Performance and output

Year 25 output estimator

Enter your stabilized year 1 output and degradation rate. See what your system should produce at year 25, plus total lifetime energy across the whole warranty period.

Your system

1 Project details Optional
Shown on your exported report. Leave blank to skip.
2 Your system
Use your full-year, post-degradation-stabilized annual output as the starting point.
Used to show the dollar value of the year 25 output and lifetime total.
Check your panel's warranty document. Most modern panels fall between 0.3% and 0.6% per year.

How it works

Two steps to your year 25 estimate

Step 1

Start from your year 1 baseline

Take your full-year output once initial degradation has settled. Check the year 10 output estimator first for a mid-point checkpoint. The panel degradation calculator projects how that figure declines over the years.

Step 2

Enter your panel's degradation rate

This figure is usually stated directly on your panel's warranty document, often as a guaranteed maximum degradation curve through year 25 specifically. Compare rates across brands with the output variance by panel brand tool.

Understanding your year 25 output

How much output remains at the 25 year mark

At a typical 0.5% annual degradation rate, a system retains about 88% of its original output at year 25. A system that started at 10,500 kWh/year would still produce roughly 9,263 kWh/year at the 25 year mark. This is a meaningful decline but far from a system that has stopped producing meaningfully. A DOE federal PV performance report uses an age-degradation assumption of about 0.5% per year in its standard performance modeling.

Why year 25 specifically is the reference point

Most manufacturer performance warranties are written to a 25 year term, guaranteeing a minimum output percentage, often around 82% to 85% of original rated output, by that point. Year 25 isn't the panel's expiration date, just the end of the standard guarantee period that most manufacturers use. NLR's PV Fleet data, drawn from thousands of real installed systems, helps establish how actual field performance at this milestone compares against the warranty figures manufacturers publish.

What happens after the warranty period ends

No. Panels typically keep producing well past year 25, often for another decade or more, just at a gradually reduced output level. The 25 year mark reflects the end of the standard warranty term, not the physical end of the panel's useful life. Many systems installed decades ago are still producing usable power today. See the real world vs nameplate output gap calculator for a full picture of all the factors affecting real output at any point in a system's life.

Why the lifetime total matters beyond the single year 25 figure

The year 25 figure shows a single year's output at that point in time, while the lifetime total sums every year of production from year 1 through year 25, which is a more useful figure for estimating total energy value or payback over the system's warrantied life. This total accounts for the gradual decline across all 25 years, not just the endpoint. The 25-year lifetime savings calculator takes that same cumulative approach and turns it into an actual dollar figure.

What to do with this number next

Compare your calculated figures against the year 10 output estimator to see the mid-point checkpoint, or view the complete curve with the 25 year output projection tool.

Questions

Frequently asked

At a typical 0.5% annual degradation rate, a system retains about 88% of its original output at year 25. A system that started at 10,500 kWh/year would still produce roughly 9,263 kWh/year at the 25 year mark.

Most manufacturer performance warranties are written to a 25 year term, guaranteeing a minimum output percentage, often around 82% to 85% of original rated output, by that point. Year 25 isn't the panel's expiration date, just the end of the standard guarantee period.

No. Panels typically keep producing well past year 25, often for another decade or more, just at a gradually reduced output level. The 25 year mark reflects the end of the standard warranty term, not the physical end of the panel's useful life.

The year 25 figure shows a single year's output at that point in time, while the lifetime total sums every year of production from year 1 through year 25, which is a more useful figure for estimating total energy value or payback over the system's warrantied life.

Related tools

Keep exploring your output

Year 10 output estimator First year output estimator 25 year output projection Output variance by panel brand Real world vs nameplate output gap Annual kWh output estimator Performance ratio calculator All performance and output tools