Solar Savings Calculator
Estimate annual savings from installing solar panels based on electricity usage and sun hours. Enter values for instant results with step-by-step formulas.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Annual Production (kWh) = System Size (kW) x Peak Sun Hours x 365 x 0.80
Where System Size is the rated capacity in kilowatts, Peak Sun Hours is the average daily hours of peak solar irradiance for your location, 365 converts to annual production, and 0.80 is the system efficiency factor accounting for inverter losses, wiring, temperature, and shading.
Worked Examples
Example 1: Typical Suburban Home Solar Savings
Problem:A homeowner pays $150/month for electricity at $0.13/kWh, installs a 6 kW system for $18,000 with 5 peak sun hours.
Solution:Annual production = 6 x 5 x 365 x 0.80 = 8,760 kWh\nAnnual usage = ($150 / $0.13) x 12 = 13,846 kWh\nSolar offset = 8,760 / 13,846 = 63.3%\nAnnual savings = 8,760 x $0.13 = $1,139\nFederal tax credit = $18,000 x 30% = $5,400\nNet cost = $18,000 - $5,400 = $12,600\nPayback = $12,600 / $1,139 = 11.1 years
Result:Annual savings: $1,139 | Net cost: $12,600 | Payback: 11.1 years | 25-year profit: ~$20,000+
Example 2: High-Rate Area Maximum Savings
Problem:A California homeowner pays $250/month at $0.30/kWh, installs an 8 kW system for $24,000 with 6 peak sun hours.
Solution:Annual production = 8 x 6 x 365 x 0.80 = 14,016 kWh\nAnnual usage = ($250 / $0.30) x 12 = 10,000 kWh\nSolar offset = 14,016 / 10,000 = 140% (excess exported)\nAnnual savings = 10,000 x $0.30 = $3,000 (capped at usage)\nFederal tax credit = $24,000 x 30% = $7,200\nNet cost = $24,000 - $7,200 = $16,800\nPayback = $16,800 / $3,000 = 5.6 years
Result:Annual savings: $3,000 | Net cost: $16,800 | Payback: 5.6 years | 25-year profit: ~$60,000+
Frequently Asked Questions
How much can I save with solar panels each year?
Annual solar savings depend on your system size, local sun exposure, and electricity rates. A typical 6 kW residential system in an area with 5 peak sun hours produces about 8,760 kWh per year after efficiency losses. At the national average electricity rate of $0.13 per kWh, that translates to roughly $1,139 in annual savings. However, savings vary dramatically by location because both sun hours and electricity rates differ. In sunny states with high electricity costs like California and Hawaii, annual savings can exceed $2,000 for the same system size. In cloudy states with cheap electricity like Washington, savings might be closer to $600 to $800 annually.
How many solar panels do I need for my home?
The number of panels needed depends on your electricity consumption, panel wattage, and available roof space. To calculate, divide your annual kWh usage by the annual production per panel. A typical 400-watt panel in an area with 5 peak sun hours produces about 584 kWh per year after efficiency losses. If you use 10,000 kWh annually, you need roughly 17 panels to cover your entire usage. Average US homes use between 10,000 and 12,000 kWh per year, requiring a 6 to 8 kW system or 15 to 20 modern panels. Each panel occupies about 18 square feet of roof space, so 20 panels need approximately 360 square feet of unshaded, south-facing roof area.
How long do solar panels last?
Modern solar panels are designed to last 25 to 30 years and come with performance warranties guaranteeing at least 80% of original output after 25 years. Most panels degrade at a rate of only 0.3% to 0.5% per year, meaning after 25 years they still produce 85 to 92% of their original capacity. Many panels continue producing electricity well beyond their warranty period, with studies showing functional panels still operating after 40 years. The inverter, which converts DC power to AC, typically needs replacement after 10 to 15 years at a cost of $1,000 to $2,000. Panels require virtually no maintenance beyond occasional cleaning and are highly resistant to hail, wind, and temperature extremes when properly installed.
Does net metering affect my solar savings?
Net metering is a billing policy that allows you to sell excess solar electricity back to the grid at the retail electricity rate, and it significantly impacts your total savings. With full net metering, every kWh your panels produce has the same value whether you use it immediately or send it to the grid, maximizing your savings. Without net metering, excess production may be credited at a lower wholesale rate of $0.02 to $0.05 per kWh instead of the retail rate of $0.10 to $0.30 per kWh. Many states are modifying their net metering policies, with some transitioning to time-of-use rates or net billing that values solar exports differently throughout the day. Check your state policies and utility company rules before installing to accurately estimate your financial return.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy