How the Solar Payback / ROI Calculator Works
The calculator values the first year's solar energy at the avoided cost per kWh you enter, adds any other annual savings and subtracts annual maintenance. It then projects solar energy with the entered annual degradation rate over the analysis period, adds replacement costs and compares cumulative savings with the initial investment.
Simple Payback vs ROI
Simple payback estimates when cumulative net savings recover the initial solar investment. Simple ROI looks at the total net gain or loss over the selected period relative to the initial investment. These are useful planning indicators but are not the same as discounted cash flow, internal rate of return or net present value.
Choosing an Avoided Energy Cost
The avoided cost should represent what the solar energy actually replaces. A business that mainly offsets generator operation may use a different economic value from a home that mainly offsets grid electricity. Where the power mix changes during the day, a blended or more detailed model may be more appropriate.
Solar ROI in Nigeria
Nigerian households and businesses can use this tool without assuming a fixed national electricity tariff, fuel price or solar-equipment cost. Those values can change and vary by location and use case. Enter the assumptions that apply to the project and use current price information when refining them.
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Frequently Asked Questions
What is solar payback period?
Solar payback is the estimated time required for accumulated net savings from the solar system to recover its initial investment cost.
How is solar ROI calculated?
A simple ROI can be calculated as total net gain over the analysis period divided by the initial investment, multiplied by 100. More advanced investment analysis may use discounted cash flows.
What should I use as the avoided electricity cost?
Use a defensible value for the energy source that solar actually replaces, such as applicable grid electricity cost, generator energy cost or an appropriate blended value.
Does this calculator use current solar prices in Nigeria?
No. You enter the installed system cost. This prevents the calculation from becoming misleading when equipment and installation prices change.
Why does solar degradation matter?
Solar modules can produce slightly less energy as they age. Including a degradation assumption prevents the model from assuming identical annual production forever.
Should battery replacement be included in solar ROI?
If the project uses batteries and replacement is reasonably expected within the analysis period, an appropriate replacement allowance should be included rather than ignored.
Is simple payback enough to make an investment decision?
No. Financing, risk, system quality, energy reliability, future costs, equipment life, warranties and discounted financial measures can also matter.