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Connecting to the Grid

Grid-connected systems

 

Micro-generation can be used as part of a Stand Alone Power System. It can also be installed if you're already connected to the national electricity grid.

These systems are called ‘grid-connected' or ‘grid-tied', another method of connecting your micro-generation system is ‘grid-interactive'.

Grid connection makes sense in the following situations:

  • you are already connected and buying power from an electricity retailer
  • your new home is very close to power supply lines (98% of new homes in New Zealand are)
  • your micro-generation system will not meet all your electricity needs all of the time.
  • you want to sell any excess electricity back to the grid.
  • You would rather use the grid than purchase batteries and a backup generator.

The most common form of alternative energy power generation is solar photovoltaics (PV). These use solar panels to convert sunlight to electricity. Wind and hydro generation can also used if you have the right resources (ie, a good constant supply of wind and flowing water.)

Usually, a grid-connected micro-generation system is designed carefully so it just covers your electricity needs.

Connecting to the grid

Connection to the local electricity network must be done by a registered electrician. The Solar Panels will be connected to an inverter. The inverter converts direct current (DC) into grid-compatable alternating current (AC). A special meter needs to be installed to separately measure the electricity you export.

Selling electricity back to the grid

Owners of grid-connected systems may be able to sell surplus electricity to an electricity retailer. This means that when the system is generating more electricity than is needed, for example, during a long sunny summers day when no one is home, the owner could be paid for the surplus. Each electricity retailer has their own terms and conditions for buying excess electricity. The price that they offer per kilowatt hour (kWh), called the ‘buy-back' price, will also vary.

Applying for a grid connection

In order to install a grid-connected system an application to the local electricity lines company (sometimes called the ‘network' or ‘distribution' company) needs to be made. This is the company that manages and maintains the lines that deliver electricity to your house.

Local lines companies:

  • Can charge you up to $200 for a connection (for a generator less than 10 kW)
  • Can charge $60 to carry out any onsite inspections of the installation prior to its commissioning
  • Must take no longer than 30 working days to process your application.

Grid-connection standards

Grid-connected inverters must comply with your local network company's connection standards and safety requirements. You may be able to view these standards and requirements on the company's website. AS4777 is one standard that has been adopted by some New Zealand lines companies.

Network companies are likely to approve your installation sooner if you use a compliant grid-connected inverter. Compliance with the standard assures the network company that issues around safety, fault protection and power quality are dealt with.

When choosing an inverter, make sure:

  • It's compatible to connection with the grid and complies with the requirements of your network company
  • Local support and servicing are available.

Connecting to the grid made easy

S4SOLAR offer a ‘one-stop-shop' service. This will take care of connecting your micro-generation to the network, designing and installing your system, and liaising with the network company and electricity retailer.

 

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