Solar, batteries, rebates, kilowatts. It's a lot. This page explains everything in plain English so you can decide whether a home battery actually makes sense for you. No technical waffle. No pressure. Just answers.
Think of a kWh like a unit of fuel for your house.
The official definition is "the amount of energy a 1,000-watt appliance uses in an hour", but nobody talks like that. Here's how it actually shows up in your home:
About 0.2 kWh per boil. Five boils = 1 kWh.
About 0.1 kWh. Toaster's pretty efficient actually.
About 1.5 kWh per day. Always on, in the background.
Your last power bill shows how many kWh you used per day on average. Look for "Average daily usage". Most WA households use 18 to 30 kWh per day. About 40-60% of that happens in the evening when solar isn't generating — that's the bit a battery covers.
Solar makes electricity. A battery stores it.
Sit on your roof. When the sun hits them, they generate electricity in real time. If you're not using that electricity right that second, it goes back to the grid (Synergy or Horizon pays you a small amount for it - usually 2-10 cents per kWh).
Sits on a wall in your garage or outside. When your solar is making more than you're using, the extra goes into the battery instead of to the grid. Then at night, you use it from the battery instead of buying expensive grid power (28-32 cents per kWh).
It's a discount paid by the government, applied to your install price.
You don't get a cheque in the mail. The installer applies the discount directly to your invoice. So if your battery costs $13,000 and the rebates add up to $9,000, you pay $4,000 to the installer and they claim the rest from the government.
Called the Residential Battery Rebate Scheme. Funded by the WA Government from a $337 million pool. Capped at 100,000 households across WA. First come, first served.
How much: Up to $5,000 if you're on Synergy (Perth metro + south west). Up to $7,500 if you're on Horizon Power (regional WA). The larger Horizon rebate is to reduce diesel generation out in the regions.
Called the Cheaper Home Batteries Program. Funded by the Albanese federal government. Available everywhere in Australia.
How much: About $330 per kWh of battery capacity in 2026. So a 13.5 kWh battery gets about $4,450 from the federal side. The amount steps down each year (see Question 8 below for why this matters now).
You stack both. State + federal. Your installer applies both discounts at the same time. There's no separate paperwork on your end - they handle it.
In almost every case, yes. Here's why.
A battery without solar is like a fuel tank with no way to fill it. You'd still have to buy electricity from the grid to charge it. The economics don't work.
If you already have solar, perfect - you can add a battery and the rebates apply. If you don't have solar yet, install both at the same time with the same installer. There's a separate federal rebate for solar panels (called STCs - Small-scale Technology Certificates) that's been around for years and is still active.
Probably smaller than the installer will try to sell you.
Look at your power bill. Find your average daily usage in kWh.
Once you go above 10 kWh, the state rebate is capped (at $5,000 Synergy / $7,500 Horizon). You don't get any more state money for a bigger battery. The federal rebate keeps adding $330 per kWh, but it's not enough to make a 20 kWh worth it for an average household.
Pushy installers will quote you a 20 kWh system "for future-proofing". 9 out of 10 households are better off with 10-13.5 kWh.
You don't choose. Your postcode chooses for you.
Perth metro + south west. About 1.1 million customers. Connected to the South West Interconnected System (SWIS) — a single big electricity grid.
State rebate cap: $5,000.
Regional WA: Pilbara, Kimberley, Mid West, Goldfields, parts of the south coast. About 100,000 customers. Lots of small isolated grids, often diesel-backed.
State rebate cap: $7,500. Bigger because batteries reduce diesel use.
Four-step thing. Takes you about 60 seconds, we do everything after.
Two real reasons. No fake countdown timer.
The Cheaper Home Batteries Program drops in value each year on purpose - it's designed to phase out by 2030 once batteries are normal-priced without subsidy.
2026 rate: ~$330/kWh
2027 rate: ~$260/kWh
2028 rate: ~$200/kWh
2029 rate: ~$130/kWh
2030 rate: near $0.
What this means for you: for a 13.5 kWh battery, installing in 2026 instead of 2027 saves you about $945. Waiting until 2028 costs you about $1,755 versus this year.
The $337M state pot covers about 100,000 households across WA. Once that's hit, the scheme ends - regardless of which year it is. There's no obligation for the government to top it up.
At current uptake rates (which are accelerating fast), the cap is expected to be hit somewhere between mid-2027 and end-2028. After that: federal rebate only, much smaller.
Yes. Reply to any email from wattsmyrebate@outlook.com or send a fresh one - Christian (that's me, the person who built this site) will get back to you within a few hours.
You don't have to submit a quote request first. If you've got questions like "I live in a unit, can I even get this?" or "my roof faces south, is it worth it?" - just ask. No sales pitch.
If you want a number first, run the calculator. If you want 3 quotes from real installers, that takes 60 seconds.