The Dynamic Tariff & Buy-Back Engine

The Dynamic Tariff & Buy-Back Engine is a free, live-updated comparison tool that shows you what every major New Zealand electricity retailer is currently paying for the solar power you export to the grid. You plug in your region, your estimated system size, and your typical daily generation. We show you the current buy-back rate from Octopus Energy NZ, Ecotricity, Meridian, Contact, Genesis, Mercury, and Frank Energy, then calculate your potential annual export earnings. No login, no email gate, no spam. This is our single source of truth for live retailer buy-back rates across the site, so every figure you read in our tariff articles points back here. Because rates change without much fanfare, and you deserve the current number, not last year's number dressed up as fresh.

What This Tool Does

The Engine does two jobs at once. First, it lets you compare buy-back rates side by side across the main NZ retailers offering solar export plans. Second, it calculates how much you could earn annually from exporting surplus solar based on your own system size and generation profile.

You don't need to be on solar yet to use it. If you're researching whether to install, the Engine helps you forecast a realistic export income on top of your self-consumption savings. If you're already generating, it tells you whether your current retailer is still the best fit, or whether it's time for a polite phone call to switch.

What You'll Need to Get the Most Out of It

You can use the Engine with rough estimates, but the more accurate your inputs, the more accurate your output. Here's what helps:

• Your region or postcode, so we can apply the right lines-company context (Vector, Orion, Wellington Electricity, Powerco, Aurora, and so on)
• Your system size in kilowatts (kW), or if you're still planning, the size you're considering (3 kW, 5 kW, 6.6 kW, 10 kW are common sizes in NZ)
• Your daily generation estimate in kWh, or your annual figure if you have it. If you're planning, our Solar System Cost & ROI Calculator will give you a realistic generation estimate for your region.
• An estimate of how much you self-consume vs. export. Most NZ homes export 40-70% of what they generate, depending on whether anyone's home during the day.
• Your current retailer (optional), so you can see the comparison from where you sit today

If you don't have all of these, no stress. The Engine has sensible default assumptions for each region, and you can refine as you go.

How It Works (In Plain English)

Behind the scenes, the Engine pulls together three things: the current advertised buy-back rate from each retailer's published solar plan, any tier or time-of-use rules (some retailers pay a flat rate, others pay more during peak windows), and your generation profile.

It then runs a simple calculation: estimated export kWh per year multiplied by the relevant cents-per-kWh rate, adjusted for any time-of-use weighting. The output is an estimated annual export income figure for each retailer, ranked highest to lowest.

The clever bit is the dynamic tariff handling. Retailers like Octopus Energy NZ offer plans where the rate varies by time of day. If your solar mostly exports at midday (which it will), a midday-peak buy-back rate behaves very differently from a flat rate. The Engine models this rather than just averaging it, which is where most back-of-envelope comparisons go wrong.

We update the underlying rates regularly by checking each retailer's public plan pages. When a retailer changes their buy-back rate, our tool reflects the change, and so does every article on this site that references current rates.

What We Do With Your Information

Nothing. Truly.

The Engine runs locally in your browser. The inputs you provide (region, system size, generation) are not sent to us, not stored in a database, not added to a marketing list, and not sold to installers or retailers. There is no email gate, no signup, no "give us your phone number to see the results."

If, after using the tool, you decide you'd like quotes from vetted installers, you can choose to head to our free quote-matching service. That's an entirely separate action you control. The two systems don't talk to each other.

This is how we think a trust proxy should behave. You shouldn't have to barter your contact details to see a public buy-back rate.

Why You Can Trust This Tool

Three reasons.

One: the rates are sourced from public retailer plan pages. We don't make them up, and we don't take them from a partner who has an incentive to inflate them. If Octopus, Ecotricity, Meridian, Contact, Genesis, Mercury, or Frank publishes a solar plan with a stated buy-back rate, that's the number we use. We link out to the source plan page so you can verify.

Two: we update on a defined cadence. Retailers occasionally change their solar offers without much warning. We monitor the public pages and update the Engine when we notice changes. If you spot a rate that looks out of date, please tell us and we'll have a yarn with the retailer and update within 48 hours.

