SolarSoiled · Program
One cleaning can remove both seasonal buildup and residue that survives rain. Together, those benefits may justify a service visit even when either benefit alone would not. SolarSoiled maps rooftop arrays, estimates system size, and identifies conditions that merit closer inspection. Its tools help homeowners and service providers explore cleaning economics, with Persistent Soiling savings shown as conditional scenarios until supported by site-specific evidence.
The cleaning decision
Regular Soiling is seasonal: an early-July cleaning protects the final dry-season months. Persistent Soiling can survive rain, so a confirmed loss can add recovery across a full year. The tools show both components, one cleaning cost, and the resulting net benefit in the same scenario.
Persistent residue stays conditional until a site inspection confirms it and production history or a calibrated assessment estimates its energy effect. That preserves the distinction between a risk screen and a measured loss.
Illustrative combined scenario
$120 seasonal recovery + $220 conditional persistent recovery = $340 combined recovery. A $300 cleaning visit leaves $40 in net benefit after the visit cost.
These are example values only. The calculator applies the same structure to a property's estimated system size, local rate, selected cleaning method, and supported Persistent Soiling loss.
SolarSoiled pilot
We are seeking cleaning and maintenance partners to test whether SolarSoiled can improve property targeting and identify worthwhile cleaning opportunities.
A pilot can combine ranked properties, clear customer reports, and your local service prices. Your team manages customer contact and cleaning; together, we collect inspection findings and, where available, customer-authorized production data to evaluate results and improve the model.
Discuss a solar pilotLive today
detected rooftop-solar systems mapped across Santa Cruz County, California. Free to explore, no account, no signup.
3,362 separate arrays, because a single system is often several panel groups on one roof.
The published dataset carries roof geometry, soiling scores, and household system totals and nothing else: anonymous IDs in place of addresses, owner names, and parcel numbers. Automated checks keep private property details out of the published map.
We publish anonymous group IDs so people can use the tool while homeowners remain unlisted.
How it works
Nobody visits the house and nobody logs into a utility account. Everything below runs on photographs and weather records that are already public.
Santa Cruz County publishes aerial imagery from its own survey. Each pixel covers 21 cm of ground, so a solar panel is about eight pixels across: enough to trace detected array shapes while preserving residents' anonymity.
A model trained on hand-labelled rooftops draws an outline around each panel group it detects and reports how much roof it covers in square metres. That outline is the only thing measured directly from a roof.
Modern panels produce about 220 watts per square metre of glass, and roughly 84% of an outlined array is glass; frames and gaps make up the remainder. That works out to 5.41 square metres per kilowatt, a ratio we checked against 130 local building permits where the installed size is on record.
Local weather and air-quality records estimate Regular Soiling: dust that builds through the dry season and resets with winter rain. A second Persistent Soiling screen uses each panel group's racking angle and nearby canopy to prioritize arrays for a visual check. A visual check confirms residue; production history or a calibrated assessment estimates its energy effect. The two layers use different time horizons and remain distinct until that evidence exists.
Finding the arrays
It finds 80% of the arrays that are really there, and almost everything it points at is really an array.
Scored as F1 — the standard measure that counts misses and false alarms together. Range 0.798 to 0.853 across repeated samples, against a pass mark of 0.75 set before the run.
Out of every ten arrays on a roof in the test set, it finds eight and gets the outline right. We set the pass mark before running it, scored independent photographs from a held-out town, and locked the settings on a separate batch first.
What scale looks like
Nothing in the software is specific to Santa Cruz. It is simply where we started: the county flies its own aerial survey at 21 cm, and at least thirteen other US counties publish surveys about that sharp. Expanding to each county means licensing the imagery, retraining the detector, and completing local validation before we publish a roof-level result. That is the work support pays for.
Covering the whole country is a different constraint, and there it really is the photographs. The imagery that reaches everywhere is coarser than a county survey, and below a certain pixel size a panel stops being a shape and becomes a smudge. The two national figures below are how many US rooftop panels each level of imagery would put in reach; local validation will establish accuracy.
Today
Santa Cruz County, 21 cm
1,865 households
Live, free, and public, at a measured 0.826 F1, with tools anyone can open in a browser.
Next
60 cm imagery, nationwide
~50% of US rooftop panels
Aerial photography at this resolution covers the whole country, and the pipeline already runs on it. Carrying today's accuracy across requires retraining and validation.
