Our Solar & Battery Sizing Calculator returns a specific solar system size (in kW) and battery size (in kWh) matched to your roof, your actual electricity bills and your future plans — along with estimated savings, payback period and CO2 impact. Unlike "enter your postcode, get a generic 6.6kW quote" tools, it models the same variables our consultants assess in person, so the output reflects your property rather than a Sydney-wide average.
Updated August 2026 for NSW residents. Savings and rebate figures reflect incentives current as of August 2026, which step down on a set schedule — confirm current values before quoting.
Quick answer (TL;DR)
- Recommends a precise solar size (e.g. 8.8kW, not a rounded "10kW") and a battery size in kWh.
- Models your roof orientation, shading, bills, tariff and future EV/pool/air-con plans.
- Returns savings, simple payback, 10-year ROI and estimated CO2 avoided.
- Applies August 2026 incentives: STCs, Federal Cheaper Home Batteries Program, NSW PDRS.
- A strong starting point for a consultation — not a locked-in quote.
Oversize the solar array and you're paying for panels that clip output on sunny days and export at rock-bottom feed-in tariffs. Undersize the battery and you're still buying peak-rate power every evening. This calculator solves that properly.
You'll enter your postcode (solar irradiance varies meaningfully between coastal Wollongong and inland Bathurst or Orange), along with your roof type, orientation (north, east, west or a split-roof combination), pitch, and any shading. A west-facing roof with afternoon shading behaves very differently to an unshaded north-facing roof, and the calculator weights its recommendation accordingly.
Next comes your quarterly bill amount and tariff type — flat rate, time-of-use, or controlled load. If you're on a time-of-use tariff with expensive 3pm–9pm peak pricing, the tool will typically lean towards a larger battery to shift more of your usage away from those peak windows.
This is a step most calculators skip. We ask whether you're planning to buy an EV, install a pool or add reverse-cycle air conditioning in the next 1–3 years. An EV alone can add 3,000–4,500kWh of annual demand, so factoring it in now avoids a system that's already undersized the day it's commissioned.
A specific kW recommendation (for example, 8.8kW or 13.3kW rather than a rounded "10kW"), along with the panel configuration that achieves it and why that size is the sweet spot for your situation.
A battery size recommendation in kWh, matched against your evening and overnight usage. For most Sydney households this lands between 10kWh and 20kWh. The tool suggests whether a DC-coupled hybrid option (Sigenergy, Goodwe, Fox ESS or Sungrow) or an AC-coupled retrofit approach suits your situation — an AC-coupled retrofit is the right call if you already have solar and don't want to touch your existing inverter.
The calculator projects your estimated annual bill savings, simple payback period, and return on investment over a 10-year horizon, using current NSW electricity tariffs and feed-in rates. It factors in the incentives available in August 2026 — the federal Cheaper Home Batteries Program (roughly $272/kWh for the first 14kWh, $163/kWh for the next 14kWh, tapering to around $41/kWh from 28–50kWh), the NSW PDRS battery incentive (up to $1,100–$1,500 upfront), and the STC discount on new solar (typically $2,000–$2,500 off a standard 6.6kW system). Because both federal and state battery incentives step down periodically, the estimate reflects today's rates specifically.
We translate your projected annual generation into an estimated tonnes of CO2 avoided per year, based on the current NSW grid emissions factor.
Finally, the calculator suggests a specific panel and battery pairing from our premium product range, matched to your budget tier and priorities — whether that's maximum lifetime output, best blackout protection, or the lowest total installed cost within our no-cheap-imports standard.
A system sized 20% too small leaves real savings on the table every quarter for 10–25 years. A system sized 20% too large means you've paid for capacity you'll rarely use. Getting the size right the first time is the single highest-leverage decision in the entire process — more important than which brand you eventually choose.
Your results aren't a locked-in quote — they're a strong starting point for a conversation with one of our Sydney-based consultants, who can refine the recommendation after reviewing your roof photos or visiting in person.
(Figures current as of August 2026 — these incentives step down on a set schedule; confirm current values before quoting.)
Run the Solar & Battery Sizing Calculator now and see your personalised recommendation in minutes, or call 0421 458 217.
