Solar Rooftop Payback
How much a rooftop solar system saves on your electricity bill each month, and how many years it takes to pay for itself.
Worked out on the normal home meter tariff. If you have a time-of-use meter or solar panels already, treat this as a rough guide.
The generation figure is an estimate — weather, shade and which way the panels face all change it.
Your system makes more than your home uses (600 kWh made, 120 kWh used). The extra power is not counted here — this version only counts what you stop buying from the grid.
Electricity bill from the PUCSL tariff (Annex-2, 11 May 2026). Solar generation is an estimate, not a promise.
Trip fuel cost from distance, mileage and pump price.
EV trip cost from distance and your own kWh/100km, with home vs public charging and a petrol comparison.
CEB or LECO bill from units used, with the block-by-block breakdown. PUCSL tariff, 11 May 2026.
Questions
About 120 kWh a month at 4 sun hours a day (1 kW × 4 hours × 30 days). A sunny month gives a bit more, a cloudy month a bit less.
The saving can never be more than your whole electricity bill. If the system makes far more than your home uses, the extra power is wasted in this simple version — it does not count selling power back to the grid.
No. This version only counts the bill you stop paying. If you export power under net metering or net accounting, your real saving is higher and the payback is shorter.
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