LCOE (Levelized Cost of Energy)
Total lifetime cost of a solar system divided by total lifetime electricity produced — the apples-to-apples metric for comparing solar to utility power.
Levelized Cost of Energy (LCOE) is the average cost per kWh of electricity produced over a system's lifetime, calculated as: (Total System Cost + Total O&M Costs – Incentives) ÷ Total Lifetime kWh Produced. It accounts for upfront costs, ongoing costs, panel degradation, and time value of money.
For a typical residential solar installation in 2024: $25,000 gross cost – $7,500 ITC = $17,500 net, with $0 maintenance (panels) plus potential inverter replacement ($1,500 in year 12), producing 350,000 kWh over 25 years at 0.5% annual degradation. LCOE ≈ ($17,500 + $1,500) ÷ 350,000 = $0.054/kWh. The US average retail electricity rate is $0.12–$0.16/kWh — demonstrating solar's economic advantage in most markets.
LCOE comparisons should use a discount rate to account for time value of money. With a 6% discount rate, the same calculation yields a higher LCOE (approximately $0.07–$0.09/kWh) but still favorable against retail rates. LCOE does not capture net metering policy risk — changing export rates affect real financial returns without affecting the production-based LCOE calculation.
Real-World Example
The financial analysis showed the 9 kW system had a lifetime LCOE of $0.061/kWh versus the homeowner's current utility rate of $0.17/kWh — a 64% discount that justified the investment even with a conservative 5% discount rate.