How we calculate

What PanelAudit does

PanelAudit estimates how much energy a residential solar system may be losing due to age, climate, soiling, and equipment factors. It identifies likely causes and recommends whether professional inspection is warranted.

It is not a replacement for professional inspection. It is a screening tool to help solar owners understand whether further investigation is worth pursuing.

Why ranges, not exact numbers

Solar performance depends on dozens of variables we cannot measure remotely: panel tilt, orientation, local micro-shading, wiring quality, inverter firmware, and more. Providing a single precise number would be misleading.

Instead, we provide conservative ranges that represent the likely band of performance loss given the inputs you provide. The wider the range, the higher the uncertainty.

Our model

The diagnosis engine layers four factors:

  1. Age-based degradation — All solar panels degrade over time. Published research (Jordan & Kurtz, NREL) establishes median degradation rates of ~0.5–0.8% per year for crystalline silicon panels. We model cumulative degradation as a function of system age.
  2. Climate adjustment — Panels in hot-arid climates experience accelerated thermal stress. We adjust loss estimates by climate zone using NREL and IEA-PVPS regional performance data.
  3. Soiling risk — Dust, pollen, and debris accumulation varies by region. Arid and agricultural states have higher soiling losses. We use published soiling loss data from SunSpec Alliance research.
  4. Equipment factors— If inverter brand is provided, we factor in the inverter's typical lifespan and age-related efficiency curves.

Fault identification

Each fault type (hotspots, soiling, inverter issues, wiring, shading) is scored independently based on how strongly the input profile correlates with known risk factors. Faults are ranked as "likely" or "possible" — never presented as certain.

Data sources

  • NREL — National Renewable Energy Laboratory degradation studies
  • IEA-PVPS — International Energy Agency PV performance data
  • SunSpec Alliance — Soiling and monitoring standards
  • PVsyst — Industry-standard PV simulation reference data
  • Jordan & Kurtz (2013) — "Photovoltaic Degradation Rates" meta-study

What we don't do

  • We do not store or sell your data
  • We do not guarantee specific outcomes
  • We do not replace qualified electrical inspection
  • We do not fabricate technical precision

Conservative by design

When in doubt, our model errs toward conservative estimates. We would rather understate a problem than overstate it. If uncertainty is high, the output says so explicitly.

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