How This Comparison Works

This calculator models two scenarios side by side. In the grid scenario, you pay for all EV charging from the utility at a rate that rises each year due to escalation. The cumulative cost compounds over the analysis period. In the solar scenario, you pay a large upfront installation cost on day one, then cover any gap between your panels' annual output and your EV's annual energy need by buying from the grid. The solar cumulative cost is the install cost plus all those gap charges. The break-even year is when the rising grid cumulative line first crosses the flatter solar cumulative line.

Why Grid Costs Keep Rising

U.S. residential electricity rates have increased at an average of roughly 3 to 5 percent per year for the past two decades. This is driven by aging grid infrastructure requiring expensive upgrades, growing peak demand from electrification, fuel price volatility, and regulatory mandates. A 3% annual escalation rate means the electricity you pay 16 cents per kWh for today will cost about 29 cents by year 20 and 34 cents by year 25. That compounding effect is why EV drivers who lock in solar upfront end up with a significant structural cost advantage over the long term.

The Solar Advantage Compounds Over Time

In the first few years, solar looks expensive because the install cost sits on the books. Grid charging has paid almost nothing yet. As years pass and the grid rate escalates, each additional year of grid charging costs more than the last. The solar cumulative line grows slowly (only gap costs, if any), while the grid cumulative line accelerates. This is why the math typically flips somewhere between years 10 and 14 for most U.S. homeowners post-Section-25D. After that crossover, every additional year of operation increases the solar savings.