Three: the methodology is documented. The maths is published in plain text alongside the tool. No black box. If you want to know exactly how an annual figure was calculated, every assumption is on the page. For terminology like "buy-back rate", "net metering", "export rate", or "time-of-use", see our NZ Solar Jargon Buster glossary.

NZ Solar Centre is independent and reader-supported. We earn revenue when readers choose to be matched with vetted installers through our quote service. We do not earn revenue from electricity retailers, which means the rankings in the Engine are not influenced by who pays us. The retailer at the top is the retailer paying the best rate for your situation. Full stop.

A Quick Note on Realistic Expectations

The Engine shows you export earnings, which is one part of the solar financial picture, not the whole picture. The bigger win for most NZ households is self-consumption: the power you generate and use yourself, which offsets your retail buy rate (typically 30-40c per kWh) rather than your export buy-back rate (typically 7-17c per kWh).

That gap matters. A unit consumed at home is worth roughly two to four times what the same unit is worth exported. So while it's smart to choose a retailer with a strong buy-back rate, it's even smarter to size your system around your daytime usage. For the full ROI picture, including both self-consumption savings and export income, run your numbers through our Cost & ROI Calculator after you've finished here.

And if you're planning your install with a green loan from Westpac, ANZ, BNZ, or Kiwibank, check eligibility with The Green Finance Qualifier before you sign anything.

Frequently Asked Questions

How often are the buy-back rates updated?

We monitor each retailer's public solar plan page regularly and update the Engine whenever we detect a change. In practice, most NZ retailers adjust their rates once or twice a year, sometimes alongside broader plan changes. If you see a rate you suspect is stale, drop us a line and we'll verify within 48 hours.

Is the Engine accurate enough to choose a retailer based on it?

For comparing headline buy-back rates, yes. For a binding decision, always check the retailer's plan terms directly (we link out to each one), because some plans have conditions like minimum daily charges, tiered rates, or contract terms that can affect the real-world outcome. The Engine gives you the shortlist; the retailer's plan page gives you the contract detail.

Why do buy-back rates vary so much between retailers?

Different retailers value solar export differently based on their generation mix, wholesale exposure, and customer strategy. A retailer like Octopus, which leans into smart tariffs, may pay more for power that arrives during certain hours. A traditional retailer may pay a flat lower rate. Neither is "wrong"; they just suit different households.

Do I need to be a customer of a retailer to see their buy-back rate?

No. All rates shown are publicly advertised. The Engine simply pulls these into one place so you don't have to open seven browser tabs.

Does the Engine work for commercial solar?

The Engine is built for residential systems (typically 3 kW to 10 kW). Commercial solar export arrangements are usually negotiated case by case and don't follow the standard residential buy-back plans, so the tool isn't designed for that use case.

Will switching retailer affect my solar system?

No. Your solar panels, inverter, and battery don't care which retailer you use. You can switch retailers as often as your current contract allows without touching the hardware. Just make sure your new retailer offers a solar buy-back plan (most major NZ retailers now do).

What about time-of-use tariffs from Octopus and similar?

The Engine handles time-of-use plans properly by modelling when your solar typically exports (mostly midday). If you also have a battery and shift export to evening peak, you can adjust the export-timing input and the Engine will recalculate. This is where smart tariffs can really shine.

Why doesn't the Engine ask for my email?

Because we don't need it. The tool runs in your browser, the results are for you, and we'd rather earn your trust than your inbox.

What to Do Next

Once you've found the retailer offering the strongest buy-back for your situation, you've got a few sensible next steps:

• If you don't have solar yet: combine your Engine results with a generation estimate for your region and roof using our Cost & ROI Calculator. That gives you the full financial picture, not just export earnings.
• If you're ready for quotes: head to our free quote-matching service to get matched with up to three vetted installers in your region.
• If you're already on solar but on the wrong plan: ring your current retailer and ask them to match the best rate, or switch. Switching in NZ is genuinely straightforward.
• If you want to brush up on the jargon (buy-back rates, net metering, time-of-use, demand charges), our Solar Jargon Buster has plain-English definitions for the lot.
• If you're not sure where to start: head back to The Solar Advocacy Hub and pick the path that fits where you are.

The Engine will be here whenever you need it. Bookmark it, share it with the neighbour who's been umming and ahhing about solar for the past year, and use it as your reality check whenever a retailer claims to have "the best solar rates in the country." Now you can actually check.