Array Removal and Reinstall for a Reroof SOP

Purpose

A detach and reset puts a working array on the ground and asks a crew to rebuild it, with a roofer's schedule driving the calendar and a homeowner watching. This procedure guarantees that the array going back up is electrically and mechanically the same array that came down, and that the shop can prove it.

Two failures pay for this document. The array that comes back producing less than it did, with nobody able to say whether it was the removal, the roofer, or a module that was already weak, because no pre-removal readings exist. And the penetration that lands in sheathing instead of a rafter, holds for two years, then lets a mount pull through under snow load. Both are invisible on handover day, and both trace to a record nobody wrote.

Scope

Covers full or partial array removal and reinstall on residential and small commercial pitched roofs where the covering is being replaced, from the scope agreement through re-commissioning and customer sign-off.

Does not cover the roofing work itself, which belongs to the roofing contractor and their warranty. Does not cover a reroof where the array is relocated, resized or moved to new racking, which is a new design and goes back through permitting. Does not cover module replacement for damage found during the work; that hands off to the module damage and warranty claim SOP.

Roles and responsibilities

Procedure

Step 1 - Agree the scope with the roofer in writing before a single module moves. Fix the calendar window, who supplies and installs the flashings, whether the deck is being replaced, and who carries the roof warranty over the mount penetrations. Acceptance: a signed scope naming the flashing type and the penetration owner. Wrong looks like a verbal agreement the morning of; stop, because when a leak appears at a mount two winters later the shop and the roofer point at each other and the customer sues both. Hazard is commercial, and the legal effect of who signed what is a question for your own attorney.

Step 2 - Shut down and isolate in sequence before touching any conductor. Open the AC disconnect first, then the DC disconnect, then lock and tag. Prove dead using the live-dead-live sequence at NFPA 70E-2021, 120.5, under the electrical work practices at 29 CFR 1910.333(b)(2) rather than 29 CFR 1910.147, which excludes electrical utilization work at its own (a)(1)(ii)(C). Acceptance: zero volts at the inverter DC input terminals with the proving instrument verified live before and after. Wrong looks like a zero on a meter nobody proved; re-do on a known live source. Hazard, and it is the one this trade loses people to: modules generate whenever lit, so conductors between the array and the open DC disconnect stay live in daylight and nothing upstream of that disconnect is dead until it is de-mated.

Step 3 - Record the as-is electrical and physical state, on the roof, before anything comes off. Record the serial at every grid position; measure open-circuit voltage and short-circuit current per string with the back-of-module temperature taken at the same moment; mark and photograph every mount penetration relative to two fixed references such as a ridge and a rake edge. Acceptance: a serial at every position, Voc and Isc per string with its temperature, and a penetration count matching the mounts about to come off. Wrong looks like readings taken without a temperature, which cannot be compared to anything later; re-do, because the re-commissioning gate in Step 9 rests on that pair. Hazard: roof work under the job's fall protection plan, per 29 CFR 1926 Subpart M at 6 feet for construction-classified work, and a roof surface in full sun runs hot enough to burn a bare forearm laid against it.

Step 4 - De-mate connectors only after confirming near-zero current, then remove modules two-handed. Clamp-meter each home run and confirm current at or near zero before separating any PV connector, because these are generally not load-break rated and an arc destroys the contact silently. Cap the open ends. Acceptance: every connector separated with its clamp reading logged, every module labeled with its grid position as it comes off. Wrong looks like a connector pulled under current, leaving a discolored contact you meet again as an arc fault; replace that pair rather than re-mating it. Hazard: a 400 W class module is a two-person lift in still air and a sail in any wind, so stop handling modules when wind moves one in your hands.

Step 5 - Stack modules on edge, face to face, off the roof and out of the traffic path. Use an A-frame rack or the original packaging orientation, foam or cardboard between faces, covered and secured against wind. Acceptance: nothing flat-stacked above the manufacturer's stated height, nothing leaned unsupported against a wall, nothing stored face-up in a work area. Wrong looks like a stack where a ladder can fall against it; move it. Hazard: the backsheet is the vulnerable surface, and a scratch through it is both a warranty exclusion and a future ground-fault path, so nothing is dragged across a face or a back.

Step 6 - Remove rails and mounts, then hand the roofer a marked deck. Take mounts off in an order that keeps rails supported, and mark each penetration with a durable marker plus a dimensioned sketch, because the new underlayment covers every surface mark you leave. Acceptance: penetration count on the sketch equals penetrations removed, each dimensioned from two fixed references. Wrong looks like relying on old holes staying visible; they will not be. Hazard: an open penetration is a water path, so every hole is sealed to the roofer's detail the same day it is opened.

Step 7 - Set new mounts into structural framing, with every pilot hole verified. Locate rafters with a scan, confirm each with a pilot hole, and inspect the shavings: rafter wood comes out as long fibrous shavings, sheathing alone comes out as thin surface dust. Flash every penetration to the roofer's detail. Acceptance: shavings confirm framing at 100 percent of mounts set, with every dust-only pilot sealed, logged and relocated, and lag embedment meets the racking manual for that fastener and framing species. Wrong looks like dust-only shavings. Stop rule: do not set a mount on a miss; seal the miss hole to the roof detail, log it, relocate within the manual's allowable span, and re-verify. Hazard: a mount set into sheathing holds through the punch list and fails under the first heavy snow load, taking the array with it.

