Science – Solar: a climate restoration promise

An editorial in the most recent Economist (June 20) explains why solar, an energy source that gets cheaper and cheaper, will make a leading contribution to the pursuit of zero carbon in NZ and across the planet. A silicon photovoltaic (PV) cell is a reproducible item. When the PV cell is exposed to sunlight, a surface charge develops which, when drawn off by an applied voltage, will generate about seven watts of electric power. This year, about 70 billion of these PV cells will be manufactured in the form of panels. They can be attached to almost any architectural structure as cladding to make the building energy independent. The ease with which solar cells can be reproduced, ensures that solar energy will become cheaper as time passes.

Scaled-up solar energy has been deployed in China and India as massive PV farms occupying up to 60 square kilometres of landscape – enough to power a city with clean, silent, sustainable energy. In Thailand, a PV array of 145,000 panels is floated on waterways to capture the solar energy during sunlight hours and then pumped off by turbines during the night. This type of water-based presentation is called a floatovoltaic farm and the cooling effect of the water makes the PV panels operate more efficiently.

According to the Economist article, over the duration of last year, solar energy produced about 1600 trillion hours of energy, which was 6 per cent of the global energy produced that year. During a single day this year, the world is expected to produce about 700 times the quantity of solar energy produced in the year 2004. This astonishing rate of cheaper and clean energy growth will mean that solar energy will outgrow fossil fuel in any case.

A further advantage of silicon solar energy is that the technology continues to present a variety of opportunities for higher efficiency arising from improved materials and clever designs that capture more sunlight. We are also seeing parallel improvements with wind turbines, so the advantages of combining solar by day and wind by day and night will enhance both energy sources.

In the NZ context, the advantages of solar energy begin with a direct reduction in the cost of household power. The addition of solar panels and a battery to a home will add capital value to the property and will make that property more resaleable. Including a solar battery will enable the difficulties of power outages to be better managed without the need of diesel-powered generators and their associated health risks. Finally, using solar panels to provide power for an Electric Vehicle (EV) delivered via a home charger makes the EV cheap to run compared to petrol cars, petrol hybrids or even EVs powered by commercial fast chargers. This is even true when Road User Charges (RUC) are included, which has been demonstrated by Prof. Shaun Hendy in a recent report in the NZ Herald.