Sid Gangal
build June 25, 2025 · 5 min read

The Solar ITC Cliff: A 50-75% Surge Followed by a 30-40% Demand Drop

Analysis of how the 2025 federal Investment Tax Credit expiration will reshape the U.S. residential solar market with a demand frenzy followed by a significant decline.

solar-energy market-analysis policy

The expiration of the 30% federal Investment Tax Credit (ITC) for residential solar in 2025, with no phase-down as per current Senate and House bill texts, is going to reshape the U.S. solar market. Homeowners are expected to rush installations to lock in the credit, creating a “frenzy” period in 2025, followed by a significant demand drop in 2026. Using updated data and refined assumptions, I estimate a 50-75% demand surge in 2025 and a 30-40% demand decline post-ITC compared to the current 2025 baseline pre-frenzy.

This analysis leverages detailed cost estimates, payback period calculations, and elasticity studies, addressing the nuance of applying price versus payback elasticity to model consumer behavior.

The ITC’s Price Impact: A 43% Cost Increase

A typical 7 kW residential solar system costs approximately $21,000 before incentives, based on 2025 market data averaging $3.03 per watt. The 30% ITC reduces the net cost to:

$21,000 x (1 - 0.30) = $14,700

Post-ITC, the cost reverts to $21,000, increasing out-of-pocket expenses by 43%:

(21,000 - 14,700) / 14,700 = 0.4286 or 43%

This cost jump will challenge affordability, but the pre-expiration rush will drive demand first.

Modeling the Frenzy Period: A 50-75% Demand Surge

When solar incentives face deadlines, homeowners have historically acted swiftly.

  • 2016 ITC Step-Down: The ITC was set to drop from 30% to 10% in 2016 (later extended). In 2015, U.S. residential solar installations grew by ~70% year-over-year, according to the Solar Energy Industries Association (SEIA).
  • Pre-NEM 3.0 Rush in California (2022): Before California’s Net Energy Metering (NEM) 3.0 policy took effect in April 2023, interconnection applications surged by 60-80% in Q3-Q4 2022, per California Energy Commission data.

These patterns suggest a frenzy demand multiplier of 1.5-1.8x (50-80% above baseline). For the 2025 ITC expiration, I model a 50-75% demand surge:

  • Lower Bound (50%): Accounts for supply constraints like installer capacity and equipment availability, which capped some past rushes.
  • Upper Bound (75%): Reflects strong awareness of policy changes, similar to the 2016 and NEM 3.0 surges, assuming robust marketing and consumer urgency.

This surge will inflate 2025 bookings, setting a high baseline before the post-cliff drop.

The Post-Cliff Drop: Price vs. Payback Elasticity

The post-ITC demand drop depends on how the 43% cost increase affects buyer behavior. Economists use price elasticity to measure this, with studies like Gillingham and Tsvetanov (2019) estimating a price elasticity of -0.65 for residential solar, meaning a 1% price increase reduces demand by 0.65%.

Applying this to the 43% cost increase suggests:

0.43 x -0.65 = -0.2795 or approximately, a 28% demand drop

However, homeowners prioritize payback period - the time to recoup costs through energy savings - over sticker price.

Nationally, with an average electricity rate of 16.15 cents/kWh, savings are ~$1,615/year for 10,000 kWh, yielding paybacks of ~9.1 years (with ITC) and ~13 years (without), a 43% increase.

Payback Elasticity: Lessons from NEM 3.0

Price elasticity studies don’t directly measure payback elasticity - how demand responds to payback period changes. California’s NEM 3.0, implemented in April 2023, reduced export rates by ~75%, shifting paybacks from ~6 years to 9-12 years for solar-only systems, a 50-100% increase. Sales dropped 66-83% post-NEM 3.0.

Assuming a 100% payback increase caused an 80% sales drop, payback elasticity is:

-80% / 100% = -0.8

Using the national average 43% payback increase:

0.43 x -0.8 = -34%

Balancing these with the price elasticity estimate (28%), a 30-40% demand drop range is reasonable, with 40% reflecting higher sensitivity in high-rate markets.

Nuances and Assumptions

  • Using price elasticity (-0.65) for payback changes, as in the original analysis, is a simplification, as payback sensitivity is often higher due to psychological barriers (e.g., a 7-8-year payback feels riskier than a 5-year one).
  • NEM 3.0’s -0.8 payback elasticity better captures this, but applying it nationally assumes uniform consumer behavior, which varies by region, electricity rates, and financing options.
  • The 30-40% range accounts for this uncertainty.

Implications for the Solar Industry

The 2025 frenzy requires scaling installer capacity and supply chains to handle a 50-75% demand spike. Post-2026, a 30-40% demand drop necessitates:

  • Financial Planning: 6-9 months of cash reserves to weather the sales valley.
  • Cost Reductions: Sub-$3/kW systems and faster permitting (e.g., 45-day approvals) can mitigate losses.
  • Market Resilience: High electricity rates and long-term savings will keep solar viable, especially in states like California.

This drop is less severe than NEM 3.0’s 66-83% decline, as the ITC cliff affects cost but not ongoing savings as drastically. Companies that prepare for both the boom and bust will gain a competitive edge.

Conclusion

The ITC expiration will drive a 50-75% demand surge in 2025, followed by a 30-40% drop in 2026. These estimates refine the original analysis by using verified costs ($21,000 for 7 kW), corrected payback increases (40-43%), and robust elasticity data (-0.8 from NEM 3.0, -0.65 from studies).

While the drop is significant, solar remains a strong investment, and strategic planning can position companies to thrive.

Disclaimer: This model simplifies complex market dynamics. Regional variations, financing terms, and future incentives may alter outcomes.