Solar vs Grid Calculator
Compare the 25-year cost of solar vs staying on the grid. See exactly when solar pays off and how much you save total.
| Year | Grid cost | Solar savings | Net position |
|---|---|---|---|
| Yr 1 | $1,800 | $1,800/yr | $15,700 |
| Yr 5 | $9,459 | $1,986/yr | $8,041 |
| Yr 9 ★ | $17,907 | $2,191/yr | +$407 |
| Yr 10 | $20,152 | $2,245/yr | +$2,652 |
| Yr 15 | $32,242 | $2,538/yr | +$14,742 |
| Yr 20 | $45,911 | $2,870/yr | +$28,411 |
| Yr 25 | $61,365 | $3,244/yr | +$43,865 |
How to Use This Calculator
Enter system cost and tax credit
Enter the gross system cost — the total installed price before any incentives. Get this from installer quotes; US residential averages $2.50-3.50/W in 2026, so an 8kW system typically costs $20,000-28,000. The federal tax credit defaults to 30% (valid through 2032). Enter the percentage as a decimal — 0.30 for 30%. If your state offers additional credits, add them here.
Set your electricity rate and annual increase
Use your current electricity rate from your utility bill. The annual rate increase is the key long-term variable — historically US electricity prices have risen 2-4% per year. A higher rate increase makes solar more valuable: at 4%/year, electricity costs double in 18 years. At 2%/year, it takes 36 years. This is why solar looks better in high-rate states with rising prices.
Enter annual solar production
Use the Solar Panel Calculator to estimate your system's annual kWh production. A typical 8kW system produces 9,000-13,000 kWh/year depending on location. The panel degradation of 0.5%/year accounts for natural efficiency decline — standard panel warranties guarantee 80% output after 25 years (0.8% degradation/year), making 0.5% a conservative estimate.
The Formula
The crossover year (payback period) is when your cumulative savings equal your net investment. After that, every dollar of savings is pure return. For most US homeowners, the crossover is 6-10 years. In high-rate states like California, Massachusetts, and Hawaii, crossover can be as short as 4-6 years.
Example
The Williams family — Denver, Colorado
The Williams family installs an 8kW system for $24,000. After the 30% ITC, they pay $16,800. Denver gets good sun — 11,500 kWh/year. They currently pay $0.14/kWh and electricity rates rise 3%/year.
25-year result
The Williams family breaks even in year 8 and earns $41,600 in net savings over 25 years — a 248% return on their net investment of $16,800. That's significantly better than a savings account or bond over the same period, with no market risk. The grid electricity they avoid paying for keeps rising in cost every year, making solar savings grow over time.