Understanding the 25 year comparison
What the comparison actually shows
For a home starting at $2,400 a year in utility bills with 3% annual rate growth, 25 years without solar costs about $87,502 total. Going solar with a $22,000 system and no federal credit brings the 25 year all-in cost down to about $48,138, a difference of roughly $39,365. The US Department of Energy's homeowner's guide to going solar walks through the same decision step by step.
Why this includes system cost, not just savings
Unlike a savings-only projection, this comparison subtracts your net system cost up front, then adds whatever reduced utility bill remains after your solar savings are applied each year. That gives a true apples to apples total cost figure rather than just a benefit number. See the total cost of ownership calculator for a version that also nets out maintenance and inverter replacement. Utility rates drive the whole savings calculation, and the US Energy Information Administration's electricity data track them state by state.
Why the tax credit default matters here
The 30% federal residential solar tax credit expired for systems placed in service after December 31, 2025. The tool defaults to 0%, accurate for a new purchase in 2026 or later, though you can select 30% if your system was installed by the end of 2025. This changes the net system cost significantly, so double check which rate applies to your situation. The ev charging cost with solar vs grid comparison shows how much extra solar you need once an EV joins the household.
What this doesn't include
This comparison excludes maintenance, inverter replacement, and financing interest. Pair it with the total cost of ownership calculator for a fuller picture, or the payback period calculator to see exactly when the crossover point happens. For a cabin or RV setup, the numbers work differently, and the off grid solar kit cost comparison tool sizes a system for that use.