Understanding Solar Panel Degradation
All solar panels experience a gradual, predictable decline in electricity output over their operational life — a phenomenon referred to as degradation. This is a normal characteristic of photovoltaic technology and is carefully quantified by manufacturers, accounted for in system design projections, and protected against through warranty provisions.
Degradation Rates by Year
Industry data on photovoltaic panel degradation reflects the following general profile for quality monocrystalline panels:
- Year 1: An initial degradation of approximately 2–3% occurs as the panel stabilizes under outdoor operating conditions.
- Years 2–25: Annual degradation of approximately 0.5% per year for premium panels; somewhat higher for lower-grade products.
- At year 25: A premium panel retains approximately 87–90% of its original rated output.
- Beyond year 25: Panels continue to generate electricity at progressively reduced output, typically producing 80–85% of rated capacity at 30 years.
Solergy specifies premium monocrystalline panels with degradation rates at the lower end of the industry range. Annual energy production estimates provided in proposals account for cumulative degradation over the 25-year projection period.
The 25-Year Performance Warranty
All panels installed by Solergy are backed by a manufacturer performance warranty guaranteeing a minimum power output threshold — typically 80–87% of rated capacity — at the end of the 25-year warranty term. If a panel's output declines below the warranted threshold at any point during the warranty period, the manufacturer is obligated to repair or replace the affected panel at no cost to the homeowner.
In practice, premature warranty claims are uncommon. The performance warranty exists as a protection against manufacturing defects or unusual degradation, not as a routine cost management mechanism.
Product Warranty Coverage
Separate from the performance warranty, solar panels also carry a product warranty covering manufacturing defects, physical failures, and workmanship issues. Product warranties for quality panels typically span 10 to 25 years depending on the manufacturer.
Other System Component Warranties
Solar system warranties extend beyond panels:
- Inverter: Manufacturer warranty of 10 years, with extended warranty options available from most manufacturers.
- Mounting hardware: Structural manufacturer warranty, typically 10–25 years depending on manufacturer.
- Installation workmanship: Solergy provides a warranty covering the quality of installation work independently of manufacturer warranties.
Implications for Financial Projections
The gradual nature of panel degradation means that energy production in year 25 is only marginally lower than in year 1. Annual energy projections in Solergy proposals are calculated using degradation-adjusted output over the full 25-year horizon, providing a conservative and accurate basis for financial analysis.