Consumption figures are typical engineering estimates; money figures use the PUCSL tariff effective 11 May 2026. Your exact saving depends on usage hours and which tariff block your extra units fall into — the calculator does this precisely.
What "Inverter" Actually Means
A non-inverter compressor (in an AC, fridge, or washer motor) runs at full power, then switches off, then on again — repeatedly. Every restart draws a spike of power.
An inverter compressor never fully stops — it slows down and cruises, so average draw is typically 30–40% lower for ACs and fridges, and around 30% lower for washing machines.
The catch: inverter models cost more upfront. The real question is whether the electricity saving pays back the price difference — and how fast.
The Numbers — Monthly kWh Used
| Appliance | Non-inverter | Inverter | Units saved/month |
|---|---|---|---|
| AC 9,000 BTU (4 hrs/day) | ~120 kWh | ~78 kWh | 42 kWh |
| AC 12,000 BTU (4 hrs/day) | ~168 kWh | ~108 kWh | 60 kWh |
| AC 18,000 BTU (4 hrs/day) | ~252 kWh | ~162 kWh | ~90 kWh |
| Refrigerator (~10 hrs/day) | ~45 kWh | ~28.5 kWh | 16.5 kWh |
| Washing machine (~0.7 hr/day) | ~10.5 kWh | ~7.4 kWh | ~3 kWh |
What Those Units Are Worth in Rupees
The honest way to value saved units is full bill before minus full bill after — not saved units × one rate. Using fewer units can pull you into cheaper slabs and a lower fixed charge, so the real saving is usually bigger than a quick marginal-rate multiply suggests:
| Monthly household usage | AC 12,000 BTU inverter (saves ~60 kWh) | Fridge inverter (saves ~16.5 kWh) |
|---|---|---|
| ~100 units | 100 → 40 kWh: Rs. 2,328/mo · Rs. 27,939/yr · Rs. 139,693 / 5 yrs | 100 → 83.5 kWh: Rs. 1,036/mo · Rs. 12,431/yr · Rs. 62,154 / 5 yrs |
| ~200 units | 200 → 140 kWh: Rs. 5,836/mo · Rs. 70,031/yr · Rs. 350,154 / 5 yrs | 200 → 183.5 kWh: Rs. 1,692/mo · Rs. 20,308/yr · Rs. 101,539 / 5 yrs |
Computed as whole-bill differences at the May 2026 domestic tariff including the 2.5% SSCL gross-up and slab-dependent fixed charges — the same math the calculator runs.
The heavier your bill, the more inverter saves you. A household already above 180 units pays Rs. 100 for every extra unit — so every unit the inverter saves is a Rs. 100 unit.
Payback Reality Check
- AC (12,000 BTU): inverter premium is typically ~Rs. 40,000–80,000. At Rs. 2,328–5,836/month saved (whole-bill method above), payback is roughly 7 months to 3 years — and 5-year savings can reach Rs. 3.5 lakhs for heavy users.
- Refrigerator: premium ~Rs. 20,000–40,000; payback ~1–3 years; 5-year saving up to ~Rs. 1 lakh.
- Washing machine: smaller saving (~3 kWh/month) — buy inverter for noise/efficiency, not payback.
Try Your Own Numbers
The CEB & LECO bill calculator has an appliance portfolio — add both inverter and non-inverter variants and it shows the monthly / yearly / 5-year difference at your tariff block, not an average.
Official Sources
- Public Utilities Commission of Sri Lanka (PUCSL) — tariff revision approvals and consumer guidance
- Ceylon Electricity Board / Lanka Electricity Company (LECO) — published tariff tables and billing policy
- Electricity Tariff May 2026 Explained — the full rate breakdown this article's figures are computed from
Estimates assume typical usage hours; compressor efficiency varies by model. Always check the appliance's rated watts on its sticker.