Some drop in solar production through fall and winter is normal in Arizona, because days are shorter and the sun sits lower in the sky. The real question is whether your system is lower than it was at the same time last year. That comparison, not the summer peak, tells you whether something is wrong.
AZ Solar Maintenance helps East Valley homeowners sort normal seasonal change from real problems through solar monitoring, solar panel inspection, and solar panel cleaning.
Why output naturally dips this time of year
A few things change as the year turns toward winter:
- Fewer daylight hours. Less time in the sun means fewer hours of production each day.
- Lower sun angle. Sunlight hits the panels at a shallower angle for much of the day.
- Longer shadows. A low sun can cast shade from trees, chimneys, or nearby structures that never touched the array in summer.
Cooler temperatures help a little, since panels tend to work more efficiently when they are not baking, but that usually does not make up for shorter days. None of this means anything is broken.
The wrong comparison: summer vs now
Looking at your app in October and comparing it to June will almost always look alarming. That is not a useful test.
The useful comparison is your system against its own history for the same stretch of the year. Monitoring from AZ Solar Maintenance works that way: production is watched against what your system's own history shows it should be producing, not a generic assumption.
Signs it is more than the season
- Output well below the same month last year with similar weather
- One string or section producing much less than the rest
- Days of zero output on clear days
- Repeating error codes on the inverter
- A sudden step down rather than a gradual change
Any of those point past normal seasonal change.
Soiling still matters in the cool months
Most East Valley systems collect the heaviest film after monsoon season ends in the fall. Dust and haboob fallout from summer can still be sitting on the glass, and a light rain often leaves streaks and spotting instead of washing it off.
Lower sun plus a dirty array is a double hit. Fall is a common time to schedule a clean, and every visit includes a production check before and after, with photos.
What you can check from home
- Pull up the same month from last year in your monitoring app.
- Compare a few clear days now to clear days then.
- Check for error codes on the inverter or in the app.
- Look at the panels from the ground for film or droppings.
- Note any new shade, like a tree that has grown or a new structure nearby.
If you do not have last year's data or cannot get into the app, that alone is a reason to get the system watched.
When to book an inspection
If production is clearly below last year on clean glass, an inspection is the next step. It covers panels, racking, flashings, wiring, connectors, and the inverter, and compares current output to what the system should be producing. You get a photo report either way.
FAQ
How much lower is normal in winter? It varies with each system's tilt, direction, and shade. Your own history is the best guide, which is why monitoring compares the system to itself.
Do I need new hardware for monitoring? Usually no. Most systems already report to the inverter manufacturer's platform.
Is fall a good time to clean? Yes. The heaviest film often builds by the end of monsoon season, and a clean now means the shorter days are not working through dirty glass.
Next step
Send your address and a screenshot of recent production through the contact page. AZ Solar Maintenance will quote monitoring, cleaning, or inspection flat and the same day.