The wind-storm which smashed Auckland in April could be the motivation people need to consider using solar power in homes, a leading energy researcher says.
Dr Kiti Suomalainen, of the University of Auckland's Business School, says the storm - which at its height left over 100,000 homes without power, some for more than a week - was "a reality check" for the city's electricity network.
"If we believe storms like this are going to occur more frequently in the future, then the resilience of the electricity supply becomes an issue," she says. "This as much as economics will be more and more on the minds of people – and is motivation to look at solar as an alternative."
She says advances in battery technology mean households with solar have the ability to keep the lights on during power cuts by storing excess power for use during an outage - or providing the option to power key household appliances.
Suomalainen also believes the storm could prove to be a catalyst for the government to look at introducing incentives to install solar power systems. At present no subsidies are available in New Zealand but, she says, "if we are going to get more of these types of storms, it might be a good time to look at this, as we are lagging well behind other countries in the use of solar."
Suomalainen, a research fellow at the university, has been investigating the potential for the residential use of solar power in Auckland for several years. She has developed an online tool allowing homeowners to find out whether installing solar panels on their roof can save them money – and identifying where the best locations are for harnessing solar.
Her work shows areas like Botany Downs and Flatbush in eastern districts of the city and Massey in the west are among the best locations, rather than other more fashionable suburbs.
"A lot of leafy suburbs aren't that good for solar," she says. "Because they are leafy, the trees shade the rooftops – and a lot are also built on hilly terrain which can reduce the amount of sunlight reaching the roofs."
Her comments come as new statistics show solar power contributes just 0.2 per cent of the country's overall electricity generation - energy which is powered by more than 19,000 solar systems, almost 18,000 of which are residential.
Although Suomalainen says there is "certainly room for increasing the use of solar power in New Zealand", she does not agree it should be made mandatory for new homes as is the case in some parts of the world. In the US for example, the California Energy Committee last month announced it is making it compulsory to fit solar panels on most new homes from 2020, part of that state's efforts to combat climate change.
Suomalainen says she would not go as far as recommending the measure for new
buildings here because "the drivers for it might be quite different from California.
"If the motivation is to fight climate change, then it makes sense to first fight this in other sectors in New Zealand such as transport, industrial heat and agriculture."
However Suomalainen say new home designs could be 'smarter': "I wouldn't mind seeing standards in place for preparing all new builds with technical requirements for new technology like solar panels, residential scale batteries and electric vehicles (EVs) in mind," she says.
"Ideally when an architect or builder designs a house and decides where to put a kitchen, they could similarly design for an EV charging point for example; new buildings could also have a hot water cylinder designed to work well with solar, possibly one that already comes with a solar diverter.
"I don't see it being relevant in New Zealand to mandate certain technology adoption, but I do think building standards could be in place to prepare for these technologies."
Suomalainen says her online model shows that if all Auckland roofs were covered in solar panels 180 per cent the city's power needs could be generated.
The model has been built by using council data collected by planes emitting light pulses, similar to how bats use sonar. These pulses are timed to see how long it takes for the reflections to return to the plane.
"Knowing the speed of light it is possible to calculate the distance to the plane of the object it reflects from," she says. "If you know the location of the plane you can calibrate and build a 3D image of the surface of Auckland as seen from above."
The model also has an online calculator that crunches the solar rooftop potential of buildings down to a square metre. It allows users to zoom in on their roof-top for a colour-coded view of its solar energy potential and highlights the best spots to place panels.
Homeowners can also enter the size and quality of solar panel they prefer, how much solar power they would use – and how much they would sell back to the grid.
She says the amount people could save on electricity would depend on these variables – and on the price of electricity and whether they are renting or have bought solar panels.
"But generally you tend to save money as long as you are consuming all the electricity you produce yourself," she says.
# Solar is expected to account for 29 per cent of the world's electric capacity by 2040, up from four per cent at 2015. According to the International Energy Association (IEA), solar power grew faster than any fuel in 2016. China is expected to add 40 per cent of the world's new solar panels between now and 2022.