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What is Solar power and how does it work?

Solar Power Frequently Asked Questions

How does it all work? 

With solar panels customers can turn sunlight into electricity. This electricity can be used in their home, stored in a battery or exported back to the grid. This export can then be purchased by retailers like Mercury. This is known as distributed generation, import/export, Buy-Back or embedded generation.

What do you need to know before you begin?

You must have written approval from your lines company, to be able to export power from your property onto their network. You can find your lines company contact details here

What happens once I have approval from my lines company?

Once approval has been given by your lines company to export power from your property, email our connections team along with the attached meter installation application and lines company approval to


What do I need to know about metering for solar power?

Do I need to install a special type of meter? 

In order for us to record your usage and output, you’ll need to install an import export meter.

What do I need to do to get an Import/Export meter installed?

You will need to get the network Company’s approval before doing this.
Once you have received the networks approval we can install the meter and then you can arrange to have the panels installed. To get the meter installed you will need to contact our Connection Centre to arrange this.    

How long will this take? 

Single phase – Auckland 2-4 working days from application. Outside of Auckland: 30 working days from application.
Three phase – Auckland up to 5 working days from application.

Will a smart meter be installed? 

Yes, but Mercury will read the meter manually and the readings will not be available on your GEM account.

I already have a smart meter why do I need another meter installed?

Your current smart meter is not configured to record the export usage.

What happens if I turn on my generation’s system before the import/export meter is installed?

You will not receive any credit for any generation as we will be unable to calculate this. There may also be an impact on your usage.

What is an import/export meter?

This is a meter with two registers, one to record the import usage from the network and one to record the export usage to the network. These are also known as Buy-Back or 2-way meters.

What are the costs involved? 

The cost of having an import/export meter installed and to have the ability to export electricity back to the grid is currently $99 incl. GST.

Do I have to have a Buy-Back meter if I have a generation system?

If the system is capable of generating excess power to the grid then you must have a Buy-Back meter installed. This is industry regulation.

When will my Buy-Back rates start?

The Buy-Back rates will be applied from when the Buy-Back meter is installed. We are unable to calculate the Buy-Back prior to the meter being installed.

Where do Mercury offer Buy-Back rates?

Available nationwide, with the exception of two networks; Network Waitaki & The Lines Compay.

What will Mercury pay me for any energy I export?

Any power exported will currently be bought off you at a rate of 8 cents per unit. (Subject to change). (Excluding GST and discounts).

Will I be able to continue on my contract rates?

No. Our standard solar rates will apply from when the new meter is installed. If the customer is on a contract a break fee will not be charged.


Why is Mercury is attempting to charge GST on a Gross figure and ignoring household generation Buy-Back usage discount?

Mercury is required to apply GST to its taxable supplies, in your case this is the electricity Mercury has supplied to you.  The electricity that you have generated is considered for tax purposes to be a supply from you to Mercury.  GST can only be applied to the value of this if it is a taxable supply under the Goods and Service Tax Act 1985.  In most cases this will only be applicable if the supplier is GST registered, and the property and equipment used to generate the electricity are business assets.  If you feel this applies to your situation we suggest details be passed on for further review. 

Other information you might find useful:

If you are in a contract with Mercury, once your import/export meter is installed your contract will end, and no termination fees will be charged.


If you have any more questions feel free to contact us on 0800 10 18 10, our Call Centre is open Monday to Friday from 8am until 8pm, or email us anytime at and we’ll get back to you as soon as we can.