Find Your Right Size
Solar System Size & Savings Calculator
Know your system size before you ring a quote.
Your estimate · Adelaide
- Suggested size
- 3.5 kW
- nearest standard size 6.6kW
- Yearly generation
- 5,289 kWh
- 1511 kWh per kW (Adelaide)
- Yearly saving
- $813
- 30% used at home
- STC discount (included in most quotes)
- $912
- 24 STCs
- Payback
- 7.1 years
- on $5,750 system price
Estimates with stated assumptions, not a quote. Local values come from the data layer (Adelaide). Incentives: Small-scale Technology Certificates (STCs) under the federal SRES, the federal Cheaper Home Batteries Program (from 1 July 2025) and any state rebates. Amounts change on set dates, so always confirm current figures with the CER or your state energy agency.
Get exact quotes for my homeHow do I work out what size solar system I need?
System size depends on your annual power consumption and how much roof space you have. Start with your last 12 months of electricity bills and find your total kWh used; divide by 365 to get daily average consumption, then divide by peak sun hours in your state (typically 4–5 hours per day) to estimate the kilowatts you need. Most Australian homes fit a 5–10 kW system; larger households or those who charge an electric vehicle may need 10–15 kW or more. Solar Advice's site assessment includes a roof check and shading analysis so the final design matches both your consumption and your roof.
What roof factors change the size I can install?
Roof pitch, material, number of storeys, shading from trees or buildings and available unshaded space all set your maximum system size. A north-facing, steep tile roof in full sun can hold 12+ kW; a flat roof, skylights or afternoon shade from neighbours may limit you to 4–6 kW. Asbestos cement or old metal roofing may need a roof survey before install. During a site assessment, Solar Advice's accredited electricians measure available space, check structural load ratings and identify shade patterns to design a system that fits your roof and maximises output.
Can I add a battery later if I start with just panels?
Yes. A quality solar inverter designed for battery storage can be left dormant until you add a battery, usually 12–24 months later. If you buy a basic solar-only inverter instead, you will need to replace it (typically $1,500–$4,200) when you add a battery. Ask Solar Advice about a battery-ready inverter during your design—it costs little more upfront and keeps your upgrade path open. Battery additions usually take 1–2 days to install and integrate with your existing panels.
How much do Small-scale Technology Certificates (STCs) reduce my cost?
STCs are an upfront discount (not a rebate you claim later) managed by the Clean Energy Regulator under the Small-scale Renewable Energy Scheme (SRES). The discount is calculated as: system size (kW) × zone multiplier (1.5–1.6 in most of Australia) × 5-year deeming period × $38 per STC. A 6 kW system in NSW might attract around $3,000–$3,500 upfront; a 10 kW system around $5,000–$5,800. The discount is passed to you by Solar Advice at the point of sale. Confirm current STC prices and zone multipliers with the CER, as both change annually.
What about the Cheaper Home Batteries Program rebate?
From 1 May 2026, the federal Cheaper Home Batteries Program offers subsidies on battery storage (administered by the Department of Climate Change, Energy, Environment and Water). The rates are about $252/kWh for the first 14 kWh, $151/kWh from 14–28 kWh and $38/kWh from 28–50 kWh. A typical 10 kWh battery might attract around $2,500 subsidy; a 15 kWh system around $3,500–$3,800. Amounts and eligibility change, so confirm current thresholds and your state's energy agency requirements before finalising your order. Solar Advice can advise on your eligibility and help with paperwork.
Why does switchboard condition affect my quote?
Your switchboard distributes power safely to appliances and must handle the new solar inverter and any battery charger. An old or full switchboard may need upgrades—adding circuits, replacing the main switch, or even a new board—before installation. A modern switchboard in good condition costs nothing extra; an upgrade can add $500–$2,000+ depending on what's needed. Solar Advice's site assessment includes a switchboard inspection so you see the true final cost before you commit.
Does single-phase or three-phase power change my system size?
Single-phase power (most homes) can usually support up to 10 kW solar without upgrades; three-phase power (some larger homes and businesses) supports much larger systems (often 20+ kW). If you want a system larger than your current phase can handle, you may need an expensive network upgrade from your distribution network operator—costs and wait times vary by postcode. Solar Advice checks your phase capacity during site assessment and explains any upgrade needs clearly so there are no surprises.
What's included in a Solar Advice solar installation?
Every installation includes: site assessment and roof check; system design matched to your consumption and roof; tier-one panels, inverter, racking and safety isolators; installation by SAA-accredited electricians; grid connection paperwork and lodgement with your network operator; monitoring app setup and handover with a walk-through. Post-install support includes warranty registration with panel and inverter makers (typically 10–25 years depending on brand) and access to Solar Advice's phone support for questions. Optional extras include battery storage, EV charger wiring, and solar panel cleaning contracts.