This paper describes a solar + storage methodology that was developed by Clean Power Research® that could be used to value solar energy coupled with battery storage. The paper was developed on behalf of the Interstate Renewable Energy Council, Inc. (IREC), and focused on Hawaii as an example, as it is likely to be an early adopter of storage regulations.
The desire to investigate storage and consider its use as an enabling technology in the islands was motivated by two observations:
The very high level of solar adoption in Hawaii has led to utility concerns that distribution transient over-voltages may exceed allowable limits, and that backfeed on feeders may disrupt circuit protection. This concern led to a backlog in interconnection approvals and a severe disruption in the solar industry. Storage could alleviate this concern by using batteries to reduce or eliminate energy export onto the grid, and relieve reverse power flow concerns.
The generation capacity-related benefits of solar alone, as a non-dispatchable resource, are expected to be modest since the peak demand in Hawaii is found in the evening hours. Storage could be used to charge daytime solar energy for later dispatch during the peak after sundown. Thus, the combination of solar plus storage would increase both capacity and energy benefits.
An evaluation of the economic impact of solar + storage in Hawaii is presented, based on the described methodology.