The STC Solar Discount Explained (And Why It Shrinks)

When you get a rooftop solar quote in Australia, a big chunk of the discount is already baked in before you talk numbers. That discount comes from the federal Small-scale Renewable Energy Scheme (STCs) — Small-scale Technology Certificates. It's national, it applies whether you're in Perth or Penrith, and most people never see how it actually works. Here's the plain-English version, including the part the installer won't dwell on: the discount is designed to get smaller every year.

What an STC actually is

An STC is a tradeable certificate the government creates for each unit of clean electricity your system is expected to generate over its remaining scheme life. Install a bigger system, or install it in a sunnier zone, and it's worth more certificates. Those certificates have a dollar value, and the standard industry practice is for the installer to claim them on your behalf and subtract their value from your price up front.

That's the key thing to understand: you almost never receive STCs as cash. They're already reflected in the "after STC" price on your quote. The Clean Energy Regulator administers the scheme; the certificate price moves in a market, so the exact discount varies a little from quote to quote.

What it means for a real system price

To give you a sense of scale, here are indicative after-STC installed price ranges we use as national benchmarks:

System size	Indicative installed price (after STC)
6.6 kW	$4,000 – $6,500
10 kW	$6,000 – $10,000
13.2 kW	$7,500 – $13,000

These are ballpark ranges, not quotes — your roof, switchboard, phase type and location all move the number. As a rough planning figure, a well-sited system yields around 1,400 kWh per kW per year in our national model, which is what determines whether the whole thing actually pays.

One practical constraint worth flagging early: many single-phase homes are limited to a 5 kW export limit. That doesn't stop you installing more panels, but it does cap how much you can send to the grid at once — which matters because feed-in credit is where a lot of the "payback" story lives.

Why the discount shrinks over time

Here's the mechanism most quotes gloss over. The number of certificates a system earns is tied to how many years remain in the scheme. The scheme has a fixed end date, so every year the calculation window gets shorter — which means the same-sized system earns fewer STCs than it did the year before.

In plain terms: the STC discount is on a slow, deliberate glide path down to zero. This isn't a glitch or a "limited-time offer" pressure tactic — it's how the scheme was built. The effect is gradual, not a cliff, so there's no need to panic-buy. But it does mean the sticker price of solar tends to creep up over time as this support tapers off, all else being equal.

Here's the catch — the discount doesn't decide whether solar pays

A smaller upfront price is nice, but it's not the whole equation, and this is where independence matters. The STC discount lowers what you pay today. Whether the system ever pays for itself depends on what your exported power is worth tomorrow — and feed-in tariffs are falling.

Feed-in rates in our national model sit in a wide 3–10 cents per kWh band, mostly set by retailers and trending down (a few states set a regulated minimum — confirm the current rate where you are). If you're out of the house all day and exporting most of your generation at a few cents a kilowatt-hour, a bigger, cheaper-per-watt system can still be a slow earner. Solar pays best when you use what you make.

So the honest framing is:

• The STC discount is real and worth having — it's the reason solar is affordable at all.
• It shrinks slightly each year, so waiting a decade will cost you a little more.
• But it is not a reason to rush, and it says nothing about whether solar suits your usage pattern.

For some households — low daytime use, poor roof orientation, a low feed-in tariff — the numbers simply don't stack up yet, even with the STC discount fully applied. That's a legitimate answer, and it's one you'll rarely hear from someone selling panels.

A quick note for businesses

If you run a warehouse, farm, factory or school, there's a significant change worth watching. From 1 October 2026 (subject to final regulations — confirm commencement), the SRES threshold is set to rise from 100 kW to 1 MW. That means commercial systems in the "missing middle" (100 kW–1 MW) would create STCs upfront at install rather than relying on large-scale certificates — an estimated ~20% cut to upfront cost. Systems under 100 kW already earn STCs today; over 1 MW stays on the large-scale path.

We don't sell or install a single panel, and we earn nothing from your STCs. Our only job is to tell you whether solar actually pays for your home or business — including when the honest answer is "not yet."

Figures in this guide are current at the date of publication and indicative only — rebate and certificate values change over time (federal battery certificates step down each January and July), and state schemes are amended often. Confirm the current numbers for your situation before you commit. This is general information, not personal financial advice.