Solar panels in Cardiff

As an estimate, a 6.6kW system comes to about $3,990, a 10kW to about $5,490 and a 13.2kW to about $7,990, with the STC discount for postcode 2285 already taken off. Those are typical figures for a straightforward install, not a fixed price. What those systems are worth to you, though, varies by well over a hundred dollars a year depending purely on which electricity plan you are on — which is the subject of this page and costs nothing to fix.

Cardiff is in STC Zone 3, rating 1.382. In 2026 a 6.6kW system creates 45 certificates, worth roughly $1,710 off the price, and a 10kW system 69 certificates, roughly $2,622. It is a discount applied at the point of sale, not a grant you apply for afterwards. Your retail plan has no bearing on it at all — the certificates come off the system price before a retailer is involved.

There is no single answer, which is why nobody gives you one. There are three shapes to understand. A flat rate charges the same cents per kilowatt-hour whenever you use it. A time-of-use plan splits the day into peak, shoulder and off-peak, with peak usually falling on weekday evenings. A demand tariff adds a separate charge based on your single highest half-hour of usage in the billing period. Which suits you depends entirely on when your household actually uses power, and solar changes that pattern — which is why the plan that was right before you installed often is not afterwards.

Because solar already removes most of your daytime usage, and daytime is the part of a time-of-use plan that is cheap. What remains on your bill is the evening — which is where the peak rate sits. You end up paying the premium rate on the hours you still buy, and collecting the discount on hours you were no longer buying anyway. It is not automatic that time-of-use is a bad deal with solar; it is just that the comparison has to be run on your post-solar usage rather than on the shape your bills had before.

A demand charge bills you on your highest single half-hour of consumption in the period, separately from the kilowatt-hours you used. The catch for a solar household is that this peak almost always happens after sunset — the oven, the aircon and everyone home at once — so a solar system barely touches it. This is one of the few places where a battery does something panels cannot, because discharging through that half-hour directly reduces the charge. If there is a demand component on your bill, it changes the battery arithmetic genuinely rather than rhetorically.

No, and this is the most common mistake made after an install. A headline feed-in rate is the easiest number for a retailer to advertise and frequently rides on top of higher usage rates, so the plan costs you more than it pays. On our NSW modelling figures a kilowatt-hour used in the house is worth 32c and one exported is worth 5c — a gap of 27c — so for most households the usage rate is simply the bigger number in the equation. Compare plans on total annual cost using your own data, not on the one figure in the advertisement.

From your retailer, and you are entitled to it. A smart meter records consumption in intervals, and your retailer can provide that history — which lets you test a plan against what your household genuinely did rather than against an assumption. It is tedious and it is the only way to answer this properly. If you already have solar, ask for at least a full year, because the seasonal shape is the whole point.

The distribution network that owns the poles and wires in your street approves it — not your retailer — and we lodge the application for you. On a flexible export connection, a complying system up to 30kW is automatically approved to export up to 10kW per phase. On a fixed export connection, the approval is 3kW per system. If your home has no reliable internet, exports are limited to a static 1.5kW per system until a connection is available. Your network and your retailer are two different businesses, which is exactly why a tariff question and an export question get different answers from different people.