Financial Planning Tools | BlueLine Advisors, LLC — Registered Investment Adviser
Solar Investment Analysis
Quantifying the long-term financial return of residential solar ownership.
System & Cost
Net system cost (after incentives)
Year 1 annual savings ($)
From your installer quote or utility bill
Panel degradation (%/yr)
Baseline: 0.5% — industry standard warranty
Annual maintenance ($)
Baseline: $200 — inverter, cleaning, monitoring
Roof cost at Yr 15 (today $)
Baseline: $5,000 — incremental solar cost
Financial Assumptions
Utility rate inflation (%/yr)
Baseline: 2.5% — NH/New England historical avg
General inflation / CPI (%/yr)
Baseline: 3.0% — above Fed 2% target, recent avg
Hurdle / discount rate (%)
Baseline: 7.0% — conservative equity return
Analysis period (years)
Baseline: 30 yrs — typical panel warranty life
Toggle to model loan payments & their effect on IRR
Down payment ($)
Interest rate (%)Baseline: 6.0% — solar loan avg
Loan term (years)Baseline: 10 yrs — typical solar loan
Down payment ($)
Monthly payment ($)From your lender quote
Loan term (years)Baseline: 10 yrs — typical solar loan
Monthly payment
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Total interest paid
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True cost (principal + interest)
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Adjust inputs to see your result.
Cumulative Cash Flow — Nominal vs. Real
Blue = nominal dollars. Green dashed = inflation-adjusted (real) dollars. Both lines cross zero at their respective breakeven points.
Nominal cumulative CF
Real cumulative CF (CPI-adjusted)
Break-even
Returns & Nominal Breakeven
Real Breakeven (Purchasing-Power)
IRR is the discount rate at which the net present value of all cash flows equals zero, solved via Newton's method on the full series beginning with the negative net upfront cost. Annual savings grow each year at the utility inflation rate net of panel degradation (effective growth ≈ inflation − degradation). Roof cost is inflated from today’s estimate at the utility inflation rate. Nominal breakeven is the year cumulative savings recover the upfront cost in current dollars. Real breakeven deflates each year’s savings by the CPI assumption to show purchasing-power recovery — it always arrives later than the nominal figure. When financing is enabled, annual loan payments are added as a cash outflow through the loan term; IRR is computed on the down payment as Year 0 outlay. This calculator is for illustrative purposes only and does not constitute investment advice.
