Understanding your output decline table
Why a year-by-year view is useful
A single endpoint figure, like expected output at year 25, tells you where you'll end up but not how you got there or what to expect at any point along the way. A full year-by-year table lets you check your system's actual monitored output against expectations at any given year, not just at the far end of the warranty period, making it a more practical reference for ongoing system health tracking. The annual kWh output estimator fills in the actual production numbers this table leaves out.
Why the annual dollar or watt loss shrinks slightly each year
Since degradation compounds as a percentage of the previous year's already-reduced output, the actual watt amount lost each year gets slightly smaller over time even though the percentage rate itself stays constant. This is a subtle but real distinction from a simple linear decline, and it's part of why degradation curves flatten out slightly rather than declining in a perfectly straight line, a shape worth visualizing directly in the 25 year degradation curve tool. For a plain-language explanation of degradation and warranties, the Department of Energy's homeowner's guide to going solar is worth reading.
What this table doesn't capture
Degradation is permanent and gradual, but real-world output also fluctuates from year to year due to weather variation, temporary soiling buildup, and seasonal differences in sun angle and daylight hours. None of those temporary factors are reflected in this table, which is why comparing a single year's real output against this modeled curve can be misleading, tools like the cleaning ROI tool address the soiling piece specifically. For a more general introduction to keeping a system performing well over time, the Department of Energy's guide to operating and maintaining a PV system is worth a read.
Using this table for financial planning
If you're modeling long-term solar savings, a year-by-year output table feeds more accurately into that calculation than a single degraded endpoint applied uniformly across all years. Multiply each year's output figure by your expected electricity rate for that year to build a more precise savings projection than a flat-rate estimate would provide, similar to the approach used in the maintenance cost vs savings net calculator. If declining output changes how a solar loan pencils out over time, the zero down loan total cost calculator is a useful companion.