How do I calculate solar panel payback period?

The payback period is calculated by dividing the net system cost (after incentives) by annual energy savings. Our calculator considers Federal ITC (30%), state rebates, electricity rate escalation, and panel degradation for accurate results.

What is the Federal Investment Tax Credit (ITC) for solar?

The Federal ITC provides a 30% tax credit for solar systems installed through 2032. It steps down to 26% in 2033 and 22% in 2034. Our calculator automatically applies this credit based on your installation year.

How accurate is the solar production estimate?

Our calculator uses NREL PVWatts methodology with region-specific peak sun hours, panel efficiency data, and system derate factors. Production estimates are typically within 5-10% of actual output.

What is NPV and why does it matter for solar?

Net Present Value (NPV) accounts for the time value of money - a dollar today is worth more than a dollar in 25 years. A positive NPV means your solar investment creates real value when accounting for inflation and opportunity cost.

What is a good IRR for solar investment?

An IRR above 10% is considered excellent for solar investments. IRRs of 6-10% are good, and anything above your alternative investment returns (like stocks at ~7-8%) makes solar financially attractive.

How does net metering affect my payback?

Full retail net metering (1:1 credit) provides the best returns - excess solar goes back to the grid at full retail rate. Reduced net metering policies decrease ROI by crediting exports at lower rates.

Should I finance or pay cash for solar panels?

Cash purchases typically provide the best ROI since you avoid interest costs. However, low-interest solar loans can improve cash flow while still providing positive returns, especially when loan payments are less than monthly savings.

Solar Panel Payback Calculator

Calculate your solar panel investment ROI with NPV, IRR, and payback period analysis. Uses NREL PVWatts methodology for accurate production estimates. Includes Federal ITC (30%), state incentives, financing options, and 25-year cash flow projections.

NREL PVWattsITC 30%25-Year AnalysisNPV & IRR

Solar Payback Calculator

Enter your system details to calculate payback period and financial returns

System Specifications

System Size (kW)

Total DC capacity of your solar panel system

Panel Type

Different technologies have varying efficiency and degradation rates

Geographic Region

Region affects peak sun hours and production estimates

Installed Cost per Watt

Total installed cost including equipment and labor (national avg: $2.50-$4.00/W)

Electricity & Rates

Monthly Electricity Bill

Your average monthly electricity bill

Electricity Rate (per kWh)

Your current electricity rate (US average: $0.12-$0.30/kWh)

Annual Rate Escalation

Expected annual increase in electricity rates (historical avg: 2-4%)

Net Metering Policy

How your utility credits excess solar production

Tax Credits & Incentives

Apply Federal ITC

Federal Investment Tax Credit - 30% through 2032, steps down after

Federal ITC Rate

30% for systems installed 2022-2032

State/Utility Rebate

One-time rebate from state or utility company

State Tax Credit

State tax credit as percentage of system cost

Financing Options

Financing Method

How you plan to pay for the system

Advanced Analysis Options

Analysis Period (years)

Standard solar panel warranty period is 25 years

Discount Rate

For NPV calculation (typically 4-7% for residential)

Include Inverter Replacement

Inverters typically need replacement after 10-15 years

Custom Panel Degradation Rate

Annual degradation rate (leave empty to use panel type default: mono 0.4%, poly 0.5%, thin-film 0.7%, bifacial 0.35%)

About Solar Payback

This calculator uses NREL PVWatts methodology to estimate solar production and comprehensive financial modeling including NPV, IRR, and cash flow analysis.