Shining light on a viable alternative

22:01, Aug 21 2009
A RAY OF SUNSHINE: Research scientist Tim Kemmitt says New Zealand is not utilising its solar-power potential. He suggests we embed millions of hi-tech solar cells on the roofs of our homes, warehouses and offices to pump power into the national grid.

New Zealand is far from a star when it comes to tapping our world-class solar resources, says a leading scientist.

"We're lagging behind. At the moment, in Germany, about 10 per cent of the electricity generated is solar, and we get far more sun than Germany," says Industrial Research Limited senior scientist Tim Kemmitt, who believes government subsidies encouraging solar power generation are needed if we are to make the most of our sun.

According to Niwa, most regions get 2000 sunshine hours a year.

Dr Kemmitt says that, though we have plenty of renewable hydro energy, that hasn't helped us explore options such as solar.

His answer? Millions of hi-tech solar cells embedded on the roofs of homes, warehouses and offices, all discretely pumping power into the national grid.

Made from quantum dots nano-sized particles of semiconductor material the cells are many times more efficient than normal solar panels.


The cost of generating solar power is high but falling. According to the Energy Efficiency and Conservation Authority, in 2004 solar generation cost up to $17 per watt installed.

That meant a 2kW system cost almost $40,000. By last year that fell to between $9 and $13 per watt installed, so a 2kW system cost $18,000 to $26,000.

It is possible to put solar-generated electricity back into the national grid, using a "grid tie" system that can cut your power bill.

They can range from $10,000 to $70,000 with a payback period of up to 20 years, though this is dropping.

Dr Kemmitt hopes solar generation costs could be cut further by embedding the dots in lost-cost panels and placing them close to population centres, cutting energy losses from electricity transmission.

"If the stuff we are doing in this project works out, we will be in a position to make it commercially viable. You will never need to have another coal plant. There's more energy from the sun than you will ever need."

Dr Kemmitt says the technology is still being developed. "We are very early on so we are not claiming to have solved the world's problems yet."

In Germany, a state support programme has seen it second only to Japan in photovoltaic power generation.

Bob Lloyd, from Otago University's Energy Studies Programme, says solar is a good option, especially for small-scale renewable production.

But wind is often the preferred option as it is cheaper to install. "There's also ignorance. Solar has been very lightly promoted."

Government subsidies would help boost our solar output, he says. "New Zealand could be doing more than it is."

Of our national electricity generation, "a negligible amount" comes from solar generation.

Energy Minister Gerry Brownlee says the Government is focusing on boosting solar water heating with $1000 grants to homeowners, rather than subsidies for national power generation.

Solar power was still expensive to develop, compared to renewable resources such as wind and hydro.

"At the point where solar power is commercially viable, it will become available in New Zealand.

"Our solar industry is very innovative so I'm sure it will happen one day."


Solar energy is the conversion of light into electricity.

Some materials can absorb photons of light and release electrons. When the electrons are captured, the electric current can be used as electricity.

Dr Kemmitt's solar cells have 10 to the 15th quantum dots on an area the size of your fingernail. That's 10, followed by 15 zeros.

Exactly what the cells are made of is still secret, though titanium is one component.

Our solar energy resource is about four kilowatt hours per square metre each day.

If every New Zealand home had a roof covered in solar panels, they would generate enough power to satisfy more than a quarter of our annual electricity needs.


The Dominion Post