The next day, it saves the power at the agreed time.
Meridian innovation manager Grant Sullivan said a customer could save power by shutting down plant, doing maintenance or running a generator.
The system was best-suited to large or medium-sized industrial customers, he said, as they could readily save enough electricity to make it worthwhile and they had sophisticated power meters.
Good meters are required as the electricity saved must be verified before any credit is given.
The company selling the package in New Zealand, Demand Response, verifies the savings on behalf of the customer and Meridian.
The system is run from a head office in Atlanta.
In the United States, wholesale power prices often soar during summer, when people turn up the air-conditioning.
On the hottest days, wholesale prices in some parts of the US can increase 100 fold, putting strain on electricity retailers.
Using this system, retailers offer similarly high credits to big power users if they save electricity at peak times.
Demand Response director Stephen Drew said the system would be pitched to other New Zealand power companies.
But the product is not without flaws, says TrustPower's manager of energy sales, Chris O'Hara.
His company tried to get many of its customers to cut consumption during winter.
Verifying the savings was difficult, he said. Power use could be compared with the same period last year, or against a rolling average, but they might not show real savings.
For instance, if a maintenance period was bought forward by a month, then total power consumption might not change at all.
"Our analysis shows that it is a very difficult thing to do and you may end up rewarding something that isn't real," said Mr O'Hara.
High wholesale prices over last winter prompted all power companies to encourage customers to cut back on electricity.
Mighty River Power spokeswoman Angela Armstrong said that while the company did not yet offer a similar internet-based system, it was investigating "interruptible-load products".
These are similar to "ripple control" on domestic hot water supply. A customer could, for instance, pay a lower tariff in exchange for having a non-essential piece of equipment turned off by the power company.
They would, if necessary, be warned before the power was switched off.
Power to the People Supplement
Energy Efficiency and Conservation Authority
