The signs are a roof covering with less remaining life than the 25-to-30-plus-year module life, a mount flashed on top of rather than under the upslope shingle course, an unconfirmed roof-structure load, and missing rapid shutdown, per the NRCA, NREL, and NEC 690.12.
Each sign traces to the roofing side of a solar array — the covering, the flashing, the structure, and the code that the array sits on rather than the panels themselves.
When Should a Roof Be Re-Roofed Before Solar?
A roof covering with less remaining service life than the array signals a re-roof before solar. Crystalline-silicon modules operate roughly 25 to 30-plus years and a covering replaced under a finished array forces a costly removal and reinstallation of the panels, per NREL and the DOE.
Module life sets the timeline a re-roof decision works against, because crystalline-silicon modules carry roughly 25-year performance warranties and degrade at a median near 0.5 percent per year to roughly 85 to 88 percent of rated output after 25 to 30 years, per NREL and the DOE. A covering with fewer years left than that span outlives its usefulness under the array, so replacing it first avoids the panel removal and reinstall a mid-array re-roof demands.
The re-roof-before-solar rule is a roofing rule of thumb rather than a code requirement, applied during the roof assessment that precedes any mount. A roof covering nearing the end of its service life, with curling, granule loss, or a deck soft underfoot, calls for the covering to be replaced or repaired first, so a roof replacement lands before the array rather than under it.
What Roofing Conditions Signal a Leak or Warranty Risk?
A mount flashed on top of the shingle course rather than tucked under the upslope course marks a leak path. The flashing flange sheds water onto intact shingles only when the flange sits under the upslope course, per the NRCA Rooftop PV Guidelines and IronRidge.
Mount flashing stays watertight when each attachment uses an integrated flashed foot whose upper flange tucks under the upslope shingle course, so water sheds onto intact shingles below, per the NRCA Rooftop PV Guidelines and IronRidge. A flashing sitting on top of the course leaves the fastener penetration exposed to runoff, the condition that produces a leak at the array foot years after the panels go on.
A flashing that does not match the roof-covering manufacturer instructions voids the roofing warranty, because the covering manufacturer specifies the flashing detail and a compatible sealant, per the NRCA and Solar Power World. Matching the mount flashing to those instructions keeps the roofing warranty intact, which is why the roofing scope of a solar panel roofing installation coordinates the attachment detail with the solar installer before the array is set.
What Structural and Code Signs Apply?
A roof structure of unconfirmed load capacity and a rooftop array missing rapid shutdown or firefighter access signal code and structural risk. Uplift and ballast follow ASCE 7, NEC 690.12 requires rapid shutdown, and IRC R324.6 sets firefighter pathways.
Roof-structure load is confirmed before install, because the array adds dead load and the uplift and required ballast follow ASCE 7, with corner and perimeter zones carrying more ballast than the field, per ASCE 7. A structure of unconfirmed capacity halts a ballasted or rail-mounted install until the assessment verifies the roof carries the added load, and the rooftop array itself carries an AHJ building and electrical permit while the underlying re-roof on a detached one- and two-family home counts as ordinary maintenance under N.J.A.C. 5:23-2.7.
Rapid shutdown and firefighter access govern the rooftop array under fire and electrical code, so an array without them fails inspection. NEC 690.12 drops conductors to 30 volts or less outside the array boundary and 80 volts or less inside within 30 seconds, the assembly fire rating applies to the module, mounting, and covering together under UL 790, and IRC R324.6 sets 36-inch firefighter pathways with an 18-inch ridge setback at 33 percent or less roof coverage and 36 inches above, per NEC 690.12, UL 790, and IRC R324.6.
A covering with less life than the 25-to-30-plus-year module span, a mount flashed on top of rather than under the upslope course, an unconfirmed roof-structure load, and a missing NEC 690.12 rapid shutdown or IRC R324.6 firefighter access each signal roofing work to settle before the array goes on.