How to Use This Tool
Apply monthly shade exposure and system recovery to an unshaded forecast. Estimate annual solar energy and revenue lost to shading using affected share, shade severity and an editable mitigation factor.
The decision this tool supports
A shade percentage on one roof section is often incorrectly applied to the entire array without considering affected area or electronics mitigation. This page keeps the decision bounded to annual energy lost and the supporting outputs shown beside it. Solar Shading Loss does not import an account, infer a market rate, or silently substitute an industry average.
Inputs and units
The Solar Shading Loss calculation uses Unshaded annual generation, Array area affected, Average loss on affected area, System mitigation recovery, Energy value. Keep all money values in one currency and all time, distance, mass, energy or volume entries in the unit printed beside the field. Mixing Solar Shading Loss scopes can produce a plausible number with the wrong meaning.
- Unshaded annual generation is entered in kWh/year.
- Array area affected is entered in %.
- Average loss on affected area is entered in %.
- System mitigation recovery is entered in %.
- Energy value is entered in currency/kWh.
Formula and worked check
Whole-array loss rate = affected area × loss on affected area × (1 − mitigation recovery); lost energy multiplies unshaded generation. Twelve thousand kWh, 35% area affected, 40% local loss and 25% recovery imply 10.5% whole-array loss or 1,260 kWh. The Solar Shading Loss default is an executable known-answer case, not a benchmark or recommendation. Change one input and verify that the direction of annual energy lost still matches the stated relationship.
How to interpret the result
Use the result as a scenario range and compare it with interval production or professional shade analysis before investment decisions. The additional Solar Shading Loss outputs expose the denominator, comparison, capacity or reverse value needed to audit the primary result instead of presenting one unexplained number.
Assumptions
- Unshaded generation is a credible annual baseline.
- Affected area and local loss are energy-weighted averages.
- Mitigation recovery applies only to the modeled shade loss.
Save the Solar Shading Loss input values and date with any material decision. A later Solar Shading Loss rerun is reproducible only when the same assumptions and units are available.
Limitations and safety boundary
Real PV shading is nonlinear and depends on string layout, bypass diodes, season, irradiance and inverter behavior. Solar Shading Loss is an estimate and cannot replace a contract, local code, licensed professional, calibrated measurement, lender statement or platform report where one governs the decision.
Source and privacy
The Solar Shading Loss definition or rule was checked against NREL PVWatts Calculator documentation on 2026-08-26. Recheck NREL PVWatts Calculator documentation when a specification or policy behind Solar Shading Loss can change. Solar Shading Loss arithmetic runs in this browser tab; ecech does not receive the values through a calculation API.
Sources & assumptions
Tool Spec v2 · verified 2026-08-26. Platform rules and fees can change; the editable inputs remain authoritative for your account.
Official references
- NREL PVWatts Calculator documentation (checked 2026-08-26)
Model assumptions
- Unshaded generation is a credible annual baseline.
- Affected area and local loss are energy-weighted averages.
- Mitigation recovery applies only to the modeled shade loss.
- Real PV shading is nonlinear and depends on string layout, bypass diodes, season, irradiance and inverter behavior.
