The solar panel degradation calculator shows how your system's output will decline year by year as panels age. All solar panels lose efficiency over time — the rate depends on panel type, climate zone, and manufacturing quality. Use these projections to estimate lifetime energy production and compare against your manufacturer's 25-year warranty guarantee.
System Parameters
Check your installer's estimate or utility bill
Output Degradation Curve
Dashed line = typical 80% performance warranty at year 25. Your panel output should stay above this line to remain within warranty.
Year-by-Year Projection
| Year | Calendar Year | Annual Output | Efficiency | Cumulative kWh | Warranty Status |
|---|
How to Use the Solar Panel Degradation Calculator
Solar panels don't produce the same output forever. Every year, gradual chemical and physical changes reduce power output by a small percentage. This solar panel degradation calculator lets you project exactly how much energy your system will generate over its lifetime — and whether it will stay within warranty bounds.
Step 1: Enter Your System Size
Input your installed system capacity in kilowatts (or watts). A typical residential system is 4-10 kW. You can find this on your original installer quote, utility interconnection agreement, or monitoring portal. Toggle between kW and watts using the unit selector.
Step 2: Select Your Panel Type
Panel type is the biggest factor in degradation rate. Premium monocrystalline panels (like SunPower and LG) degrade only 0.30% per year — after 25 years you still have 93% of original output. Standard monocrystalline (most common, including Canadian Solar, Jinko Tier 1) degrade at 0.45%/yr. Polycrystalline panels are older technology and degrade faster at 0.55-0.70%/yr.
Step 3: Enter First-Year Output
Your first-year production estimate comes from your solar installer's proposal or your actual utility bills from year 1. It accounts for your location's solar irradiance, roof tilt, panel orientation, and any shading losses. If you don't have this number, a rough estimate is: system size (kW) × 1,200-1,600 hours of peak sun per year.
Step 4: Select Your Climate Zone
Hot climates accelerate degradation through thermomechanical stress. The Phoenix/Las Vegas desert southwest experiences ~20% faster degradation than manufacturer specs (which are typically tested in mild laboratory conditions). The Pacific Coast and Northern states see close to nominal rates.
Understanding the Warranty Line
The chart shows a dashed line at 80% of original output — the industry-standard performance warranty threshold at year 25. If your projected output falls below this line before year 25, you may have grounds for a warranty claim. Premium panels from SunPower and Panasonic now offer 87-92% guarantees at year 25.
Using the 25-Year Projection
Lifetime energy production is the key metric for solar ROI calculations. Divide your total installation cost by the 25-year cumulative kWh to get your levelized cost of energy (LCOE). Compare this against your current utility rate to see your true payback. For a 6 kW system producing 8,000 kWh in year 1, expect roughly 183,000-195,000 lifetime kWh depending on panel type.
FAQ
Is this solar panel degradation calculator free?
Yes, completely free with no signup required. All calculations run in your browser.
What is solar panel degradation?
Solar panel degradation is the gradual reduction in power output over time due to UV exposure, thermal cycling, and material aging. Industry standard degradation rates are 0.3-0.7% per year, meaning a panel rated at 400 watts today will produce slightly less power each year.
How much do solar panels degrade per year?
Premium monocrystalline panels degrade about 0.3-0.5% per year. Standard polycrystalline panels degrade at 0.5-0.7% per year. This means after 25 years, a quality monocrystalline panel still produces 88-93% of its original output, while polycrystalline panels produce 83-89%.
What does the 25-year performance warranty mean?
Most solar manufacturers guarantee 80% of rated output at year 25 (some premium brands guarantee 87-92%). If your panel is producing less than the guaranteed minimum, the manufacturer is obligated to repair or replace it. Our calculator compares your projected output against this 80% warranty line.
Does heat accelerate solar panel degradation?
Yes — hot climates experience faster degradation than temperate ones. The primary mechanism is thermomechanical stress from daily temperature cycling. Desert installations (Phoenix, Las Vegas) may degrade 10-20% faster than the manufacturer's stated rate, while mild coastal climates see closer to the nominal rate.
How much energy will my solar system produce over 25 years?
Use this calculator to get a precise estimate. As a rough guide, a 6 kW system producing 8,000 kWh in year 1 will generate approximately 185,000-195,000 kWh over 25 years after accounting for degradation — roughly $18,000-25,000 worth of electricity at current US average rates.