce all four without a fight, you are dealing with someone who has done this before. If they will produce none of them, you have learned that cheaply.

If you are an EPC or installer adding floating solar to your lineup, the dealer program is where that conversation starts, and unfamiliar terms are defined in the glossary.

This article is general information, not tax or legal advice. Tax credit eligibility, jurisdictional determinations and trade duties depend on facts specific to your project — consult qualified counsel before relying on any of it.

Sources: Olson Partners Law — §48E termination · Hunton — Section 232 minimum import prices · Solar Power World — ITC final determination · DNV — RP-0584 recommended practice · APPA — Monroeville, Ohio 6 MW · WOWO — Lima, Ohio 2 MW · McGuireWoods — FEOC material assistance guidance · McGuireWoods — Notice 2025-42 vacated