Most people come to us asking one thing: how big a system do I actually need, and what's it going to cost? For a typical Sydney or Newcastle home you're looking at $5,000 to $9,000 for solar after the federal STC rebate, and roughly another $8,000 to $14,000 if you add a battery, before the NSW incentive comes off.

Those are broad ranges on purpose. The right system depends on how much power you use, when you use it, and what you want it to do when the grid goes down. Here's how to compare the three things that matter without drowning in spec sheets.

Panel size: match it to your bill, not the roof

Panel size is measured in kilowatts (kW). A 6.6kW system is the most common size we install, mostly because it pairs neatly with a standard 5kW inverter and sits right under the limit before some networks want extra approvals.

To size it properly, grab your electricity bill and look at your daily usage in kWh. A household using around 20kWh a day suits a 6.6kW system; heavier users with ducted air-con or a pool pump often justify 10kW or more. Don't oversize just because there's roof space going spare.

With feed-in tariffs now sitting at a measly 4–7c/kWh, exporting excess power barely pays. The real value is in self-consumption, so the goal is running your daytime appliances off the sun rather than selling it back for pocket change.

Battery capacity: how many kWh do you really use after dark?

Battery capacity is also in kWh, but that number can mislead you. What counts is usable capacity, not the headline figure — a 13.5kWh battery might only give you around 13kWh you can actually draw before it hits its cut-off.

Work out your evening and overnight usage. If you use 12kWh between sunset and sunrise, a 10kWh battery covers most nights but not all. Going bigger buys you cloudy-day buffer, but every extra kWh adds cost, so there's a point of diminishing returns.

The NSW battery incentive introduced in late 2024 knocks a meaningful chunk off the upfront price, scaled to capacity, and there's an extra rebate if you connect to a Virtual Power Plant. That's shifted the maths for a lot of homes in Dee Why and Charlestown that couldn't previously make a battery stack up.

Backup features: not all batteries keep the lights on

This is where people get caught out. Plenty of homeowners assume any battery means power during a blackout — it doesn't. Standard grid-connected batteries shut down in an outage for safety, same as your solar does.

For genuine backup you need a battery with a backup gateway or a dedicated backup circuit. Some systems back up the whole house; most back up an essential circuits sub-board — fridge, some lights, internet, a power point or two. Whole-home backup costs more and often needs a bigger battery to handle the surge when something like an air-con compressor kicks in.

If you're on the Northern Beaches, where storms take out power more often than most Sydney suburbs, backup is worth paying for. In Frenchs Forest we've wired essential-circuit backup for households that just want the fridge and a few lights riding through an outage without the expense of full-house backup.

What we check on the quote visit

A quote done off satellite imagery and a phone call misses the things that blow out the price. The single most common mistake we fix is a switchboard that's too old or too full to take a battery — no spare ways, no main switch of the right rating, sometimes ceramic fuses that legally have to go before we touch anything.

We also check your meter and which network you're on. Ausgrid and Endeavour have different connection processes and approval limits, and if you've still got an old accumulation meter, it needs swapping to a smart meter before solar exports can be credited. That's a separate job with its own lead time, and we'd rather flag it upfront than surprise you later.

On the roof we look at orientation, shading from gum trees or a neighbour's second storey, and whether the tiles or Colorbond can be penetrated cleanly. A north-facing array is ideal, but in a place like Mona Vale a split east-west layout often suits homes that use power morning and evening more than midday.

Get numbers based on your actual home

The right system is the one sized to your bill, your evening usage and how much you care about blackout backup — not the biggest one someone can sell you. Once we've seen your switchboard, meter and roof, we can give you real figures with the STC rebate and NSW battery incentive already applied.

Book a free on-site assessment with us and we'll walk you through options built around your place, across Sydney, the Northern Beaches and Newcastle.