Conservation Comment: Warming to solar energy use

SUN POWER: Solar power panels on the roof of a newly-built home. PHOTO/FILE

By Lorna Sutherland

THERE has been debate about the value of solar panels as a source of "green" energy. No surprise there, people interested in moving energy production away from carbon-based fuels want to get things right. So they challenge proposed methods.

A December 6 report in Nature Communications (a peer-reviewed, open access scientific journal) by Wilfried van Sark, and colleagues of Utrecht University attempts to clarify, and put some numbers into the picture. The report, "Re-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development", was the subject of an article in the December 12 Economist titled "Solar energy Shine on". The original paper is easy to find.

I have fished out the punchlines.

Where and when solar panels are made matters. Manufacture has become far more efficient in the last 40 years. European manufacture is presently more efficient than Chinese.

Where they are installed matters too. China relies more on fossil fuels for generating electricity, so the clean power solar panels produce replaces dirty power and thus gives greater environmental gain.

For every doubling of the world's solar capacity, the energy required to make a panel fell by about 12 per cent and associated CO2 emissions by 17-24 per cent.

Depending on how the numbers were crunched, global break-even for silicon-based solar panels could have come as early as 1997. But even the most pessimistic assumptions expect it to do so in 2018. After that solar's environmental credentials will be spotless.

That is the big picture, but how does solar fit into New Zealand?

Figures from 2015 say solar contributes 0.1 per cent to our total energy production.

We have no subsidies, and about 80 per cent of our electricity is generated from renewable resources. Our electricity companies have reduced the amount they will pay for photovoltaic (PV) energy that is fed back into the grid. A 2015 New Zealand study found that solar was more economical than grid supply if all the electricity was used on site.

Solar panels have a life expectancy of 30 years, and virtually no maintenance costs. A storage system (battery) does though. According to Wikipedia, the 2009 average NZ price for a three-kilowatt (3kW) photo-voltaic system was about $40,000. This has since dropped by 75 per cent to $10,000.

According to friends who have lived on solar for the past 10 years, 3kW will run a washer, fridge, lots of LED bulbs and plenty of whistles and bells. They think it would probably handle a heat pump dryer too, because they generally have surplus electricity, but their hot water comes from a separate solar system. They heat with wood and cook partly with gas.

It would seem an earthquake-prone country would do well to encourage as much resilience in electricity production from clean sources as possible in a time when more extreme weather events are expected.

Because PV is viable on a small scale, it could be a useful part of this resilience.

�Lorna Sutherland has lived in many different places and observes the changes in the natural environment around her.