Solar Savings Calculator
Calculate your solar panel payback period, annual savings, 25-year return on investment, and CO2 offset. Based on your roof size, location, and local electricity tariff.
Electricity & System Details
Cost & Incentives
Scenario Comparison
| Scenario | Net Cost | Yr 1 Savings | 25-yr Savings | Payback | IRR |
|---|---|---|---|---|---|
| ★ Cash Purchase | $13,084 | $1,800 | $65,478 | 7 yrs | 16.0% |
| Solar Loan Financing | $13,084 | $1,800 | $65,478 | 14 yrs | 8.1% |
| No Solar (utility only) | — | -$1,800/yr | -$70,110 | Never | — |
ROI Analysis & Guidance
- Your 6.2 kW system in CA generates an estimated 10,588 kWh/year using NREL PVWatts methodology (5.82 peak sun hours/day).
- After the 30% federal Investment Tax Credit (ITC), your net cost is $13,084. The ITC applies to installed system costs and is available through 2032 at 30%.
- IRR of 16.0% exceeds most safe fixed-income investments — solar is a strong financial choice in your state.
- Break-even at Year 7 means you have 18 years of pure profit after payback within a standard 25-year panel warranty period.
- Panel degradation of 0.5%/year is factored into each year's production. Premium panels often degrade only 0.3%/year — worth asking installers for degradation warranties.
How to Use the Solar Savings Calculator
- 1
Enter your roof details
Input your available south-facing roof area and roof pitch. These determine how many panels you can install and how much sunlight they receive.
- 2
Select your location
Choose your country or region to apply the correct solar irradiance figure for your latitude and typical cloud cover.
- 3
Enter your electricity tariff
Input your current electricity unit rate (p/kWh). The higher your tariff, the faster the payback period.
- 4
Review ROI and savings
See annual energy generation, annual bill savings, simple payback period, 25-year ROI, and lifetime CO2 avoided.
Key Features
25-Year ROI Projection
See the full financial return over a typical solar system lifetime, including cumulative savings at year 5, 10, and 25.
Location-Based Generation
Uses real solar irradiance data for your region so projections reflect actual sunlight availability rather than generic estimates.
Break-Even Analysis
Calculates the exact year your system pays for itself based on your local tariff, roof size, and installation cost.
Pro Tips
A south-facing roof pitched at 30-40 degrees gives the highest annual generation in the UK. East-west facing roofs generate less but spread production across more hours of the day.
Battery storage significantly improves ROI if you're not home during peak generation hours. Self-consumption rates rise from around 30% to 70%+ with a well-sized battery.
Check eligibility for the Smart Export Guarantee (SEG) - UK energy suppliers must offer a tariff for excess electricity you export to the grid, improving overall returns.
Privacy Note
All calculations run entirely in your browser — no data is sent to any server. Your inputs are never logged, stored, or shared. This tool is completely free with no account or registration required.
Frequently Asked Questions
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