It compares the initial investment with projected net savings across the selected period. Read ROI together with the payback year and annual cash flow: maintenance and equipment replacement can change when the investment is recovered. This model uses your assumptions and does not guarantee a financial return.
計算方法
Year-one savings = monthly savings × 12. Subsequent savings grow by (1 + growth) × (1 − degradation) each year. Deduct annual maintenance and any replacement in its specified year. Payback is the first year-end after which cumulative cash flow remains nonnegative through the selected horizon. ROI = net profit ÷ upfront cost.
Undiscounted cash-flow estimate; no financing, taxes or residual value. Savings growth is an assumption, not a forecast. Monthly savings should already account for self-consumption, exports and bills that remain payable. Replacement costs are treated as year-end costs.
Is payback guaranteed?
No. It changes with production, tariffs, self-consumption, equipment costs and maintenance.
