- Cleaning cadence1–2 times a year here
- Summer soiling loss~3–7% on an unwashed array
- Most likely to failThe inverter, at 10–15 yrs
- Best free habitCompare output year on year
The short version
A solar array has no moving parts and needs very little. What it does need in the Sacramento Valley is occasional cleaning — because of dust, pollen and wildfire ash — and somebody paying attention to the monitoring data. Almost everything else sold as solar maintenance is optional at best.
Cleaning: when it genuinely matters here
Soiling losses vary enormously by climate. In a wet climate rainfall does most of the work. The Sacramento Valley has an unusual pattern that makes cleaning more relevant than the national average suggests:
- A long dry season. From roughly May to October there is often no meaningful rain at all, so nothing washes the array for months — and those are precisely the highest-production months.
- Agricultural and road dust. A genuine factor across the valley floor, and more so on rural properties in Wilton, Galt, Dixon and Winters.
- Wildfire ash. Late-summer smoke events deposit fine ash that is significantly more adhesive than dust, and they coincide with peak production.
- Spring pollen. Heavy in the oak-canopied suburbs, and sticky.
Realistically, expect soiling losses somewhere in the region of 3–7% over a dry Sacramento summer on an unwashed array, and more after a significant smoke event or under trees. Once or twice a year is a sensible cleaning cadence here — typically late spring after pollen, and again in early autumn after fire season.
How to clean panels safely
- Early morning or evening. Cold water on hot glass risks thermal shock, and a hot roof is dangerous to work on.
- Plain water and a soft brush or squeegee on a pole. Deionised water if you have hard water and want to avoid spotting.
- No pressure washers — they can force water past the module seals.
- No abrasive pads and no detergents that leave a residue film.
- From the ground wherever possible. A roof is not worth a fall, and professional cleaning costs far less than an injury.
Monitoring: the maintenance that actually finds problems
The single most valuable maintenance habit costs nothing: look at your production data occasionally and compare it with the same month last year. Not against the month before — seasonal variation will mislead you — but year on year.
If you have module-level electronics you can see each panel individually, which turns diagnosis from a site visit into a thirty-second check. A single panel reading differently from its neighbours is a failed optimiser or microinverter, and you will usually spot it long before it shows on a bill.
Also worth knowing: monitoring dropping offline is usually not a system fault. A new router, a changed Wi-Fi password or a 2.4 GHz network being retired will take monitoring down while the array carries on generating perfectly well.
What to expect over twenty-five years
| Component | Expected life | What to expect |
|---|---|---|
| Panels | 25–30+ years | Gradual degradation around 0.3–0.5% a year. Individual failures are rare. |
| String inverter | 10–15 years | The component most likely to need replacement. Plan for it. |
| Microinverters / optimisers | Typically warranted 25 years | Occasional individual failures; replacement means roof access. |
| Racking & flashing | Life of the array | Worth a visual check every few years, particularly after high wind. |
| Monitoring hardware | Variable | Most likely thing to need attention, and the least consequential. |
Critter guard, and whether you need it
Pigeons and squirrels nest in the gap between panels and roof, and they chew wiring. It is a genuine and common problem in the older tree-heavy suburbs — Carmichael, Fair Oaks, Arden-Arcade, East Sacramento. Mesh critter guard around the array perimeter is inexpensive when fitted at installation and more awkward to retrofit, so it is worth deciding at design time rather than after the first nest.
What is usually not worth paying for
- Recurring maintenance contracts on a healthy residential system with no moving parts. Cleaning and an occasional inspection are cheaper bought as needed.
- Panel coatings claiming to reduce soiling. The evidence for a durable benefit is thin, and some coatings degrade in a way that makes things worse.
- Frequent professional cleaning beyond once or twice a year. Past that the marginal recovered production rarely covers the cost.
If something looks wrong
We service and repair systems of any brand, including those whose original installer has gone out of business. Describe the symptoms on the phone first — some faults, particularly monitoring dropouts, can be narrowed down without anyone going on a roof.
Written by the Sacramento Solar team for Sacramento-area homeowners. We install solar; we are not tax advisers, accountants or financial advisers. Figures are ranges current as of early 2026 and are offered as orientation, not as advice about your own situation. Verify current programme rules with your utility, the relevant agency or a qualified professional.