Solar photovoltaic systems are normally installed with a grid-tied configuration, which allows you to draw electricity from either the power network or the solar array without using a physical switching device. If your solar system is producing surplus electricity, it is exported to the grid in exchange for a feed-in tariff. On the other hand, if your consumption is higher than solar generation, the difference comes from the grid.
Since a grid-tied installation involves exporting kilowatt-hours to the network, there are technical requirements to meet. It is important to have an automatic disconnection system, to be used whenever there is an electric service interruption. If reparations are being made on distribution lines or transformers, and your solar PV system injects electricity to the grid, the technicians working outside may experience an electric shock. The consequences can range from minor injuries to fatalities, so prevention is extremely important.
All grid-tied solar power systems require approval in New South Wales, but the procedure is automatic for installations with an inverter capacity up to 5 kW. For systems with larger inverters, the application requires individual approval and there may be additional fees depending on the network service provider.
If the solar power system uses batteries, there are additional factors to consider for project approval:
Regardless of whether a solar power system is eligible for individual approval, the installer must deliver a Certificate of Compliance for Electrical Work (CCEW). Two copies are required, one for the client and one for the network provider.
Some older buildings have power meters that are not suitable for grid-tied solar power systems. Consider that electricity can flow in both directions once you have a photovoltaic array, and older power meters are not capable of bi-directional measurement. If this is the case in your property, you must upgrade to a smart meter.
Many network providers install smart meters for free, but there are still exceptions. Solar power providers can normally include a smart meter in their proposal, for clients that cannot get them free of charge from their electricity provider.
Although a grid-tied solar power system lets you export surplus generation to the network, your power bill savings are higher when you consume the full output of the photovoltaic array. When you export, you get a feed-in tariff that is only a fraction of your electricity tariff, but you save the full price of each kWh when solar generation is consumed. Also keep in mind that feed-in tariffs are being reduced between 2018 and 2019, making exported energy even less valuable.