Solar Cost Calculator

Estimate total installed cost from system size and cost per watt. In 2026, residential systems run $1.80–$3.50/W and commercial systems run $0.80–$2.00/W. Gross Cost = System kW × 1,000 × $/W. Cost per watt includes panels, inverter, mounting, labour, permits, and interconnection.

The 30% residential credit (Section 25D) ended for systems completed after December 31, 2025. The commercial 48E credit remains at 30% through 2027, subject to FEOC rules. Net Cost = Gross Cost − Federal Credit − State Credit − Rebates. Always confirm eligibility with a tax professional.

Calculate simple payback with Payback = Net Cost ÷ Year 1 Savings, where Year 1 Savings = Annual kWh × Utility Rate. Model 25-year savings with 0.5%/year panel degradation and 2–4%/year utility rate escalation. 2026 US residential payback runs 6–10 years, with strong markets at 3–6 years.

Estimate LCOE from lifetime costs and lifetime energy production: LCOE = Σ(Lifetime Costs Discounted) ÷ Σ(Lifetime Energy Discounted). 2026 benchmarks: residential $0.04–$0.10/kWh, commercial $0.04–$0.08/kWh, utility-scale $0.02–$0.05/kWh. If LCOE is below the local retail rate, the system has reached grid parity.

Add battery storage to the cost model using $700–$1,300 per kWh installed. Popular 2026 options: Tesla Powerwall 3 at $852–$1,000/kWh, Franklin WH at $778–$926/kWh, Enphase IQ 5P at $900–$1,100/kWh, and Sonnen ecoLinx at $1,000–$1,200/kWh. Include battery cost separately from PV cost.

Generate branded PDF proposals showing system size, cost per watt, gross cost, incentives, net cost, payback, LCOE, battery add-on, and 25-year savings. Include your company branding for client-ready output. Export to CSV for financial models. All calculations run on-device and work offline.