Top Energy has been working with Transpower, which operates the national grid, to identify the cause.
Chairman of Business Paihia's cruise ship committee Heinz Marti said that, while the number of vessels was only eight more than last year, the number of passengers would almost double from 60,000 to 105,000, due to the ships' ever-increasing size.
The benefits were spread across the Far North, he said. On average, a third of passengers pre-booked tours as far away as Hokianga or the glowworm caves at Waiomio.
Another third organised their own excursions by hire car or helicopter, or stayed in town spending money, while the rest stayed on board.
Among other ships visiting the Bay of Islands will be several new vessels, including the Costa Luminosa, Noordam, Le Soleal and Azamara Quest.
The biggest by passenger numbers will be the Explorer of the Seas and the Voyager of the Seas, each of which carry about 4000 passengers.