Mercury review

Mercury is New Zealand's third-largest electricity retailer and a major generator, listed on the NZX and majority Crown-owned. It absorbed Trustpower's retail customer book, which is why Trustpower no longer sells power under its own name. If you are looking for Trustpower, Mercury is who you would now be dealing with.

What Mercury actually offers

Mercury's residential electricity comes in two pricing shapes: flat rates, where a unit of power costs the same whenever you use it, and flex rates, where it costs less off-peak and more at peak. That choice is the main decision to make, and it is a genuine one: flex rewards households that can move heavy use, flat protects households that cannot.

On top of that sits a fixed-price plan structure. Mercury runs terms such as 2 years, and its larger sign-up credits are generally attached to them. We saw a $300 credit advertised when we checked on 27 July 2026. Mercury runs several offers concurrently with different credits and different terms, so treat that as one snapshot of a moving picture.

Piped natural gas and bottled LPG are both available, as are broadband and mobile.

The renewable claim, and why it is worth taking seriously

Mercury states that its generation assets produce electricity from 100% renewable sources — hydro, geothermal and wind.

That is a claim about generation rather than a marketing label bought in, which makes it one of the stronger environmental positions on offer here. It is worth understanding what it does and does not mean: electricity from the national grid is physically the same regardless of who you buy it from. What differs is whose generation your money supports. If that matters to you, Mercury and Meridian are the two companies we compare that make this claim about their own generation.

Who it suits

Mercury suits households that want price certainty and are willing to commit for it. A multi-year fixed-price plan with a sizeable joining credit is a real offer, provided you intend to stay.

It suits dual-fuel homes, since piped gas and LPG are both available.

And it suits people for whom renewable generation is a deciding factor rather than a nice-to-have.

What to watch

The credit and the commitment travel together. Mercury's larger sign-up credits are attached to fixed terms. That is not a trick. It is how a company recovers an upfront credit, but it does mean the headline number and the lock-in are the same decision. Work out whether you are likely to move house or switch again inside the term before taking one.

Leaving early can cost. Check what a break fee looks like on the specific offer before you sign, not after.

Several offers run at once. At the time of writing Mercury had multiple concurrent credits attached to different terms. Compare the one you are actually being offered.

How Mercury compares

Against Contact and Genesis, Mercury covers similar ground — big generator, gas, telco bundles — and differentiates on the renewable generation claim and the fixed-price structure.

Against Meridian, the two are closest on environmental positioning; Mercury adds gas, which Meridian does not sell.

As with every company here, we do not yet show what Mercury's power costs, because rates depend on your network region, user type and meter. Compare on what is verifiable, and confirm the credit, the term and the break cost with Mercury before committing.