Shading loss

ID: concept:shading-loss
IRI: https://solarlattice.org/kb/concept/shading-loss
Status: active
Also known as: inter-row shading, near shading, row-to-row shading, Shade loss, mutual shading
Category: Design
Concept kind: physics

Shading loss is the energy lost when objects keep sunlight from reaching the modules, for example far horizons, trees, buildings, cabling, chimneys, or the next row of modules. Because cells and modules are wired in series, the power lost is much larger than the shaded area alone would suggest, and the actual result depends on string layout, MLPE, inverter MPPT behavior and shade-tolerant module types such as half-cut cells. Some inter-row shading always remains in large plants because shadows get very long early and late in the day, so row pitch and tilt are chosen as a trade-off against land use. The ground coverage ratio is part of that trade-off. On single-axis trackers, backtracking avoids east-west row shading, but uneven terrain can upset the backtracking geometry so that rows still shade each other. Monitoring platforms model shading as a reduction of plane-of-array irradiance, using either a shade table imported from PVsyst or a simple inter-row model built from pitch, tilt and module size. These irradiance-based models leave out the electrical effect of partial shading on modules and strings, so the energy loss they calculate is only approximate. In the field you can find shading by visual inspection, by comparing shaded and unshaded strings in monitoring data, or with shading simulations. Shade patterns change with the time of day and the season, and over the years as vegetation grows or new buildings go up. Shading on its own is not a safety problem. Prolonged shading can cause hot spots, though, which lead to burn marks, bypass diode failures or faster aging, so trimming vegetation and doing a shading analysis at the design stage are recommended.

Claims

`typical_power_loss`

c1 drafted · lead 1–5 PERCENT

Conditions: Typical cumulative annual shading loss of PV systems

Degradation and Failure Modes in New PV Technologies – Annex sec=h54 h=df63666c4734
Quantification of Technical Risks in PV Power Systems sec=h78 h=df63666c4734

review note: possible conflict with c2 (same source; check the conditions)

c2 disputed 20–30 PERCENT

Conditions: Energy losses observed up to this level on rooftop or facade systems

Degradation and Failure Modes in New PV Technologies – Annex sec=h54 h=df63666c4734
Quantification of Technical Risks in PV Power Systems sec=h78 h=df63666c4734

review note: possible conflict with c1 (same source; check the conditions)conflicts with: Shading loss (c3)

c3 verified · fact ≤ 1 PERCENT

Conditions: Annual shading loss below which row spacing is generally considered acceptable in utility-scale design

Utility Scale Power Plants - A Guide for Investors and Developers sec=7.2.3 h=e4ddc70cfb8d

verified by: review-workflowverified on: 2026-10-24review note: support check: partial - Passage says less than 1% annual loss may deem row spacing acceptable, but not specifically 'utility-scale' or 'generally' considered; roughly matches.; review: the compiler-flagged conflict (concept:shading-loss#c2) is a scenario difference, resolved at review