Understanding your 30 year projection
What five extra years add
Starting from $1,800 in year-one savings, with 3% annual utility rate growth and 0.5% annual panel degradation, total savings reach about $78,836 over 30 years, compared to $61,365 over 25 years. Those last five years alone contribute roughly $17,470, since your savings have grown substantially by that point in the projection. The US Energy Information Administration's electricity data show how retail rates have moved, which is the starting point for any savings estimate.
Do panels actually last 30 years?
Most manufacturers only warranty performance through 25 years, but the panels themselves typically keep producing well past that point. At a 0.5% annual degradation rate, output at year 30 is still around 85% of the original figure, which is why this longer projection remains realistic for homeowners planning to stay in place. For the official overview, the US Department of Energy's homeowner's guide to going solar covers buying, leasing, and system sizing.
Choosing between the 25 and 30 year view
The 25 year figure aligns with manufacturer warranties and is the more conservative choice. The 30 year figure gives a fuller picture if you're confident you'll stay long term. Compare both directly using the 25 year lifetime savings calculator. The bifacial panel output addon calculator is the quickest way to check whether the system size behind this estimate fits your roof and usage.
What this projection leaves out
This is a savings-only figure and doesn't account for inverter replacement, which most systems need once or twice over a 30 year span. Check the inverter replacement cost tool for a version that nets that expense out, or the total cost of ownership calculator for the fullest picture. If your production estimate feels uncertain, the real world vs nameplate output gap calculator gives you a second check on annual output.