How the maths works

No black box: this page is every assumption we make, in plain English. If you spot a problem, we want to know.

The core comparison

We split your day into 48 half-hour slots and estimate how much power you use in each. Then we price that same usage two ways: on your current plan's rates, and on a Solar Sharer plan — where usage inside your region's free window costs nothing (up to 24 kWh/day) and everything else is charged at the plan's rates. Both sides include daily supply charges and solar feed-in credits if you have solar. The difference, over a year, is the number on your result screen.

Where your usage shape comes from

Quick mode: a typical Australian household pattern — overnight base load, a morning bump, a midday trough, an evening peak — scaled to your daily kWh. It's a good guide but it is an estimate: treat quick-mode results as roughly ±20%.

Bill mode: if your bill has time-of-use bands (peak / off-peak / shoulder), we use the actual kWh printed for each band instead of the generic shape. Within a band we spread that energy evenly across its hours — we know how much you used between, say, 9am and 4pm, but not exactly when. So a 3-hour free window sitting inside a 7-hour off-peak band captures about three-sevenths of it, not the lot. Controlled-load (separate off-peak circuit) energy is left out, because it's already cheap and stays on its own meter.

Meter mode: if you upload your smart meter data, we use your actual half-hourly usage. That result is close to exact for the period your file covers. The file is read entirely in your browser — it never leaves your computer.

Seasonal adjustment

If your numbers come from a summer or winter bill we scale them down slightly (×0.93 summer, ×0.90 winter) because those quarters overstate the annual average in most homes.

Why we compare whole bills, never rate vs rate

The Solar Sharer plan is designed by the regulator to bring in roughly the same money over a year as a normal time-of-use plan — the free window is paid for by higher rates or supply charges the rest of the day. So a Solar Sharer plan charging more per unit outside the window isn't a red flag; it's the whole design. The only honest way to know if you're better off is to add up a full year of both bills — supply charges, every usage band, feed-in credits — which is exactly what we do.

The 24 kWh free cap

Up to 24 kWh a day in your free window is free. If you use more than that in the window, the extra isn't charged at the peak rate — the rules price it at the network's cheaper off-peak rate. We model that, so a big midday load doesn't get overcharged in our estimate. The fixed daily supply charge is never waived by the free window.

Shifting appliances

Each appliance you tick moves a typical amount of energy (e.g. hot water ≈ 6 kWh, EV top-up ≈ 8 kWh) from the rest of the day into the free window, capped at what you actually use and at the 24 kWh free limit. We also tell you when shifting alone — without switching plans — would save you money.

Hot water on a controlled-load (off-peak) meter

Many homes run electric hot water on a separate, already-cheap off-peak circuit. If that's you, moving it into the free window saves almost nothing (it's already cheap) and some Solar Sharer plans don't even offer that circuit — so when you tell us your hot water is on controlled load, we leave it out of the shifting maths rather than credit a saving that isn't real.

Demand tariffs

Some newer plans add a "demand" charge based on your single highest burst of usage, not just total kWh. We don't model that charge yet. If your bill has one, we say so on your result and treat our estimate as a floor — your real current bill is a bit higher, so switching may help slightly more than we show. We never quietly ignore it.

Solar owners

If you have solar, your midday grid draw is already low, so a free midday window helps less than the headlines suggest — and a different feed-in tariff can outweigh it. That's why we ask for your feed-in tariff and export.

Where plan data comes from

Real plan comparisons use the Australian Energy Regulator's public Consumer Data Right feeds — the same data behind Energy Made Easy — refreshed daily. Each result shows the data date. Our region lookup for South East Queensland approximates the Energex network area by postcode; if we get your area wrong, the quick calculator still works with your own numbers.

What we don't do

We don't store your bill, your meter data, or your answers. We don't take money from retailers. We don't model demand charges or account for pay-on-time discounts and sign-up credits — check those on the retailer's fact sheet before switching.