Solar battery installation and retrofit
The part most battery quotes skip: which circuits stay alive when the grid goes down, and how that's actually wired.
Blackout protection is not automatic
This is the single most misunderstood thing about home batteries, and it causes real disappointment.
A battery installed without backup circuits does nothing in a blackout. It shuts down along with everything else, because grid-connected inverters are required to disconnect when the grid goes down — otherwise they'd energise lines that linesmen may be working on. Owners discover this during their first outage, standing next to a fully charged battery in a dark house.
Getting blackout protection means the battery system has a backup capability, and — the part that's actual electrical work — the circuits you want to keep alive are wired onto the protected side of the installation. That's a switchboard job, and it's the bit that gets left out of a package price.
On acreage it's not a nicety. If you're on a tank or bore pump, no power means no water, and Hills rural feeders stay down considerably longer than suburban ones.
Choosing your backup circuits
A home battery can't run everything. Backup capacity is limited, and the point is to keep essential things going for a useful length of time rather than everything for twenty minutes.
What we normally put on the protected side:
- Fridge and freezer — the thing that actually costs money in a long outage
- Water pump, on tank or bore supply
- Lighting in main living areas
- Internet and comms, increasingly the difference between working and not
- A few general outlets for phones, laptops and medical equipment
- Septic pump where fitted
What we normally leave off: air conditioning, electric hot water, oven, pool pump. Any one of them will empty a domestic battery in short order.
Deciding this properly at design stage is most of the value. It's much harder to rearrange afterwards.
Retrofitting to existing solar
Most Hills battery jobs are retrofits onto solar installed between 2012 and 2020. Two paths:
AC-coupled — the battery has its own inverter and sits alongside your existing solar inverter, which stays as it is. Simpler, doesn't disturb a working system, and sensible if your existing inverter is relatively new.
DC-coupled / hybrid — the existing inverter is replaced with a hybrid that handles both solar and battery. Slightly more efficient, and it makes obvious sense if your inverter is already 8+ years old and near end of life anyway. If it's failing, replacing it with a hybrid rather than a like-for-like is often the better call — see solar repairs.
Either way, the switchboard usually needs work, and that's worth knowing before you compare package prices that don't include it.
What the electrical side costs
Sydney, 2026. Battery hardware and installation is usually a package from your supplier — these are the electrical items that sit around it.
| The job | Price |
|---|---|
| Backup circuit wiring at the switchboardMoving nominated circuits onto the protected side. The item most often missing from a package price | $800 – $2,200 |
| Switchboard upgrade to accept a batteryWhere the board is full or lacks RCD protection | $1,500 – $3,500 |
| Hybrid inverter changeover, electrical workWhere an ageing inverter is being replaced as part of the job | $600 – $1,400 |
| Surge protection for battery and inverterStrongly worth it on rural feeders | $400 – $900 |
| Pre-battery assessmentWhat your board and existing solar can actually accommodate | $180 – $350 |
These are indicative market ranges for Sydney in 2026, not a quote. What you pay depends on your switchboard, access and what we find. We confirm a fixed price before starting, and it doesn't move.
Solar battery questions
Will a battery power my house in a blackout?
Only if it's installed with backup circuits, and only the circuits you nominate. Many batteries are installed with no blackout capability at all — the owner finds out during the first outage. If backup matters, say so before signing anything, because it changes the wiring and the price.
Which circuits should I back up?
Fridge and freezer, water pump if you're on tank or bore, lighting in main living areas, internet, and a few general outlets. Leave off air conditioning, electric hot water, the oven and the pool pump — any of them will flatten a domestic battery quickly.
Can I add a battery to my existing solar?
Yes. Either AC-coupled, with the battery bringing its own inverter alongside your existing one, or by replacing your inverter with a hybrid. If your inverter is already 8+ years old, the hybrid path usually makes more sense since it's near end of life anyway.
What size battery do I need?
Size to your evening and overnight consumption rather than to your total daily use — the solar covers the day. Since the May 2026 federal rebate tiering, the first 14kWh attracts the full rate, which makes at or just under that the efficient point for most households.
What rebates are available?
The federal Cheaper Home Batteries discount of roughly $300 per kWh, plus a NSW payment of up to about $1,500 for joining a virtual power plant. NSW's own standalone battery rebate has been paused since July 2025. Our rebate guide covers the detail.
Do you sell batteries?
No — we're electricians, not a solar retailer. We do the electrical work around a battery, which is the part that determines whether it actually does what you wanted in an outage. We're happy to work alongside whichever supplier you choose.
What customers say
Jason solved a really complex problem for our house with excellent professionalism and workmanship. Highly recommend, would def work with him again. On time delivery and within budget.
Jason onsite quickly and completed the work on the spot, giving us a good price and was very polite. Would highly recommend.
Fantastic service! Friendly, efficient and well priced. Highly recommend. Thank you for swiftly fixing our switches.
These are Google reviews for our team at Cync Electrical & Automation — the licensed contractor behind Hills Electrician. 5.0 from 20 reviews. — see the profile
Getting a battery quote?
Ask whoever's quoting whether backup circuits are included. If they hesitate, call 0422 253 379.
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