Solar power can be part of the solution

20:40, Aug 05 2012

Guy Waipara of Meridian Energy disputes a report evaluating solar water heating by the Parliamentary Commissioner for the Environment, Jan Wright.

I agree that solar hot water heating is no 'magic bullet'. Anyone who has been around the energy sector for a while will know that you are just as likely to come across a perpetual motion machine or a money tree growing in your back yard.

The major drawback with the Parliamentary Commissioner's report and its analysis is that it focuses on whether solar power operates at the very half hour of the coldest day in winter. It rightly concludes that it doesn't, but it wrongly concludes that this is critically important.

What is important to understand is that energy can be stored for later use and meeting peak demand is neither the critical problem, nor the problem for one technology to solve in New Zealand's electricity system.

Solar hot water systems convert solar energy to hot water which is stored for later use in hot water cylinders. The fact that this conversion happens during the day and not at night does not diminish the value it provides in offsetting the use of fossil fuels in either gas or electrical heating systems.

Using less gas has obvious benefits. Using less electricity to heat hot water means we generate less electricity and instead are able to store that in the form of water in our North and South Island hydro lakes. There are parallels to the way in which wind and hydro generation are complementary resources. In simple terms, hydro can be used when the wind doesn't blow. The same applies when the sun doesn't shine.


The focus on peak demand is also misleading. The fact that the majority of New Zealand's electricity system is hydro-based means we have a much larger margin or excess of peak generation capacity than many other power systems.

For example in 2011, the country's total installed generation capacity was around 47 per cent greater than national peak electricity demand. This includes a mix of generation options to meet peak demand and the majority of it is hydro.

So if you replace the search for a magic bullet with, say, magic buckshot, then solar power, whether it is used to heat water or generate electricity, alongside wind, hydro and geothermal energy, can provide part of the solution to an economic renewable energy future for New Zealand.

Guy Waipara is Meridian Energy's general manager external relations.

The Press