Percent complete vs. percent installed: verifying an EPC draw request

An EPC's draw request shows 72% complete. The schedule of values backs it up: engineering done, procurement paid, mobilization logged, foundations in, racking most of the way up. The number is defensible on paper. It's also not the same question as "how many modules are actually bolted to racking and wired into a string today," which is the number that should matter when you're releasing the next tranche against an interconnection milestone.

That gap between percent complete and percent installed is where most draw disputes start, and it's rarely fraud. It's two different accounting systems pointed at two different things.

Percent complete vs. percent installed

Percent complete, as most EPCs report it, is a cost-weighted figure tied to the schedule of values. It credits engineering, procurement, site prep, racking installation, and commissioning as separate line items, each worth a slice of the contract. An EPC can legitimately be 70% complete on cost while sitting at 40% on physical modules racked, because procurement and mobilization front-load a lot of dollars before a single panel goes up.

Percent installed is narrower and dumber, in the good sense: modules on racking, divided by modules in the interconnection agreement. No weighting, no judgment calls about what counts as "substantially complete." It's a count.

Most construction loan agreements and PPAs tie drawdowns and milestone payments to the second number, or to a hybrid that references nameplate capacity installed. But the number that shows up in the draw package is usually the first one, because that's what the EPC's project controls software spits out by default. If your draw procedures don't specify which one governs, you're implicitly trusting the EPC's self-reported progress to stand in for a count nobody has independently made.

How to check it before you sign the draw

A few things to pull before a draw gets approved, in order of how fast they tell you something:

Get the module count behind the percentage. Ask the EPC's project manager for the actual number, not just the percent: how many modules racked and wired, out of the total in the interconnection agreement, as of the draw cutoff date. If the EPC can't produce that number quickly, that's itself informative. A crew at 70% installed can usually tell you the count in an afternoon.

Cross-check against the table layout. Most sites are built in tables of a known module count. If the site plan calls for 480 tables at 28 modules each and the EPC claims 70% installed, that's roughly 336 tables substantially complete. Walk the staging and laydown photos, or the weekly progress photos most EPCs already supply, and see if that many finished tables is remotely plausible given what's visible.

Reconcile against the inverter and combiner box count, not just modules. A site can have a lot of modules racked and still be far from a milestone if the inverters and combiner boxes aren't energized yet. Draw schedules on some deals weight these separately; check which milestone the draw is tied to.

Walk it or fly it. For a site under a few megawatts, a site visit by the owner's engineer settles the question in a day. For anything larger, or for a portfolio where you're verifying ten or twenty sites a quarter and can't put a boot on every site, that's the point where a physical site visit stops scaling and you need another way to get an independent count: an aerial or satellite pass that counts installed modules, tables, and inverters directly from imagery, so the number you're reconciling against isn't the EPC's own progress report.

That's the gap Solar Panel Counting is built for: a counted inventory of modules, tables, and inverters at a site, pulled from very high-resolution imagery each quarter, so a lender, IPP, or asset owner has an as-built number to check against the draw schedule instead of taking the EPC's percent-complete figure on faith.

None of this is about assuming bad faith from the EPC. Percent complete and percent installed are legitimately different measurements, and a contractor reporting the first one accurately isn't lying about the second. The fix is procedural: decide up front which number governs your draw, and have a way to check it that doesn't depend on the same party who's asking to get paid.

If your draw schedule is written against percent installed rather than percent complete, an independent counted inventory each quarter is worth building into the process now, before the next draw request lands on your desk.