Rooftop solar

Everyone’s situation is different, and solar may be a better investment for some homes more than others. In addition to the benefits outlined above, some key factors to consider are: 

• You’ll be able to use more of your generated electricity if you can power or charge large energy using tech like an EV, spa pool, and hot water during the day. 
• If you have an EV you could stand to benefit from solar power more than other homes, because of your increased electricity usage (and costs).  
• To use electricity after dark, you’ll need to buy it from the grid as usual or install a battery system that can store your solar generated electricity. 
• If you use a finance option to buy your panels, the interest charged may reduce the savings you’ll gain by using solar electricity.  
• You get better value from using your solar electricity than selling your excess to a retailer.  

Not necessarily. The size you need for your home depends on how much energy you use, and whether or not you have a battery to store it. For the best value, most of the electricity the system generates should be used directly in your home, rather than sold to a retailer. A solar installation expert will be able to advise on the best sized system for you.  

Solar PV panels are suitable for both rural and urban conditions. They’re usually installed on your roof but can also be placed on facades, conservatory rooves, garages or specially built stands on the ground.

Panels should face north as much as possible to maximise the sunlight they receive. They will still work if they face in other directions, but they won’t produce as much electricity. Ideally, panels should not be in shade caused by trees, surrounding buildings or hills.

Solar panels are normally fixed at the angle of the roof. You can buy mounting frames to improve the panels’ angle but sometimes, their cost can outweigh the added benefit.

Talk to a solar installation expert about the best options and solar panel set-up for your home.

Find a SEANZ professional(external link)

Solar panels are expected to last around 25-30 years, with minor maintenance. For best performance, panels should be cleaned periodically to remove dirt and other debris such as leaves. Panels will stay clean for a long time in areas with high rainfall and better air quality. You may need to pay a contractor to do this work if your roof is difficult to access and/or steep. Trees that shade your panels should be trimmed.

It’s likely that you will need to replace the inverter during the life of your system. An inverter converts the direct current (DC) electricity generated by solar panels into the alternating current (AC) used in New Zealand houses. Inverters come in two main types: string inverters and micro-inverters – talk to a solar expert about the best option.

How you choose to finance your solar panels will make a big difference to the financial viability of installing them, as well as the savings you can make from them over time. In short, the higher the interest rate, the lower the savings and the longer the payback time.

For homeowners with a mortgage, there are currently zero interest (or very low interest) green loan options that are available on top of a mortgage. Often these can be paid off well before the warrantied lifespan of the panels.  

Make sure you understand the terms and conditions of any finance provider, and get independent advice where needed. 

Assess the value of solar for you

Learn more about green loans

*Gen Less solar power calculator

The 8-year payback is calculated based on the following inputs to the calculator: 

• Auckland location, and north facing roof with 30 degree pitch 
• Default electricity rate for Auckland, and 10,000 kWh annual consumption 
• Default 12c/kWh export (buy-back) rate, and no additional daily fixed charge 
• Electricity use usually high during the day for more than five days a week 
• Electric space and water heating, washing machine use every second day with a warm wash, and an electric hot water cylinder with a timer 
• A 4kW system, installed for $10,000 inc. GST 
• Zero finance cost, or financed from savings at 1.2% 

**Electric Homes Technical Report, Rewiring Aotearoa, March 2024(external link) and internal EECA analysis. (EECA is the government agency that backs Gen Less).   

While every house and situation will be different, the costs and savings presented here are reflective of an average New Zealand household of ‘2.8’ people, and don’t include finance/interest costs. This household situation could reflect a household with 3 people where the energy and vehicle use per person was slightly lower than average.