Singapore Solar & Battery Payback Calculator

Your monthly bill is converted to annual consumption at the live SP Group tariff. A system is then sized to generate about 70% of that consumption (90% if you add a battery) at Singapore's typical solar yield of ~1,150 kWh per kWp per year, capped by what your roof type can physically fit. Energy you use on-site displaces the full tariff; surplus exports earn Simplified Credit Treatment (SCT) credits at the regulated tariff minus grid charges — about 28.1 cents/kWh including GST at the current tariff, recalculated automatically whenever SP revises the tariff. Savings can never exceed what the sized system actually generates.

Without a battery, surplus midday solar exports at about 28.13 cents/kWh. Every kWh a battery keeps for the evening is worth about 6.65 cents more than exporting it. It can do this once a day, and only up to its size: 20 kWh, or 40 kWh as two units.

It is a planning estimate built on published data: the live SP tariff, EMA wholesale statistics, and Sunollo's published package pricing. Your actual number depends on roof orientation, shading, and your consumption pattern — a free on-site assessment gives you a firm quote, and Sunollo's SunolloCare savings guarantee backs the delivered performance.

Fair question — Sunollo installs solar, so we have an interest in the answer. That's exactly why nothing here is hidden: every rate, yield, and price is listed below with a source you can check yourself, the tariff comes from a public CC-BY-licensed API, and savings are hard-capped by what a system can physically generate on your roof type. The calculator also shows unflattering answers honestly: a small bill on a big package gets a long payback, and if your roof can't cover your usage, it says so. If you think an assumption is wrong, the methodology is right here to argue with.

Yes, free. Click "Embed this calculator on your site" above and copy the snippet. The embed auto-sizes to fit your page, always uses the current quarter's SP tariff, and never goes stale. Publishers and partners can add a partner tag so leads from their site are credited to them.

• SP Group regulated tariff: 34.78 cents/kWh incl. 9% GST (Q3 2026), fetched live from the Sunollo Real Tariff Index (CC-BY-4.0) and updated every quarterly SP revision. From Q3 2021 to Q3 2026 the tariff before GST rose from 23.38 cents to 31.91 cents, about 6.4% a year. The line under the payback uses that pace as a continuation, and says so.
• Yield: ~1,150 kWh per kWp per year, Singapore's typical average. Panels are 665 W (~3.1 m² each); auto-sizing targets your property's typical roof capacity, with an outer limit for larger-than-typical roofs available via "Adjust system size."
• Self-consumption: ~60% of generation used on-site without a battery, based on Sunollo fleet data. A battery keeps extra surplus, once a day, up to its size and up to what the home still buys. Surplus that is still exported is credited under Simplified Credit Treatment (SCT), which EMA sets at the regulated tariff minus grid/network charges: 34.78¢ ÷ 1.09 − 6.10¢ = 25.81¢ before GST, or 28.13¢ including GST. Derived from the live tariff, so it never drifts. See the electricity plan comparison for the SCT-versus-ECIS difference if you switch retailer.
• Singapore's wholesale market (EMA/NEMS data) averaged S$185/MWh across the 10am–4pm solar export window and S$472/MWh in the 7–11pm evening peak over the 60 days to 10 Sep 2026 — evening energy cost 155% more. That gap is why shifting midday surplus into the evening has value at all. A home on the regulated tariff pays a flat rate rather than the wholesale price, so what it actually captures is the narrower tariff-minus-SCT spread used above, not the wholesale spread.
• Costs from Sunollo's published pricing: packages from an S$14,500 floor, ~S$1,000–S$1,200 per kWp for larger systems. A 20 kWh battery is S$10,000. A 40 kWh battery is two of those units, S$20,000. SCDF Fire Code clause 10.3.5 allows that in a landed house when the units are at least 1 m apart. It takes effect on 1 March 2027.