Two years ago, an article made the rounds on the internet claiming that there is an “upper limit” to the penetrations of wind and solar any grid can reach. The author, Jesse Jenkins, claimed that once either of these resources reached a penetration level that roughly corresponded with their capacity factors, that it was “increasingly difficult” and impractical to deploy more.
Jenkins, meet Kaua’i. This year the island’s utility expects to get 43% of its power from renewable energy resources, with solar alone providing 22.8% of the utility’s sales. This is despite far more difficult conditions for the deployment of renewable energy than on most grids. Among the challenges for Kaua’i is that as it has no electrical interconnection with other islands, it cannot balance fluctuations in supply and demand by importing and exporting power.
But Kaua’i is not stopping there. Today SunPower announced that it has been chosen by AES Distributed Energy to supply its modular Oasis power blocks for the largest solar and battery storage project not only in Kaua’i to date, but in Hawaii. The 28 MW PV plant will be accompanied by 20 MW of batteries, each with a five-hour duration, for a 100 megawatt-hour rating.
As part of the Oasis package SunPower will supply its high-efficiency E-Series PV modules based on its back-contact technology, mounted on single-axis trackers. AES Distributed Energy will own the project, which is expected to be operational by the end of 2018.
When other solar projects either under construction or being planned are completed, including customer-site rooftop PV, solar could meet more than 40% of Kauai’s electric demand – well more than solar’s capacity factor even in desert climates. This puts Kaua’i Island Utility Cooperative (KIUC) on a solid path for renewables to exceed 70% of its power by 2025, well ahead of its 2030 goal.
The integration of energy storage is not accidental on these projects. As an island with a tourist economy, Kaua’i’s peak electricity demand comes after the sun goes down, and due to endangered bird species no wind turbines can be built on the island. This means that overnight wind output cannot balance daytime solar generation, as is the case in Germany.
And in addition to battery systems, Kaua’i is also deploying pumped hydro storage. In September KIUC approved a land lease agreements and expenditures for permitting and surveying for a 25 MW pumped hydro project on the island’s west side.