Understanding your capacity fade table
Why a full table beats a single-year answer
A single projected figure at year 10 tells you where you'll end up, but not how you got there or what happens in between, a shortcoming NREL's energy storage research addresses by modeling degradation as a continuous curve rather than a single checkpoint. A full table lets you check any specific year against a warranty term, a resale timeline, or a planned system upgrade, all from the same set of inputs.
Reading the shape of the curve
Because this model applies a constant percentage loss to whatever capacity remains, the real kWh lost each year shrinks over time even as the percentage rate holds steady. Early years lose more absolute capacity than later years, the same declining-loss shape covered in the 25 year degradation curve tool, which is worth keeping in mind if you're using the capacity over time calculator to sanity-check a single point on this same curve.
Where the model gets less reliable
The first several years of this table tend to track real-world results reasonably well, but further out the model can't capture manufacturing variance, changing usage patterns, or the accelerated fade some batteries show near the end of their rated cycle life, the same forecasting difficulty NREL's Battery Lifetime Analysis and Simulation Tool suite is built to narrow with fuller thermal and usage data. The state of health calculator is a good way to check an existing battery against the table's assumptions. Treat later years as a general planning range rather than a precise forecast.
What to check next
Once you've reviewed the full table, the replacement timing tool turns your chosen threshold year into a real calendar date for budgeting. For a second, independent check on that date, the battery storage size calculator in our Battery & Storage section can help you confirm the bank still meets your daily load at that age.