With support
30 cm imagery or better
75%+ of US rooftop panels
Sharper photographs would let us read more of the panels themselves, including module layout and clearer edge-band evidence. The Santa Cruz pilot already measures roof geometry and nearby canopy from public laser scans.
What we found
Regular Soiling is ordinary dust and pollen that accumulates from April through September, then resets with winter rain. We model an early-July clean and value the final three dry-season months of output it protects. Under the coastal pilot's assumptions, seasonal recovery alone did not exceed the assumed cleaning cost for the detected systems we mapped. That bounded result changes when seasonal buildup is heavier, a system is larger, or a local service price differs.
Persistent Soiling changes the economics. A pollen film, cemented edge band, or biological growth can survive winter rain and reduce production across the next 12 months. One cleaning can recover both the seasonal buildup and a confirmed persistent layer, so the calculator compares their combined recovery with one service cost. The Persistent Soiling screen identifies physical settings worth inspecting; it does not assign a loss percentage on its own.
What the model measures
The model reports a county-wide soiling estimate from local weather records. Of the 1,865 households we mapped, more than nine in ten land between 2.5% and 2.9% of output lost.
Your system size comes directly from the photograph of your roof. That measurement decides whether the estimated loss is $9 a year or $460.
The Persistent Soiling screen adds per-array racking angle and nearby canopy. It ranks the physical settings most worth an inspection; a field check confirms residue, while production history or a calibrated assessment estimates its energy effect.
Persistent Soiling screening
The Regular Soiling estimate is a neighborhood baseline from weather and air-quality records. The Persistent Soiling screen currently weights two per-array measurements: racking angle at 70% and nearby canopy at 30%, using canopy amount and nearest-canopy distance. Panel layout and orientation remain visible as field-inspection context; the current score uses the two measured inputs above. The screen highlights the top tenth of scored panel groups, then keeps its dollars conditional until a visual inspection confirms residue and production history or a calibrated assessment estimates its loss. Each inspection adds the ground truth needed to calibrate the next version.
The screen tells us where to look first. A roof becomes a cleaning recommendation only after a visual check or production record confirms Persistent Soiling.
Current screening policy
Inspection priorityPublic roof data
Racking angle
Lidar-fitted roof plane
70% of scoreNearby canopy
Canopy amount + distance
30% of scorePersistent Soiling
Inspection priority
Rank the top 10% of panel groups, then send those candidates to a visual inspection.
Confirm residue, then estimate its effect
A field check confirms residue; production history or a calibrated assessment estimates persistent loss and cleaning value.
Next calibration targets
These candidate inputs will earn a model weight after they improve prediction against field inspections or measured production recovery.
Public lidar + sun-path geometry
Estimate when tree or roof shade reaches an array, whether its plane faces the cooler side of the roof, and how slowly the surface is likely to dry after rain.
Repeated shade and long damp periods create better conditions for moss, lichen, and persistent biofilm.
Roof plane + aerial imagery
Map the low edge of each panel group relative to roof valleys, gutters, and tree debris paths, then look for settings where water and particles repeatedly collect.
Slow drainage and trapped debris can concentrate mineral residue or create a persistent lower-edge band.
High-resolution public aerial imagery
Screen for stable lower-edge darkening, streaks, or non-uniform panel color that could merit a closer look across repeated image dates.
A visible band can be a direct clue for accumulated residue or organic material, but lighting, reflection, and shadow can mimic it.
Land cover, facility maps, roads + seasonal wind
Combine nearby vegetation, bare soil, agriculture, roads, and permitted facilities with prevailing wind direction into one exposure measure.
Pollen, dust, and sticky fine particles can arrive from different sources, then become more persistent when a surface dries slowly.
The decisions behind it
Why we give it away
Getting more power out of panels a household already paid for is one of the fastest ways to improve solar value. Regular Soiling gives us a neighborhood baseline, and Persistent Soiling gives us a way to focus on the arrays most likely to benefit from a closer inspection and cleaning.
The public map and calculator are free. Partners can support expanded coverage, tailored reports, and validation while homeowners, installers, and researchers keep access to the underlying method. Every verified inspection or production comparison can turn today's transparent heuristic into a stronger calibrated tool.
It is the same job as our airline sustainability ranking: turn public information into something someone can act on.
