Solar ROI & Payback, Explained Honestly
Solar is an investment, and every investment deserves real numbers — not inflated promises. Here is how generation, savings, payback, and degradation actually work over a system’s 20+ year life.
The Honest Framing
Payback Is Calculated, Not Promised
Anyone who quotes a fixed “X-year payback” without seeing your bill, tariff, and design is guessing. Real payback depends on your generation, your tariff, and how much of the energy you actually use yourself.
The Five Variables
What Decides Your Return
Generation
How many units (kWh) your system produces per year — driven by capacity, location, orientation, and shading.
Tariff & Self-Use
The value of each generated unit equals the tariff you avoid. The more you self-consume, the higher the saving.
Degradation
Panels lose output slowly — typically a fraction of a percent per year. We factor realistic degradation into long-term estimates.
Maintenance
Cleaning and AMC have a small cost but protect generation. We include them honestly in lifetime value.
Battery (if hybrid)
Batteries add backup value and cost, and are replaced once or twice over the system life. We state this upfront.
The Method
How FSP Estimates Your Payback
Calculate Annual Generation
From your system size, location, orientation, and shading — a realistic kWh/year figure.
Value the Savings
Generation × your tariff, adjusted for how much you self-consume vs export.
Subtract Real Costs
Maintenance, and battery replacement where applicable, over the system life.
Show the Payback Window
System cost ÷ net annual saving — presented as a realistic range, with assumptions you can verify.
Beyond the Numbers
Value That Does Not Fit a Payback Formula
Related Guides
Keep Learning
Get Your Real Numbers
Send your recent bills — we will calculate a realistic generation and savings estimate, with the assumptions shown.