Within a decade the owners of solar-powered homes in sunny Poverty Bay, Hawkes Bay and Nelson will probably be able to generate their own electricity cheaper rather than buying it from the grid.

Experts say, in various reports, that will be a distinct possibility -- at least during daylight hours.

Early adopters are showing what can be achieved, with an investment of around $10,000. Hawkes Bay couple Jenny and Philip Povey have cut their bill after installing a 3500-watt solar system on their home's roof. Winter bills are down from $250 to $90 a month, and to just $60 in summer. On some days, they sell power to the grid. There are around 2000 such homes nationwide.

The problem is power lines are not cheap to erect -- making up 39 per cent of the total power cost nationwide, says a study by the Canterbury University Electric Power Engineering Centre.


Perhaps concerned about a few users becoming thousands, Hawkes Bay lines company Unison slammed all low power users -- including solar home owners -- with an increase of up to $150 a year.

In a statement, Unison said its costs were based on providing power during winter evening peak periods when solar panels are not helping.

The Poveys' large 1980s house is insulated, but has a cathedral ceiling. It has two heat pumps, mostly for summer air-con, electric hot water (turned off overnight), power stove and wood burner. Even by cooking during the day and microwave reheating, they need to buy power.

Jenny Povey is yet to get her first new bill.

"Why should we be treated differently from any other low user?" she says. She is considering installing batteries, but their house would have to stay plugged-in during the winter. Unison's release indicates all low users will be charged the increased rate.

But the trend is inevitable. The falling cost of solar power is a 'disruptive technology' for power companies. Within a decade, about 18 per cent of homes may have solar power, says a report by Concept Consulting Group ('Electric cars, solar panels and batteries in New Zealand' is free at Concept.co.nz).

In Gisborne, Hawkes Bay and Nelson, the tipping point will be earlier. Some banks (such as Kiwibank) may already add the installation cost to your mortgage.

While many home owners will convert to solar power -- most will still need to remain grid-bound. Although the cost of solar batteries is falling, the Concept study says it may take two decades for battery costs to get economic. But if too many users leave the network, line companies' revenue will fall while their costs are fixed.

After Unison's price hike release, there were complaints to the Electricity Authority and the Commerce Commission. The Electricity Authority found Unison was within the law, but began a consultative process.

Not all submissions are pro-solar. Consumer NZ says most people can't afford to install solar, so charges should not favour the better-off. But Green Power expert, Canterbury University's Dr Allan Miller says installing home solar power is your right. "I think it is an individual choice if people want to put in solar power," he says. "I see solar power as something people want to do."

The Electricity Authority does not see "mass disconnection" for many years, and even hints prices may fall. "Distribution networks and most electricity generation in this country have very low operating costs. As a result, electricity generators and distributors can reduce their prices in response to competition from other technologies -- good news for consumers," said chief executive, Electricity Authority Carl Hansen.

He says 80 per cent of New Zealand's power is produced renewably -- Kiwi power is very green, although the system burns carbon on cold nights. Even solar homes must rely on carbon backup -- unless they have batteries.

The Concept report reckons it could take 20 years before batteries in houses will be economic -- but power companies may install their own before then. Electric cars are also falling in price, and many are powerful enough to run your eco-friendly home. The car recharges after you hit the hay.


If you want to reduce your carbon footprint, you are probably better off buying an electric car before installing solar power. Green Power expert, Dr Allan Miller crunched the numbers, so he and his wife, Charlotte bought an electric car rather going solar.

The Nissan Leaf costs just $40 a month to run, using a cheap night rate, versus $250 a month on petrol, saving about $200. There is no petrol tax on electricity, just GST. Software starts re-charging off peak.

"It is a fantastic driving experience. It feels good to drive a car that doesn't contribute to the greenhouse effect," he says.

As Charlotte drives the car to work, there would be little point in charging it from the house, Miller says.