Measuring production loss from your monitoring app.
Short answer: Solar production fluctuates daily based on cloud cover, dust, panel temperature, and time of year. The signal that says 'my panels need cleaning' is finding a sustained 7%+ decline over 14+ days, normalized for weather. Every monitoring app has a way to view this — but the specific dashboards vary. The signals to watch: daily kWh vs expected, peak-hour kW output, and any sudden drop on a single panel (visible only in Enphase per-microinverter view).
The three numbers that matter
- Daily kWh generation — total energy your panels produced each day. The headline number on most apps.
- Peak-hour kW output — the maximum instantaneous power. Usually mid-day on a clear day.
- Cell-level or panel-level production — visible only on Enphase (per microinverter) or SolarEdge (per optimizer). Not visible on SMA central-inverter systems.
What "normal" looks like
Sunny day baseline for a typical Yolo system:
- Mid-summer (June–July): 6–8 kWh / kW-installed / day (clean panels)
- Mid-winter (December–January): 2–3 kWh / kW-installed / day
- Spring / fall (April / October): 4–5 kWh / kW-installed / day
So a clean 8 kW system in July produces ~48–64 kWh/day. The same system in December produces ~16–24 kWh/day. Comparing across seasons doesn't tell you anything about cleanliness; comparing same-season-this-year to same-season-prior-year does.
The 7% threshold
If your panels are producing 7% less than expected for the season (compared to the same dates a year ago, or compared to the system's modeled output), they need cleaning. Reasons:
- 3–5% loss = soft-cleanable dust film
- 5–10% loss = soft-cleanable + slight thermal loss from dust insulation
- 10–18% loss = baked-on film, multi-pass clean needed
- 18%+ loss = wildfire ash, or other emergency
Per-app guidance
Enphase Enlighten
- Open the app → Energy → switch to "Year" view → look for trend lines
- Per-panel: tap "Modules" → grid shows each microinverter's daily output
- Most-useful detail: a single panel showing 20%+ less than its neighbors usually means a panel-specific issue (bird droppings, debris, microcrack)
SolarEdge mySolarEdge
- Dashboard → Production → "Past 30 days" comparison to prior-year same period
- Per-panel via "Layout" view if you have power optimizers
- Most-useful detail: the production-vs-expected chart (your system's design model) shows when reality is diverging
SMA Sunny Portal
- Central-inverter systems — no per-panel detail
- Watch total daily kWh vs prior-year same date
- Watch peak kW during noon hour
- Most-useful detail: any sustained 7%+ delta over 2 weeks is the signal
Bring screenshots to the home visit. When network specialists arrive, the most useful single document you can hand them is your monitoring app's last 90 days. They'll see the pattern instantly. Cleaning starts there.