With Diwali fast approaching, Vector ramped up PR for its $10 million Auckland Harbour Bridge light show.
The Indian festival of light (Oct 18 - 21) will again see the bridge lit up by 90,000 LEDs.
The first bridge light show was on January 27, with the lines company promoting it heavily as a demonstration of new-generation power.
An animation on Vector's website, says "The sun's rays are absorbed. Solar energy charges the battery. Power is released from the battery to power 90,000 lights on the bridge."
A light show contractor in a Vector video makes the same claim, and the proximity of solar panels and a half-megawatt Tesla battery to the bridge (they sit at the neighbouring North Wharf at Wynyard Quarter) reinforces the impression that the Vector Lights are powered by the sun.
But in the opinion of power expert Brian Leyland, Vector is "seriously misleading the public."
A source at Vector forwarded Leyland a diagram showing the Vector Lights are fed by the grid - that is, the lines company's traditional power network.
The lines company has, inadvertently, created a situation uncannily similar to one of the central plot developments in Solar, the comic novel by award-winning author Ian McKewan about a corrupt scientist turned celebrity alternative-power consultant.
Vector communications manager Elissa Downey confirms the multi-million-dollar light show is in fact fed by the grid, but she says that the amount of power is relayed to North Wharf, and that the battery then releases that amount of power to the grid.
"Meters on the bridge transmit how much energy the event lights are using to Vector's control system. Vector's control system monitors this every 10 seconds and adjusts how much energy the battery is discharging to match. So there's a direct correlation between how much energy the bridge uses, and how much solar-derived energy is released to the grid," she says.
Vector calls this "peer-to-peer" technology.
If you dig far enough into Vector's website, that information is there.
But in Leyland's view, it's greenwashing or a misguided or exaggerated "green" initiative. It's unlikely many - or any - members of the general public know that "peer-to-peer" means the Tesla battery is not, in fact, powering the light show.
Apart from the fact the battery is just spreading power into the general grid, Leyland says information leaked to him by a Vector engineer indicates its very expensive power - a poor advertisement for solar.
"All the solar cells do is provide expensive energy to charge the battery," he says.
"The energy is stored in the battery and, after about 10 per cent loss, is exported into the system when somebody in Vector decides to do so. The cost of storing the electricity in the battery is quite high – at least $0.20 per kilowatt hour."
All up, he says, the solar panels/Tesla battery setup provides electricity at about $0.15 per kWh - "which is twice the average cost of purchasing the same amount of energy from the grid."
Downey says the solar panels at North Wharf produce enough energy to power the 90,000 LED light show; in fact, "more than required."
So why not connect the Tesla battery directly to the bridge, as the company's promotional material implies?
"Vector Lights is designed to be an evolving showcase of current and future smart energy technology, integrating solar, battery and peer-to-peer systems. Using conventional direct connection is inconsistent with that vision, not to mention an unnecessary expense, given there is existing capacity in the local network," Downey says.
"And even with a direct connection, an alternative connection to the grid would have been necessary for continuity of supply," she adds.
"As we've seen with the jet-fuel pipeline, relying on a single, direct connection can lead to problems. We're also avoiding extensive roadworks, disruption and cost by utilising peer-to-peer technology for the existing network to connect between Wynyard and the bridge."