Solar Panel Performance Issues: What No One Tells You

Solar production projections are presented as reliable forecasts, but they're built on assumptions — and those assumptions are frequently optimistic. When reality falls short of the projection, the homeowner is left paying for energy they never received.

The Factors That Affect Solar Production

Solar production is affected by a complex set of variables that interact with each other. The most significant are:

• Shading: Even partial shading from trees, chimneys, or neighboring structures can significantly reduce production. Shading analysis is often done superficially during the sales process.
• Roof orientation and pitch: South-facing roofs at a 30-degree pitch are ideal. East- or west-facing installations produce significantly less, and this should be reflected in the projection.
• Equipment quality: Panel efficiency, inverter quality, and wiring all affect production. Budget systems with lower-quality components may underperform relative to projections based on premium equipment.
• Installation quality: Poor installation can reduce production and create reliability problems. Improperly wired panels, inadequate racking, and other installation errors are more common than the industry acknowledges.

How Production Estimates Get Inflated

Solar production software allows installers to adjust assumptions. By minimizing shading factors, using optimistic weather data, assuming premium panel performance, and using low degradation rates, an installer can generate a projection that looks significantly better than what the system will actually deliver.

There's no independent verification of these estimates at the time of sale. The homeowner is trusting that the numbers are honest. When they're not, the gap between projected and actual production falls entirely on the homeowner — in the form of higher utility bills and lower savings than promised.

Documenting and Addressing Underperformance

If your system is consistently producing less than projected, document it carefully. Pull your monitoring data for the past 12 months and compare it to the annual production estimate in your original proposal. A gap of 10% or more is significant and worth pursuing.

Notify your installer in writing and request an inspection. If they're unresponsive or the inspection reveals no correctable issues, the underperformance may be the result of an inflated projection — which is a form of misrepresentation that can support a contract challenge.