Are Vector’s solar claims a bridge too far?

Expert questions if light show on Auckland landmark is really powered by the sun All the solar cells do is provide expensive energy to charge the battery.

With Diwali approaching, Vector ramped up PR for its $10 million Auckland Harbour Bridge light show.

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 halfmegawatt Tesla battery to the bridge (they sit at North Wharf at Wynyard Quarter) reinforces the impression the 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 — the lines company’s traditional power network.

Vector communications manager Elissa Downey confirms the multimillion-dollar light show is fed by the grid, but says the amount of power is relayed to North Wharf, and 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 it “peer-to-peer” technology. Leyland claims it’s greenwashing or a misguided or exaggerated green initiative. It’s unlikely many members of the public know “peer-to-peer” means the Tesla battery is not 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 it’s very expensive power.

“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.”

He says the solar panels/Tesla battery setup provides electricity at about $0.15 per kWh “which is twice the average cost of buying 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-topeer 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. “Even with a direct connection, an alternative connection to the grid would have been necessary for continuity of supply.”