New Home Solar Installations
It is practically impossible to give you firm quotes if your new home is 6 months away or more. This is because the amount of “solar rebate” received can change over time and can only be locked in once the panels are on the roof.
Here are ballpark prices for your budget:
Solar only
- 6.6kW: $5,500 – $9,000
- 10kW: $8,000 – $13,000
Solar + batteries
- 6.6kW + 13kWh battery: $19,000 – $26,000
- 10kW + 13kWh battery: $21,000 – $30,000
The lower end is for budget brands – the higher end for premium brands.
Prices include the “solar rebate” that’s available throughout Australia, but some locations have additional incentives. In Victoria, most solar installations can receive a $1,400 rebate and NT and NSW have battery rebates. The NT battery rebate will lower the cost of a 13kWh battery by $5,200 while the NSW battery rebate will take roughly $2,000 off a 13kWh battery.
When it comes to sizing a solar system for a new home – my advice is to put on as much solar as you can reasonably fit and afford.
The exact amount you can put on depends on the rules set by your local electricity network and whether your home is single-phase or three-phase (three-phase houses can put on a LOT of panels, assuming they’ll fit.) For most homes I recommend at least 10kW.
You can see the sizing rules for your state here.
A typical modern solar panel is around 1.76m long and 1.13m wide, with a 440 watt (W) capacity. This gives it a surface area of 2m² and a capacity of 220W per m². But this doesn’t mean a 10m² section of roof can can hold 2,200W of solar panels. How many fit will depend on the size and shape of the roof and panels. If a roof section is large and conveniently shaped, perhaps over 90% of it can be covered with panels. But if a roof section is small and awkwardly shaped, it’s possible less than half the space can be used for panels.
While north facing offers ideal yield at midday, it’s often better to have East and West arrays to capture more solar energy early and late in the day (before 10am & after 3pm) as the cost of grid electricity can be higher for those on time-of-use tariffs. It also increases the total amount of solar energy consumed by homes, which further lowers bills.
When you are talking to your architect or home builder these are the things to discuss to ensure your solar system can be installed easily and works at max capacity:
- Can every roof face accommodate solar?
These days solar is cheap and the perfect roof is one that’s simply covered in panels regardless of which direction the roof section is facing.
Incredibly – many new homes come as standard with roofs that cannot structurally support a decent sized solar system.
Ensure you get written assurances from your builder that every roof face can be filled with solar panels. If you have to ‘upgrade’ to do this it should only be a few hundred dollars. More info here.
- Is there room next to the switchboard for the solar inverter and/or battery?
Will this be shaded from full sun? An alternative is to place the inverter and/or battery in the garage – in which case run the wires before the walls are gyprocked.
- Ask for a bigger switchboard.
Your builder will tell you you’re nuts, but if you pay a few hundred now it will save you thousands on switchboard upgrades when you run out of space in the future. I speak from bitter experience!
- Ask the sparky to run an ethernet cable from wherever your modem/router will be to the inverter location.
A hard wired cable from your inverter to your internet router provides a much more reliable connection than using wi-fi. The same goes for connecting a battery or solar monitoring to the internet.
- Also ask the sparky to run a shielded twisted pair cable from the inverter position to the main switchboard.
This link is essential for flexible exports being rolled out across the country.
- Where will the drain vent pipe exit the roof?
Will this shade the solar? Can it go on the south facing roof – out of the way? If this is not possible – can you specify an ‘Air Admittance Valve’ instead of a roof penetration?
- Where will your TV aerial go?
Can it also go on the south roof out of the way of any solar? Do you even need an aerial these days?
- If the sparky is laying new cables to the street, can he make them thicker than normal to avoid voltage drop issues?
Tell the sparky you want a voltage drop less than 1% (about 2V) when pushing 10kW into the grid.
- If you have a choice between 3-phase and single-phase – be aware that you can install 3 times as much solar with a 3-phase connection.
Might be handy if you get an electric car or batteries in the future.
Speaking of electric cars – I’d strongly recommend having your installer pre-wire your garage/driveway in anticipation of adding a charger in the future.
Ask them for a single or three phase cable rated at 32A per phase, continuous. Ask them to terminate it at a 32A socket and include a drawstring for a data cable.
Pre-wiring
I strongly advise pre-installing the wiring for your solar system during the build. The installers can really easily and neatly pre-wire the house for solar before the walls are gyp-rocked. If the installers save time and money then the savings can be passed to you.
If your builder insists on using their own sparky to do the pre-wiring, then ideally get your installer to specify what they want. Otherwise ask for:
“A 25mm HD SOLAR conduit from where you want the inverter to the roof. Run the AC from the MSB to where you want the inverter: 10mm TPS for single-phase, and 4mm orange circ for three phase. Also run a shielded twisted pair cable from the inverter to the MSB for a smart meter.”
Metering
Get a solar-ready electricity meter installed from the outset. Then you won’t have to replace it. This can save you hundreds of dollars. Ensure the builder’s sparky knows to do this. By default you may get a non-solar meter!
Scaffolding
If you’re building a multi-storey house put your solar panels on the roof before the scaffolding comes down. You don’t want to pay for scaffolding twice.
And finally – Get A Firm Quote (or quotes) 3-4 months before handover – this timing usually ties in nicely with getting the walls pre-wired before the gyprocking happens.
About Finn Peacock
I’m a Chartered Electrical Engineer, solar and energy efficiency nut, electric car and e-bike owner, dad, and founder of SolarQuotes.com.au. My last “real job” was working for the CSIRO in their renewable energy division. Since 2009 more than 835,439 Australians have used my site to get quotes for high quality PV systems from pre-vetted solar installers.