Step 8 - Rehang modules to the recorded map, re-mate, torque and mark. Return each module to the grid position its label carries, torque module clamps and lag fasteners to the values in their own manuals (they differ, and the module maker also publishes a permitted clamp zone), and paint-mark every fastener after torque. Acceptance: 100 percent paint-marked, plus a calibrated-wrench spot re-check on at least 10 percent of clamps, all holding. Wrong looks like a clamp outside the published clamp zone, which voids the module warranty and starts a stress crack; re-position it. Hazard: re-mate connectors with the DC disconnect still open and locked, never on a closed string, and a connector pair from two different manufacturers is not an approved mating even where it clicks.

Step 9 - Re-commission against the as-is record, temperature corrected, before anyone talks to the customer. Re-measure Voc and Isc per string with back-of-module temperature, correct both readings to the same reference with the datasheet coefficient for that model, and confirm every module reports on the platform. Acceptance: corrected Voc within 2 percent of the corrected pre-removal figure, module reporting count complete, and no new ground-fault or arc-fault code after a full day. Wrong looks like a corrected Voc low by more than 2 percent, pointing at a missing module, a bypass diode gone conductive, or a connector not fully seated; stop and find it rather than handing over a system quietly one module short. Hazard: this step energizes, so close DC then AC, the reverse of shutdown, and stand clear of the inverter enclosure on its first grid connection.

The record this produces

One detach and reset record on the job: the signed roofer scope naming the penetration owner; the pre-removal serial-to-position map; pre-removal Voc and Isc per string with back-of-module temperature and the coefficient used; the dimensioned penetration sketch with counts; connector clamp readings at de-mate; every pilot verification with pass or miss and the disposition of each miss; torque values by manual with spot re-check results; post-reinstall Voc and Isc with temperature; the corrected comparison and its percentage; and the customer sign-off.

Read later by the warranty desk, when a module fails and the manufacturer asks whether it was ever removed; by the roofer or the shop's insurer, when a leak appears at a mount and the question is whose penetration and whose flashing; and by the next service tech, who needs the pilot-miss log to know which mounts sit off pattern.

Worked pass

A 28-module array, 400 W modules, 11.2 kW DC, two strings of 14, 46 mount penetrations, roof covering replaced with the deck retained.

Step 3 records 28 serials by position and measures string 1 at 488 V open circuit with a back-of-module temperature of 45 C. The datasheet coefficient for this model is -0.29 percent per degree C of Voc; mainstream mono modules commonly publish between -0.24 and -0.30, so the datasheet governs rather than the band. Corrected to 25 C: 488 divided by 0.942, or 518 V. The same figure is checked against the site's extreme minimum ambient of -5 C, where corrected Voc reaches 518 multiplied by 1.087, or 563 V, under the 600 V ceiling NEC 690.7 sets for PV dc circuits on one- and two-family dwellings in the adopted edition. The string is unchanged, so this confirms rather than recalculates.

Steps 4 through 6 run clean, all 46 penetrations sketched from the ridge and the west rake.

Step 7 fails. Of 46 pilot holes on the new deck, 43 return long fibrous shavings and 3 return surface dust only, all three in the same rail run, because a course had shifted and the crew was working off surface marks rather than the dimensioned sketch. Stop rule taken: no mount set on any of the three. Each miss hole is sealed to the roofer's detail with the roofer present and logged with its dimension, and the three mounts are relocated within the racking manual's allowable span, re-piloted and re-verified. Final tally: 46 mounts set, 49 pilot holes, 3 sealed misses on the record.

Step 8 rehangs all 28 modules to position. Clamp count is derived rather than guessed: 13 gaps between modules in each row multiplied by 2 rails is 26 mid clamps, plus 4 end clamps, so 30 per row and 60 across two rows. All 60 are paint-marked after torque and 6 of them, which is 10 percent, are spot re-checked with a calibrated wrench and hold.

Step 9 measures string 1 at 525 V with a back-of-module temperature of 20 C. Corrected: 525 divided by 1.0145, or 517.5 V, against the pre-removal corrected figure of 518.0 V. The delta is 0.5 V, or 0.1 percent, inside the 2 percent gate. Back-of-module temperature reads a couple of degrees below cell temperature, which at this coefficient is worth under 0.6 percent and so sits inside the gate rather than beside it. All 28 modules report on the platform and the inverter log is clear of ground-fault and arc-fault codes after a full production day. The customer signs off with the three sealed pilot misses named on the record.

References

• 29 CFR 1926 Subpart M and 29 CFR 1910.28 for fall protection, applied by activity classification.
• NFPA 70E-2021, 120.5, for live-dead-live verification; 29 CFR 1910.333(b)(2) for electrical work practices, with 29 CFR 1926.417 as the construction counterpart.
• NEC Article 690, including 690.7 for maximum PV dc circuit voltage, in the edition your AHJ has adopted.
• The racking manufacturer's manual for fastener embedment, allowable span and torque; the module manufacturer's manual for clamp zone and stacking limits.
• See related: the module damage and warranty claim SOP, and the monitoring setup and customer handover SOP for restoring module mapping after a rehang.