SolarCity has chosen the battery company for a landmark utility-scale solar plus storage project on the Hawaiian island of Kauai, and the supplier is hardly a surprise: Tesla Energy. Tesla will supply a 52 megawatt-hour (MWh) Powerpack lithium-ion battery storage system to accompany SolarCity’s 13 MW solar PV project.
The Powerpack is Teslas product for commercial and utility-scale installations, and uses a modular design adapted from the technology used in Teslas electric cars.
Tesla Energy is part of Tesla Motors. SolarCity Chairman Elon Musk founded and serves as CEO of Tesla Motors, and his cousins founded and and serve as executives at SolarCity. So while a press release by Kauai Island Utility Cooperative (KIUC) states that the company conducted a comprehensive competitive solicitation, SolarCity ultimately chose to procure batteries from a company to which it has very close ties.
The project on Kauai could serve as an excellent showcase for Musks various enterprises. Unlike existing utility-scale solar and storage systems on Kauai where batteries are used to smooth solar output and supply steady power during the day, the SolarCity system will be used to meet peak demand on the Kauai grid, which comes after the sun sets from 5 PM to 10 PM.
The 20-year power contract for the project states that SolarCity will supply electricity for US$0.145 per kilowatt-hour, a price which demonstrates the increasing competitiveness of utility-scale solar PV and battery storage.
Kauai currently meets 17.5% of electric demand with solar PV. This is roughly twice the portion that Italy gets, as the leading nation for integration of high levels of solar. SolarCity expects to complete its solar and storage project by the end of 2016, and by 2018 KIUC expects to be meeting 25% of demand with solar PV.
For more detail on how Kauai is integrating high levels of solar PV, please see pv magazines interview with KIUC Spokesperson Jim Kelley.