Cumulative savings vs. net system cost — curves cross at break-even
Cumulative savings
Net system cost
Break-even
▶ 25-year net profit (cash):
Scenario ComparisonAll Options
* Estimates only. Costs and savings vary by installer, utility, permitting and performance. Consult a licensed solar installer for a formal proposal. The federal 30% ITC was eliminated July 2025 for new residential installs.
Assumptions & Methodology
Panel efficiency20% (standard residential)
Roof: Small300 sq ft (~4.6 kW max)
Roof: Medium500 sq ft (~7.7 kW max)
Roof: Large800 sq ft (~12.3 kW max)
Roof: Very large1,200 sq ft (~18.5 kW max)
Base install cost$2.85/W national avg
Labor costState-indexed (18–32% of total)
Battery (CA)~$4,000 (single unit, state avg)
Battery (other states)~$7,000–$10,000
Federal ITC (2025)Eliminated July 4, 2025 for new installs
State incentivesUser-selected tiers, not modeled by state
Sun hoursDerived from state avg peak sun
System degradation0.5% per year
Electricity rate inflation2.5% per year
O&M cost (years 11–25)$150/year
Default loan APR6.5%
State cost multipliers, labor rates, and sun hours derived from regional data. For educational estimation only.