Rouse Hill and Kellyville are not your average Sydney suburbs when it comes to power bills. The homes out here are large, mostly newer, and packed with the things that drive electricity use: ducted air conditioning, pools, big kitchens, home offices, and increasingly an EV in the garage. Summers in the Hills District get hot, and the air con runs hard through the evening, which is exactly when grid power is most expensive.
That combination makes this one of the best parts of Sydney for solar and battery. Get the setup right and you can run most of that evening load off your own stored sunshine instead of buying it back at peak rates. Here is what a well matched system looks like for a typical home in these suburbs.
Why these suburbs suit solar so well
A few things about Rouse Hill and Kellyville homes push the numbers in favour of a solid system.
The rooftops are generous. Newer detached homes here tend to have large, unshaded roof areas, often with sections facing several directions, which gives plenty of room for a bigger array. Many properties are also on three phase power, which is common in newer estates and matters a lot once you add a battery, more on that below.
The energy use is high and evening heavy. Ducted air conditioning is close to standard, pools are common, and family households use a lot of power after school and work. Because most of that consumption lands in the evening and overnight, a battery has plenty to do, which is what makes storage pay off faster here than in a small, low use home.
The panels: aim bigger than you think
For homes this size, a small array does not cut it. A 6.6 kW system, which used to be the default, will struggle to cover heavy summer air con and still have surplus to charge a battery. For most Rouse Hill and Kellyville homes, a system in the 10 kW range or larger is the better starting point, and many roofs here have the space for it. Our breakdown of a 6.6kW vs 10kW system for Sydney homes walks through the difference.
A bigger array does two jobs. It runs more of your daytime load directly, and it generates enough surplus to fill your battery even on a cloudy day, so you are not left short in the evening. If your roof faces multiple directions, spreading panels across east, north, and west actually helps, because it stretches your generation across more of the day rather than piling it all into the middle.
The battery: size it, and mind your phases
A battery is what turns a good solar system into a low bill. Without one, your surplus solar gets exported for a feed in tariff that has fallen a long way in recent years, then you buy it back at night at peak prices. Storing it instead is where the savings now sit.
For a family home in these suburbs running air con most summer evenings, a battery around 13 to 16 kWh is usually the right zone. That covers a normal evening and overnight run with headroom, and it lines up with the 2026 rebate, which we will come to. Not sure on capacity? Our guide on what size solar battery you need runs the numbers, and you can compare models on the home battery range.
Here is the part specific to this area. Because so many homes here are three phase, the type of battery matters. Some three phase batteries split their output evenly across all three phases, which is a problem if your ducted air con sits on one phase during a blackout, since that phase only receives a third of the battery’s power. Batteries that support unbalanced three phase output can send the full discharge to the phase that actually needs it. If backing up your air conditioning through an outage matters to you, this is worth raising with your installer before you choose a battery. Our guide on integrating air conditioning with solar has more on this.
The 2026 rebate, and why timing counts
The federal Cheaper Home Batteries Program changed on 1 May 2026. It moved from a flat discount to a tiered one, and it now steps down every six months instead of once a year.
The full rebate rate now applies to the first 14 kWh of usable battery capacity, then tapers sharply above that. As of mid 2026 it is worth roughly $250 per usable kWh across that first 14 kWh, with the next reduction locked in for 1 January 2027. This is why a battery sized around 13 to 16 kWh is the value pick for most local homes: it captures the strongest rebate before the taper, while still covering a big family’s evening load. See our federal battery rebate guide for the full detail.
To qualify, your system needs to be VPP capable, use CEC approved products, and be installed by a Solar Accreditation Australia accredited installer. NSW homeowners can also look at any state incentive they are eligible for on top of the federal rebate. Because the rebate steps down on a set schedule, installing sooner rather than later locks in a stronger rate, so there is a real cost to waiting.
Putting it together for a typical Hills home
For a standard four bedroom home in Rouse Hill or Kellyville with ducted air con and a pool, a sensible starting setup looks like this:
- Solar: around 10 kW or more, spread across the available roof faces
- Battery: around 13 to 16 kWh, with unbalanced output if you are on three phase and want air con backup
- Rebate: federal battery rebate on the first 14 kWh, ideally installed before the next step down
- EV ready: if a car is on the horizon, factor that into both the array and battery size now, so you are not resizing later
Every home is different, and the exact numbers should come from your actual usage data and roof, not a template. Greenlight Solar can assess your roof, pull your consumption profile, and design a system matched to your phase setup and how your household really runs. We already look after homes across the Hills, including Kellyville, Castle Hill, Baulkham Hills and Box Hill. Book a free assessment to get started.
Frequently asked questions
What size solar system is best for a Rouse Hill or Kellyville home?
For most large homes in these suburbs, a system around 10 kW or larger is the right starting point. The homes here are big, energy use is high, and the roofs usually have the space. A 6.6 kW array often struggles to cover heavy summer air con and charge a battery as well.
Do I need three phase power for solar and battery?
Not necessarily, but many newer homes in these estates already have it. If you are on three phase and want to back up appliances like ducted air con during a blackout, choose a battery that supports unbalanced output so it can send full power to the phase under load.
How big should my battery be?
For a family home running air con most evenings, around 13 to 16 kWh usually fits. That covers a normal night with headroom and lines up with the federal rebate, which pays its full rate on the first 14 kWh before tapering.
Is solar still worth it now that feed in tariffs have dropped?
Yes, and arguably more so. Because export tariffs have fallen, the value has shifted from selling surplus power to storing and using it yourself. A battery lets you run your evening load off stored solar instead of buying peak grid power, which is where the savings now are.
Can I claim the battery rebate in NSW?
Yes. The federal Cheaper Home Batteries Program applies nationwide, including NSW, as long as your system is VPP capable, uses CEC approved products, and is installed by an accredited installer. You may also be able to stack any NSW state incentive you qualify for.
Should I install before the next rebate change?
There is a real benefit to acting sooner. The rebate steps down every six months on a set schedule, with the next reduction on 1 January 2027, so an earlier install locks in a stronger rate per kilowatt hour.
