How many solar panels do I need is the first question most Adelaide homeowners ask, and the answer comes from four numbers: annual electricity use, usable roof area, the inverter export limit on the property, and whether a battery or EV is part of the plan. A typical Adelaide family lands between 6.6 kW and 10 kW, which is roughly 14 to 24 modern panels.
This guide walks through the calculation in the order a licensed installer works through it, so the figures can be checked against a real power bill before any quote arrives.
Step 1: Find Daily Consumption on the Power Bill
Every electricity bill shows total kilowatt-hours consumed and the number of days billed. Dividing one by the other gives average daily consumption, which is the anchor for the entire sizing exercise. If storage is part of the plan, the same figure decides what size solar battery you need.
- 8–12 kWh a day — small household, one or two occupants
- 15–20 kWh a day — typical family of four
- 25–35 kWh a day — larger home with ducted air conditioning or a pool
- 40 kWh or more a day — large home, EV charging, or a home business
Bills covering January and February matter most in Adelaide, because summer air conditioning creates the highest peak the system will ever meet.
Step 2: Convert Consumption Into System Size
South Australia sits in STC Zone 3 with a zone rating of 1.382, and Adelaide roofs commonly return in the order of 4 kWh per installed kilowatt per day averaged across the year. A 6.6 kW system therefore produces roughly 26 kWh on an average day, less in July and considerably more in December.
| Daily Use | Indicative System Size | Approximate Panel Count | Roof Area Needed |
|---|---|---|---|
| 10 kWh | 5 kW | 11–12 panels | ~22 m² |
| 18 kWh | 6.6 kW | 14–16 panels | ~30 m² |
| 25 kWh | 8.8 kW | 19–21 panels | ~40 m² |
| 35 kWh | 10 kW+ | 22–24 panels | ~45 m² |
Panel counts assume current 440 W to 460 W residential modules used on NG Elec’s residential solar installations. Older 370 W panels need noticeably more roof space for the same output, which is why panel count alone is a poor way to compare quotes.
Step 3: Check What the Roof Can Actually Fit
Usable roof area is rarely the same as total roof area. North-facing space carries the most value, west-facing space suits households with a heavy evening load, and anything shaded by a neighbour’s gum tree between 10am and 3pm contributes very little.
Obstructions Cut Into Capacity Fast
Vents, skylights, aerials, solar hot water tanks and roof valleys all remove usable rows. On the narrow returns common to Adelaide’s older bungalows, a nominal 40 m² roof face frequently yields closer to 30 m² of installable area.
Orientation Changes Output, Not Just Position
Panel tilt and direction shift annual yield materially, and the trade-offs are covered in NG Elec’s guide to the best angle for PV panels. A split array across two roof faces often outperforms a single crowded face.
Step 4: Account for the Export Limit
This is the step most online solar panel calculator tools skip. SA Power Networks applies export limits to residential connections, commonly around 5 kW for a single-phase site, which caps how much surplus a home can send to the grid regardless of array size.
A 10 kW array on a 5 kW export limit still makes sense — the extra generation covers daytime load and charges storage — provided the household understands that midday surplus beyond the limit is curtailed rather than paid for. Feed-in tariffs in South Australia have also fallen, with most retailers now paying in the range of a few cents per kilowatt-hour, so self-consumption carries more value than export.
Do I Need More Panels if I Add a Battery or an EV?
Yes, and the increase is larger than most homeowners expect. Storage and vehicle charging both draw from surplus generation, so the array has to produce enough headroom to serve them after the household load is met.
- Adding a battery: allow additional capacity to charge it through winter, not just in summer. A 13.5 kWh battery paired with a 5 kW array will sit part-charged for much of June and July. See solar battery systems for capacity options.
- Adding an EV: a typical commute of 50 km a day consumes roughly 8 to 10 kWh, so plan for around 2 kW to 2.5 kW of extra array if the goal is charging from solar. NG Elec covers the electrical side under EV charger installation.
- Replacing gas hot water: a heat pump shifts hot water onto the array and pairs well with midday surplus — see heat pump installation.
What Else Changes How Many Panels I Need?
Two properties with identical bills can end up with different system sizes, for sound reasons.
- Switchboard capacity may limit inverter size until it is upgraded.
- Single-phase versus three-phase supply changes both inverter options and export allowance.
- Occupancy pattern matters — a household home all day self-consumes far more than one that is empty until 6pm.
- Future plans, including a pool, a granny flat, or a second EV, are cheaper to allow for during the first install than to retrofit later.
- Panel and inverter brand, since NG Elec works with Jinko, AIKO, Trina, Sungrow and Fronius hardware, each with different module dimensions and efficiency.
Longer term, output also depends on keeping the array clean and fault-free, which is where solar panel maintenance and repairs protect the sizing decision.
Get the Number Confirmed for Your Roof
A sizing table gets a household close; a site assessment removes the guesswork. NG Elec’s certified solar electricians and energy specialists review twelve months of consumption data, measure usable roof area, confirm the export limit for the property, and design a system that fits the way the home actually uses power — including room to add storage or EV charging later.
Book a solar assessment with NG Elec on 0425 322 552 for a free quote and a system size backed by your own numbers.
Frequently Asked Questions
How many solar panels do I need for a 6.6 kW system?
A 6.6 kW system uses roughly 14 to 16 panels with current 440 W to 460 W modules, and needs around 30 m² of usable roof space. Older, lower-wattage panels require more panels and more roof area for the same output.
Is a 6.6 kW solar system big enough for an Adelaide family home?
For a household using 15 to 20 kWh a day with no battery or EV, 6.6 kW covers most daytime demand and exports a modest surplus. Families with ducted air conditioning, a pool, or plans for storage generally benefit from 8.8 kW or larger.
Can I install more solar than my export limit allows?
Yes. Export limits restrict what a home sends to the grid, not what the array generates. Oversizing works well where the extra generation is consumed on site or stored, and NG Elec confirms the applicable limit with SA Power Networks before design.
How much roof space is needed per kilowatt of solar?
Allow roughly 4 to 5 m² per installed kilowatt with current panels. Obstructions, roof valleys and required clearances reduce usable area, so the measured figure is usually smaller than the roof looks from the ground.
Does the direction my roof faces change how many panels I need?
It does. North-facing panels produce the highest annual yield, while east and west faces produce less per panel and therefore need more panels for the same annual total. West-facing arrays do suit households with heavy evening consumption.
How much will a solar system cost once the size is settled?
Cost tracks system size, panel and inverter choice, roof complexity and any switchboard work. Contact NG Elec directly for an accurate quote — all pricing is confirmed before any work begins, with no obligation to proceed.
