The sun looks set to shine on solar power as batteries come on line.
Recently Meridian Energy and Contact announced they will reduce their payments for electricity supplied by new customers with solar PV (photovoltaic electric) installations.
It was quite a drop, 72% for Meridian's summertime rate.
Hamish McNicol (Stuff, November 6) suggested that ''shadows have been cast on the solar power industry''.
Perhaps, but any setback is likely to be short-lived.
After all, the solar industry in New Zealand has been growing spectacularly in recent years.
The number of applications to install solar PV has increased by a factor of three or four each year, the Green Grid research programme said.
Admittedly, there were just 1200 applications in 2013, and compared with other countries, the installed capacity of solar PV per person in New Zealand is low, less than 2% of Australia's in 2013.
On the other hand, if anything like the historical growth rate can be maintained, solar PV would have a significant impact on the electricity grid by 2020.
The reason New Zealand is behind other countries is that most have subsidised solar PV in the past.
This was done by offering consumers attractive ''feed-in'' tariffs for their surplus electricity, the aim being to increase the availability of renewable energy in these countries.
New Zealand is already well endowed with renewable electricity, such as hydro-power, so has not introduced this kind of encouragement for solar.
As solar PV costs fall globally, the need for such subsidies is disappearing, so we can expect to hear less of ''feed-in'' tariffs in the future.
In this situation it is surprising that there is already a considerable appetite for solar PV in New Zealand.
The Energy Cultures research programme at the University of Otago found that 25% of respondents in a household survey wanted some form of grid independence.
It also found that money savings were not the sole motivation for those installing solar.
This suggests that, like Peter Strang (letter ODT, November 7), they want to ''collect power from the sun ... and stuff the grid and the power companies. Yay!''
So it is unlikely Meridian and Contact will put many people off solar PV.
Further into the future, it looks like distributed solar technology will increasingly favour the consumer seeking better energy choices.
There is growing demand for battery electric equipment globally: laptops, lawnmowers, chainsaws, motorbikes and cars.
This is bringing economies of scale to storage batteries.
As their cost falls, batteries are also being used to store surplus solar electricity, reducing the need for attractive ''feed-in'' tariffs.
Some analysts suggest that, within a decade, solar power generation and battery storage will be commonplace for both residential and commercial consumers and bring downward pressure to bear on the price of grid electricity.
Arguably, as the supply options for consumers grow, the monopoly historically held by the network companies will weaken.
We will still need the grid, but it will be different and the utilities are likely to become charming, more flexible and smarter.
• Emeritus Prof Gerry Carrington is a fellow of the Royal Society of New Zealand and the Institution of Professional Engineers of New Zealand. Each week in this column, one of a panel of writers addresses issues of sustainability.
