Solar energy

Solar electricity systems (also known as photovoltaics, PV systems, or solar panels) convert sunlight into electricity through solar panels on your roof. When sunlight reaches them, semiconductors in the panels create an electrical current, which is then converted into a form your household appliances can use – anything from toasters to spa pools. 

Most homes with solar power are also still connected to the electricity grid (‘grid-tied’). That means you can still use power from the grid as a backup when your solar energy system isn’t generating enough for your needs, or at night. 

If you’re grid-tied, any excess power you generate gets sold back to the electricity grid – although ‘buy-back’ rates are typically a lot lower than what you pay for electricity. It’s generally better if you can use all or most of the power you generate.

Solar panels can still generate electricity when it’s cloudy or raining, but it’s much less efficient than when the sun is shining. You can also store excess solar energy for use when the sun isn't shining by adding batteries to your solar power system – more on that below. 

It depends on a range of things, including your home, how much power you use, and how and when you use it. And while solar is suitable in most parts of New Zealand, it’s a particularly good option in sunnier regions like Northland, Auckland, Nelson, Bay of Plenty and Marlborough. 

You get the best return on your investment in solar power if you can use as much as possible of the power you generate. That’s because the price you receive for selling electricity back to the grid is generally lower than the price you pay to buy electricity.

Most solar power is generated during daylight hours, so solar is usually cost-effective if you use a lot of electricity during the day or can store the energy overnight, for example in an electric hot water cylinder. If you’re working from home, you’re charging an electric vehicle, heating a spa pool or similar, solar can be a great option. Shifting your ‘normal’ power consumption e.g. by using timers or setting things like dishwashers or washing machines to run during the day can also increase cost-effectiveness. 

Solar panels obviously work best when they get as much sun as possible. So consider whether your roof is in shade from trees, other buildings or might be in the future. 

You should also consider the condition of your roof – once solar panels are installed it’s difficult to do roof maintenance or repairs so consider whether your roof will last as long as the solar energy system. 

It’s also important to remember that before you consider installing a solar energy system, that you’ve invested in adequate insulation, efficient heating, coverings or double glazing and that you have sealed any draughts and filled any gaps in doors and windows.

The Gen Less solar tool could help you assess the estimated financial return of solar electricity for your home.