Daydreaming in the sun

Cover graphic for Te Mauri Hiko ? Energy Futures

For the next instalment of our look at the?Te Mauri Hiko ? Energy Futures?White Paper produced by Transpower, we will skip over the small fact that very little of this extra electricity would be needed if we simply keep on using petroleum products for heat, industrial processes and transport.

Of course, we cannot do that as Shaw has declared “Zero Carbon” and Ardern has killed the oil and gas industry so we will play their little game and examine their figures.

Whaleoil has taken Dr Woods, the Minister for Energy and Resources to task over her selecting one sound-bite from this document and telling Parliament that all we need is 4.5 windfarms per year.

The document actually says: Quote.

To keep up with demand growth, New Zealand will need material growth not only in grid-connected power stations, but also in distributed and utility generation.

The base case estimates have projected distributed solar PV generation growing to 16 TWh by 2050. The analysis assumes that ~1.5 million houses install solar panels on their roofs and conservative increases in the generation potential of panels through time. The remaining additional supply needed would have to be filled by utility-scale investors, who are anticipated to provide 16 TWh of wind, 11 TWh of geothermal, 6 TWh of solar and 6 TWh of hydro generation.

Marine and off-grid supply make small contributions, and gas and coal-powered generation is assumed to be fully retired.

Exhibit 10 shows that geothermal, solar and wind generation is estimated to make up over 80 per cent of the supply growth. Geothermal is an attractive means of providing baseload generation, and recent innovations are helping to make it more climate-friendly. End quote.

Te Mauri Hiko ? Energy Futures 
Te Mauri Hiko ? Energy Futures

Let’s take a look at the PV numbers above: Approx 1.5 million households with solar panels generating 16TWh.

The 2013 census found 1,549,890?households. StatsNZ predict 2,244,000 by 2038. Let’s say 2,500,000 by 2050. The document is assuming that 60% of NZ households will have rooftop solar panels. Quote.

Nationwide 63.2 per cent of people today live in their own home – the lowest rate since the 61.2 per cent recorded at the 1951 Census – whereas 33 per cent live in a rental.

Statistics New Zealand Dwelling and Household Estimates data released today showed of the 1.8 million homes, 1.2m were owner-occupied in December 2016 and 604,900 were renting. End quote.

Thus the White Paper is suggesting that 100% of privately owned homes will install PV panels. This is a tad tricky if the privately-owned home is an apartment – but we will gloss over that. I cannot see many landlords paying for solar panels for their tenants – but it quite likely that the NZ First led CoL could insist that they do.

Assuming nirvana arrived and all 1.5 million private homes added solar panels. Would that supply 16TWh per year?


I live in the sunny Bay of Plenty, my roof is not perfectly angled to the sun but it is pretty good. I have a 3 kW array which occupies most of the available sun-facing areas of the roof. Over the last 5 years the average output from this array has been 3.8 MWh per year. Multiply this output by 1.5 million and the answer is 5.6 TWh per year or about 35% of the target.

Many areas of New Zealand do not get the number of sunshine hours the Bay of Plenty gets. Many roofs are not well aligned (northward) to the sun. The sun does not always shine; 2018 was only 86% of the output of 2015. And so on.

As much as they may wish it to be so, it seems that 16TWh of electricity from solar panels on 1.5 million households is a pipe dream.

OK, there will be some panels on schools, factories, shopping malls etc as well but will that make up the 65% deficit?

The White Paper also says “and conservative increases in the generation potential of panels through time“.

Will the installation of new, more efficient panels offset the loss of efficiency over time of the existing panels? Enquiring minds would like to know.