Clean Energy · Quick Answer
How do you calculate solar payback?
Solar payback = (system cost − incentives) / annual electricity savings. For a $20,000 system with a $6,000 tax credit saving $1,800/year, payback = $14,000 / $1,800 = 7.8 years.
The formula
Payback years = (System Cost − Tax Credits − Rebates) / Annual Savings
Example: 8 kW rooftop system
- Gross cost: $20,000
- 30% federal ITC: −$6,000
- State rebate: −$500
- Net cost: $13,500
- Annual generation: ~11,000 kWh
- Electricity rate: $0.16/kWh
- Annual savings: 11,000 × $0.16 = $1,760
- Payback: 13,500 / 1,760 = 7.7 years
What affects payback
Shortens payback
- High local electricity rates (CA, MA, NY, HI)
- Net metering at full retail rate
- Strong solar resource (AZ, CA, TX sun belt)
- Federal ITC at 30%
- Time-of-use plans that align with solar generation
Lengthens payback
- Low electricity rates (Pacific Northwest, Appalachia)
- Poor orientation or shading
- Net billing at wholesale rate (CA NEM 3.0)
- Financing with high interest (loan interest eats into savings)
Total lifetime savings
A panel system typically lasts 25+ years with 0.5% annual degradation. After payback, years 8-25 are effectively free electricity. Lifetime savings typically range from $20,000-$60,000 on residential systems, depending on utility rates.
Cash vs. loan vs. lease
- Cash: best ROI; shortest payback
- Solar loan: you own the system and get the tax credit; payback extends 2-4 years
- Lease / PPA: no upfront cost but you don't own the system or get the tax credit; savings are modest (10-20% of the bill)
Run the numbers
All calculators →Solar Payback Period Calculator
Calculate how many years it takes for your solar investment to break even.
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Estimate how much electricity a solar panel system generates and how much money it saves you.
Solar Savings Calculator
Calculate how much money you save over the lifetime of a solar panel system.