Solar Payback Calculator

Frequently Asked Questions

How do I estimate annual production?

System size (kW) x 1,200-1,600 kWh/year covers most US locations. NREL's PVWatts calculator gives a precise site-specific estimate for any address.

What does this calculator not include?

Inverter replacement (typically $1,000-$2,000 at year 10-15), annual maintenance ($200-$400/yr), battery storage costs, and the impact of net metering policy changes.

What is panel degradation?

Solar panels lose about 0.5% of output per year due to light-induced degradation and UV exposure. Most manufacturers warrant 80% of rated output after 25-30 years.

Should I add battery storage?

Battery storage adds resilience and can improve self-consumption in low-net-metering areas but extends the solar payback by several years. Factor it as a separate investment.

Provided by AllCalculators.io
Free online calculators for everyday. No registration required.

Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

JavaScript is required to use the interactive calculator above. The questions and answers below remain readable without JavaScript.

How It Works

The calculator computes net system cost after the federal ITC and any state rebate, then models year-by-year savings accounting for annual panel degradation and electricity rate escalation. The break-even (payback) year is the first year where cumulative savings exceed net cost.

Formula: Net cost = system cost × (1 − ITC%) − state rebate. Year-Y savings = annual production × (1 − degradation%)^Y × rate × (1 + rate increase%)^Y. Break-even is found by accumulating savings until they exceed net cost. The 25-year net profit = total 25-year savings − net cost.

Federal Investment Tax Credit (ITC)

The Residential Clean Energy Credit is 30% of the full installed system cost through 2032, including panels, inverter, racking, wiring, and labor. It steps to 26% in 2033 and 22% in 2034 before expiring for residential systems.

The credit is non-refundable - it offsets taxes owed but does not generate a refund. Unused credit carries forward while the credit is in effect. Most homeowners with a tax liability of $3,000-$6,000+ per year use it within 1-2 years.

What Most Affects Payback

In order of typical impact: electricity rate (high-rate states like California and Connecticut see 5-7 year paybacks; low-rate states may see 12-15); solar resource (annual kWh production per kW installed); system cost per watt (national average around $2.85/W installed in 2025); net metering policy (retail vs. wholesale credit for exported power makes a large difference); and state incentives on top of the federal ITC.

FAQ

How do I estimate annual production?

A common rule of thumb is system size (kW) × 1,200-1,600 kWh/year for most US locations, with higher values in the Southwest and lower in the Pacific Northwest. NREL's PVWatts calculator gives a more precise site-specific estimate for any address.

What does this calculator not include?

Inverter replacement (typically $1,000-$2,000 at year 10-15), annual maintenance ($200-$400/yr), battery storage costs, and the impact of net metering rate changes. These reduce actual return.

What is panel degradation?

Solar panels lose about 0.5% of output per year due to light-induced degradation and UV exposure. Most manufacturers warrant 80% of rated output after 25-30 years, consistent with the 0.5%/yr default.

Should I add battery storage?

Battery storage (typically $10,000-$15,000 for a 10-15 kWh system) extends the solar payback by several years but adds resilience against grid outages. In areas with low or no net metering credit for exports, batteries can also improve self-consumption and shorten payback.

Solar Payback Calculator

Frequently Asked Questions

Related Energy & Utilities Calculators