Path-Q Solar
How much can panel degradation reduce lifetime solar production and expected bill savings?
Answer
Panel degradation gradually reduces output, so lifetime production and savings will be lower than if panels stayed at their initial output. The effect depends on the actual degradation rate, system age, climate, failure history, electricity use, and the value of self-consumed and exported energy.
Key points
- Model degradation annually rather than assuming the original production remains constant.
- Distinguish gradual power loss from sudden failures, soiling, shading, inverter problems, and warranty claims.
- The same production loss can have different financial effects depending on when energy is produced and how it is valued.
- A long-term model should include degradation sensitivity rather than one assumed rate.
What it depends on
- Panel technology and warranty assumptions
- Operating environment and maintenance
- System age and observed production history
- Electricity consumption and export value over time
Risks and trade-offs
- Using a low degradation assumption can overstate lifetime savings and asset value.
- Actual bill savings may change independently because rates, loads, and export arrangements change.
- Replacing degraded panels may involve compatibility, labor, disposal, and roof-access costs.
Information you may need
- Panel model, age, and warranty documentation
- Historical production adjusted for weather and outages
- Projected annual degradation cases
- Long-term load, rate, and export assumptions
Your next step
What to do next
Recalculate lifetime production and savings using at least low, expected, and high degradation cases and compare them with observed system performance.
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SQ00405