DIY power house has surplus

By RICHARD WOOD

Viola and Phil Palmer have not had a power bill for seven years.

When the contractors on their Kapiti coast house removed the temporary service line, they severed all connections to the national grid.

The couple make all their own power, using a wind turbine and solar panels, feeding a bank of storage batteries.

When the sun is shining and the wind blowing, they make more power than they can use, up to about 2kW.

The Palmers could be selling this surplus to their power company but metering and line charges make it uneconomic for such a small quantity.

"There are a number of issues that the industry has to resolve before we can introduce a policy on buying power from small generators," says Contact Energy metering business manager Duncan Craig.

"One issue is the size of the generator. Small generators will need to be processed differently from larger ones.

"The core business of lines companies is to charge for power sent on their lines. Some may not be prepared to accommodate very small generators, while others will be very keen."

The Palmers, both semi-retired professionals, do not need to save power; neither did they need to count the capital cost of becoming energy self-sufficient.

They do not talk about what it cost them, but they did estimate a 20-year payback period (multiply a two-person household power bill by 20 years to get an idea).

The eco-house is their personal stand to protect the Earth's diminishing natural resources.

"By becoming self-sufficient in electricity we are not part of the process that requires rivers to be dammed or fossil fuels burned," says Viola.

They live on 2.5ha in the suburbs only 5 minutes' drive from a shopping mall.

Their home is architect-designed and has all the modern conveniences, with a few exceptions: no electric blankets, dishwasher, clothes dryer or electric heater.

Their power runs the following devices and appliances, via a 230v AC system: double automatic garage doors; workshop with circular bench saw; office with computer, phone, fax; freezer and fridge; washing Machine; water pump; vacuum cleaner; microwave oven and kitchen appliances.

In the garden is a two-bladed 1kW wind turbine atop a 9m pole. The Palmers are far enough from neighbours that the propeller noise does not cause annoyance.

Twelve solar panels on the roof produce nearly 1kW/h on a good day.

Both sources feed into 12 linked, deep-cycle batteries that will store power for 10 days without a top-up.

The power is stored as 24v DC. It has to go through a 2000W inverter to be converted to 230v AC power for the household system.

Water is heated via solar panels and a wetback-equipped woodburner. Cooking is done on a gas hob and oven, fed by LPG bottles. The woodburner also has a cooking top.

The interior temperature of the house is controlled by a combination of insulation and double-glazing, the woodburner, and concrete and stone floors, walls and pillars that absorb heat during the day and release it slowly at night.

Anything that produces heat from electricity is a big power user, even the electric jug, says Viola.

On sunny, windy days the solar panels and wind turbine generate so much power that they often have to waste it, via a heating element in the hot-water cylinder, and a heating coil on the garage wall.

At times the system does get overloaded. Extra people can use all the stored hot water, in which case the Palmers have a backup gas-heated cylinder in the guest house, and the woodburner can be cranked up a gear.

The only time they could not cope was when an upholstery cleaner came to shampoo the lounge suite and the big commercial machine wanted more power than the couple could provide.

Mrs Palmer said: "My advice to the Minister [of Energy] is: bring back planning, get your hands on the controls. Insist on power companies sourcing a percentage of their supply from alternative sources, i.e. wind and solar. This is a requirement in Germany."

Home-made power

Viola and Phil Palmer make their own electricity.

They have: double automatic garage doors; workshop with circular bench saw; office with computer, phone, fax; freezer and fridge; washing machine; water pump; vacuum cleaner; microwave oven and the usual kitchen appliances.

They don't have: electric blankets, dishwasher, clothes dryer or an electric heater.