💰 Solar Yield & Payback Calculator
Estimate annual energy yield, levelized cost of energy (LCOE), simple payback and lifetime net profit from installed capacity, sun hours, performance ratio, tariff and system cost.
💰 Energy & Finance
📊 Yield & Payback
For owners and developers evaluating the economics of a PV system.
How it is calculated
· Annual energy: E = kWp × peak-sun-hours × 365 × PR.
· Lifetime generation: E_total = E × Σ(1 − degradation)^n.
· LCOE = system cost ÷ E_total; payback = cost ÷ annual revenue.
Referenced standards
| Standard | Scope |
|---|---|
| IEC 61724 | Photovoltaic system performance monitoring and analysis |
Worked example — 10 kWp → 11,680 kWh/year
1. 10 kWp, 4 peak-sun-hours, PR 0.80.
2. Annual yield = 10 × 4 × 365 × 0.80 = 11,680 kWh.
3. At $0.12/kWh tariff, annual revenue ≈ $1,402; LCOE and payback follow from your system cost.
FAQ
How is solar payback period calculated?
Simple payback = system cost divided by annual savings. A 10 kW system costing $9,000 that saves $1,200/yr pays back in 7.5 years. Discounted payback also applies a discount rate. The calculator uses 25-year life, 0.5%/yr degradation and local tariff to compute simple payback, IRR, NPV and 25-year net profit.
What LCOE is typical for a residential solar system?
Residential rooftop solar LCOE typically runs $0.06-0.12/kWh depending on irradiation and cost; utility-scale solar reaches $0.03-0.05/kWh. In a 4-5 sun-hour region, a $1,000/kW residential system lands near $0.07-0.09/kWh. The calculator computes full-cost LCOE including O&M, WACC and inverter replacement.
How much does module degradation reduce output over 25 years?
Standard modules degrade about 0.5-0.7% per year, with a first-year drop of 1-2%, giving roughly 85-88% of rated power after 25 years. The calculator applies a 0.5%/yr linear degradation, so year-25 output is about 87.5% of year-1. This materially lowers lifetime LCOE estimates.
What is the difference between P50 and P90 in payback?
P50 payback uses the median year's generation (shorter payback); P90 uses the conservative 90%-exceedance year (longer payback). Lenders underwrite on P90. With 4-6% interannual variability, P90 payback is roughly 1-2 years longer than P50 for a 7-year project. The calculator reports both yield and economics at P50/P75/P90.
Does solar make sense without subsidies?
Yes in most regions. Where module-plus-install costs have fallen to $800-1200/kW and tariffs exceed $0.10/kWh, unsubsidized solar typically pays back in 6-10 years and delivers 10-15% IRR over 25 years. The calculator uses your tariff and system cost to show payback and IRR without assuming any subsidy.
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