Solar ROI and Payback Calculator
Works out the yearly saving from a solar system and how many years it takes for that saving to pay back the installation cost.
Recent
Formula
How the calculation works
Enter the full installed cost of the solar system in Taka, including panels, inverter, mounting and wiring.
Enter the units the system should generate in a year and your electricity tariff per unit, and the tool multiplies them for the gross yearly saving.
Subtract any yearly maintenance and cleaning cost to get the net annual saving, then divide the system cost by it to get the payback period.
Common mistakes
- Forgetting maintenance and cleaning, which quietly stretches the payback by a year or more over the life of the panels.
- Using the highest slab tariff for all units, when only the units that actually replace grid power are saved at your marginal rate.
When to use it
- Use it before buying a rooftop solar set to see whether the yearly saving justifies the upfront cost in your own tariff bracket.
- Use it to compare two quotes, since a cheaper system can pay back faster even if it generates slightly less power across the year.
Worked example
A system costing 300000 Taka that generates 5000 kWh a year at 8 Taka per kWh with 5000 Taka yearly maintenance saves 35000 Taka a year and pays back in about 8.6 years.
Common questions
Does the payback include the value of exported power?
No, it treats all generation as saving at your own tariff, so if you export surplus units to the grid your real payback will be faster.
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