Solar Panel for Home Calculator
All-in-one home solar estimator. Calculate system size, cost before and after incentives, 25-year savings projection with panel degradation and rate increases, ROI, and CO2 offset.
25-Year Savings Projection
Includes 0.5% annual panel degradation and 3% annual electricity rate increase.
| Year | Production (kWh) | Annual Savings | Cumulative |
|---|---|---|---|
| 1 | 6,711 | $1,873 | -$6,947 |
| 2 | 6,678 | $1,920 | -$5,027 |
| 3 | 6,644 | $1,967 | -$3,060 |
| 4 | 6,611 | $2,016 | -$1,044 |
| 5 | 6,578 | $2,067 | $1,023 |
| 6 | 6,545 | $2,118 | $3,141 |
| 7 | 6,512 | $2,170 | $5,311 |
| 8 | 6,480 | $2,225 | $7,536 |
| 9 | 6,447 | $2,280 | $9,816 |
| 10 | 6,415 | $2,336 | $12,152 |
| 11 | 6,383 | $2,394 | $14,546 |
| 12 | 6,351 | $2,454 | $17,000 |
| 13 | 6,319 | $2,515 | $19,515 |
| 14 | 6,288 | $2,578 | $22,093 |
| 15 | 6,256 | $2,641 | $24,734 |
| 16 | 6,225 | $2,707 | $27,441 |
| 17 | 6,194 | $2,774 | $30,215 |
| 18 | 6,163 | $2,843 | $33,058 |
| 19 | 6,132 | $2,914 | $35,972 |
| 20 | 6,102 | $2,987 | $38,959 |
| 21 | 6,071 | $3,061 | $42,020 |
| 22 | 6,041 | $3,137 | $45,157 |
| 23 | 6,011 | $3,215 | $48,372 |
| 24 | 5,980 | $3,294 | $51,666 |
| 25 | 5,951 | $3,377 | $55,043 |
How It Works
This comprehensive calculator estimates your complete home solar investment:
- Energy estimation: Your monthly electric bill is converted to kWh using your state's average electricity rate. This determines how much energy your solar system needs to produce.
- System sizing: Required system size accounts for your state's peak sun hours, shade level, and 80% system efficiency (losses from inverter, wiring, temperature, and soiling).
- Cost calculation: Total cost uses the national average of $3.00/watt installed. The 30% federal ITC is applied to determine net cost.
- 25-year projection: Annual savings are calculated with 0.5% panel degradation per year and 3% annual electricity rate increases. Cumulative savings show when the system pays for itself.
- CO2 offset: Environmental impact is calculated at 0.855 lbs of CO2 per kWh, the U.S. grid average.
Frequently Asked Questions
How much does a home solar system cost in 2025?
The average residential solar system costs $2.50-$3.50 per watt installed. A typical 8 kW system costs $20,000-$28,000 before incentives. The 30% federal Investment Tax Credit (ITC) reduces this by 30%, bringing the net cost to $14,000-$19,600. State and local incentives may reduce costs further.
How does roof shading affect solar production?
Shade significantly reduces solar panel output. Light shade (occasional tree shadows) reduces production by about 5%. Moderate shade (partial coverage for several hours) reduces it by 15%. Heavy shade (significant tree or building coverage) can reduce output by 30% or more. Consider tree trimming or microinverters for partially shaded roofs.
What is the typical payback period for home solar?
Most residential solar systems pay for themselves in 6-10 years through electricity savings. After payback, you essentially get free electricity for the remaining 15-19 years of the panel warranty. States with higher electricity rates (like California, Connecticut, and Hawaii) see faster payback periods.
How does panel degradation affect long-term savings?
Solar panels typically degrade at about 0.5% per year, meaning after 25 years they still produce about 87.5% of their original output. However, rising electricity rates (averaging 3% annually) more than offset this degradation, so your dollar savings actually increase each year.
Does my roof type affect solar panel installation?
Yes. Asphalt shingle roofs are the easiest and cheapest to install on. Metal roofs work well with clamp mounts and require no drilling. Tile roofs need special brackets and cost more to install. Flat roofs use tilt-mount systems that add some cost but allow optimal panel angles.