Solar Panel Repair vs Replace Cost Calculator
Compare the total cost of repairing your existing solar panels versus replacing them with new ones, factoring in energy savings, panel age, and long-term value.
Formulas Used
Total Replacement Cost:
Total Replace Cost = (Number of Panels × Cost per Panel) + Installation Cost
Annual Savings with Degradation (year t):
Savings(t) = Annual Savings × (1 − Degradation Rate)t
NPV of Savings Stream (Repair — starts from current panel age):
NPVrepair savings = Σ [Annual Savings × (1 − d)(age + t) / (1 + r)t] for t = 1 to (Lifespan − Age)
NPV of Savings Stream (Replace — starts fresh):
NPVreplace savings = Σ [Annual Savings × (1 − d)t / (1 + r)t] for t = 1 to Lifespan
Net NPV:
Net NPVrepair = NPVrepair savings − Repair Cost
Net NPVreplace = NPVreplace savings − Total Replace Cost
Simple Payback Period:
Payback = Upfront Cost / First-Year Savings
Annual Lost Savings Due to Damage:
Lost Savings = Annual Savings × (1 − d)age × Efficiency Loss %
Break-Even Repair Cost:
Break-Even = NPVrepair savings − Net NPVreplace
Assumptions & References
- Average solar panel lifespan is 25–30 years (NREL, 2023).
- Typical panel degradation rate is 0.5%/year (NREL Solar Panel Degradation Study).
- Average replacement cost per panel ranges from $200–$400 installed (EnergySage, 2024).
- Repair costs typically range from $150–$3,000 depending on damage type (HomeAdvisor, 2024).
- Annual energy savings depend on system size, local electricity rates, and sunlight hours.
- Discount rate reflects the opportunity cost of capital or financing rate.
- NPV (Net Present Value) discounts future cash flows to today's dollars for fair comparison.
- Efficiency loss from damage is assumed to be restored to age-appropriate levels after repair.
- Federal Solar Investment Tax Credit (ITC) of 30% may apply to replacement systems (IRS, 2024).
- This calculator does not account for warranty coverage, which may offset repair or replacement costs.