Monsoon season runs from mid-June through the end of September, and the damage it does to solar arrays is rarely the rain. It is the wind arriving ahead of the rain, the debris that wind picks up, and the dust settling out of the sky afterward. A short list of jobs done in early June is worth more than anything you can do once a storm is overhead.
Clear everything loose before the first storm
Microburst gusts can exceed highway speed, and they hit from odd directions, including upward under the array. Anything loose on the roof becomes either a projectile or a dam.
- Nesting material under the panels. A packed nest catches wind, holds water against the roof, and blocks drainage. It is the most common thing we clear this time of year.
- Palm fronds, seed pods, and leaf litter. These collect along the low edge of the array and in roof valleys, exactly where water needs to move.
- Tumbleweed and yard debris that has blown up and lodged between rows.
- Overhanging branches. A limb above the array is the most preventable source of storm damage there is. Trim well back, since branches travel a long way in a gust.
- Roof drainage. Scuppers, valleys, and gutters clogged with debris turn heavy rain into standing water, and standing water finds the mounting penetrations.
Check the hardware holding the array down
Wind uplift works on the underside of panels, and that load travels into clamps, rails, mounts, and ultimately your roof structure. Those connections loosen over years of thermal cycling, because aluminum and steel expand and contract every single day here through a temperature swing most of the country never experiences.
Worth having looked at, ideally by whoever services the system:
- Clamp and rail fasteners still torqued rather than backed off
- Flashing and sealant intact at every roof penetration
- No lifted or visibly loose panel corners
- Wiring still clipped up beneath the array rather than sagging where wind can whip it
- Conduit straps and junction box covers secure
- Roof tiles around the array intact, since a cracked tile is where water gets in
Note your baseline production on a clear June day as well. If something changes in August, you want a number to compare against rather than an impression.
Close the array to birds before the storms arrive
Bird activity and monsoon season are really the same problem in the valley. Pigeons nest year-round here, so by June there is often material packed under the panels. That material catches wind, holds moisture against the roof deck during a storm, and blocks the drainage path at exactly the moment your roof is handling the most water it will see all year.
Clearing it out and fitting perimeter mesh before the season starts solves both at once. Doing it in the other order, after a storm has soaked a nest and driven the mess across your roof, is a far bigger cleanup and a far bigger bill.
What to check after a big storm
Wait until the roof is dry, and stay on the ground for the first look. Binoculars are enough.
- Panels that have shifted, lifted at a corner, or fallen out of alignment with the row
- Cracked or spidered glass, which often appears as a fine web radiating from an impact point
- Dented frames, or debris resting on top of the array
- Wiring hanging below the panels
- Displaced or cracked roof tiles, particularly around the mounts
- A dead string or a step down in monitoring data over the following clear days
Photograph anything that looks wrong before anyone touches it. Insurance claims and warranty conversations both go better with dated images taken the day after.
One more thing about the rain itself: it does not clean your panels. Storm rain here falls through air carrying suspended dust and leaves a muddy film that dries into streaks along the lower edge of each panel. Arrays usually come out of monsoon season dirtier than they went in, which is why the most valuable wash of the year is the one booked for October rather than May.
We handle pre-season clearing, bird proofing, and post-season washes with deionized water, and both of those windows fill up fast. Get on the schedule ahead of the first haboob rather than after it.