Editorial: Solar flares up

It's not all sunshine and light being the Parliamentary Commissioner for the Environment. Just ask the country's current chief green guardian, Dr Jan Wright.

In the latest report from the commissioner's office on matters affecting the environment, Wright argues that solar water heating will not be the white knight galloping to rescue New Zealand from the threat of missing its self-imposed renewable energy targets.

More broadly she concludes that widespread uptake of the technology will not save the environment, neither will it do a lot to reduce carbon dioxide emissions linked to climate change.

Wright also frames her views in the context of the post-earthquake rebuild of Christchurch. She questions the wisdom of a Christchurch City Council energy strategy encouraging and subsidising solar water heating and cautions against the widespread adoption of solar water heating in the city, referring to the plans of the developers of the 2200-home Highfield subdivision to install solar water-heating systems and photovoltaic panels on roofs.

Such strong conclusions have unsurprisingly drawn the ire of those in the solar energy industry. Wright has also been challenged from an unusual quarter, with Green Party energy spokesman Gareth Hughes saying her report did a "disservice" to the technology. It's certainly a strange state of affairs when the Greens take issue with the nation's top environmental watchdog.

Wright predicates her argument on the need to reduce winter demand peaks. She says unless those peaks can be flattened, the desire to generate 90 per cent of the country's electricity from renewable sources is heading for failure.

Unfortunately, when power demand peaks on the coldest and often wettest or snowiest days of winter, solar water heating will be of little use, as the sun is also at its weakest then, she says.

That means that as long as there are winter peaks, new power plants will be required to generate that extra electricity. Such developments will "lock in" new sources of carbon dioxide for decades.

Wright instead wants to see more widespread promotion of night-only water heating, when demand for electricity is lower, to reduce peaks.

She also expresses a need for greater use of ripple control and further development of the smart grid and smart meters to reduce peak loading.

Solar power company SolarCity believes she is "out of step” with the views of the International Energy Agency, which has calculated that solar thermal power could meet one-sixth of global demand for heating and cooling, potentially saving 800 megatonnes of carbon dioxide emissions a year by 2050.

In her report, the commissioner makes some good points about carbon dioxide emissions and quite rightly says New Zealanders will have to do much better if we want to get anywhere near the 90 per cent target. But she concludes that solar water heating does not yet provide the "magic bullet".

Wright's analysis of course is at the macro-level, providing a broad overview of the issues. At this stage, what she has determined is probably best left to energy companies, government departments dealing with energy efficiency and local councils to consider.

Perhaps in 10 or 15 years' time, if a way has been found to efficiently store solar power, it may be a different story for homeowners wanting to embrace the technology.

The Press