Solar energy has always had one big problem: It can only be used during the day, when the sun is shining. This obstacle has inspired companies to build a solution.
This issue has affected Hawaii greatly. Over 20 percent of the state's energy comes from renewable resources, including solar, according to the Wall Street Journal. On the island of Oahu, 13 percent of residents have installed solar panels, the highest percentage in the U.S. In 2014, Hawaii used 168 watts of solar energy per capita, 121 more than Arizona, the second highest.
Hawaii's unique energy use
The number of solar panels aren't the only ways Hawaii's energy generation is different than those of other states. Unlike the continental United States, which has three electric grids shared between 48 states, Hawaii has one electric grid per island. The smaller the grid, the more unstable it is, the Wall Street Journal reported.
Oil produces the majority of Hawaii's energy; other states have decreased their dependence on oil dramatically. The state's continued reliance on oil has brought Hawaii's energy costs to 33.26 cents per kilowatt hour in 2013 - more than twice as much as Alaska, the next most expensive state.
The cost of energy is one of the reasons Hawaiians have been so receptive to solar technology. However, the amount of solar panels installed has brought a new set of problems. On sunny days, the solar panels generate more electricity than is needed. When a home produces energy, the excess gets pushed back into the grid. When more than 50,000 homes start sending energy into an overwhelmed grid, equipment in power substations can be damaged.
There are a couple solutions to this issue. The first is the use of smart inverters. These will help to convert energy into forms that can be used in homes or sent over electric lines. Future inverters may allow people to manually regulate how much power they send over lines, which will decrease risk to equipment.
Another solution is one that will also address the limited time period solar energy is available. Energy storage systems would allow residents to use solar-generated power long after the sun sets.
This solution is making big strides lately. This month, Kaua'i Island Utility Cooperative signed a 20-year contract with SolarCity, which would bring new storage technology to the island of Kaua'i, according to a press release from SolarCity.
The agreement will place a 52-megawatt hour battery system next to KIUC's Kapaia power plant. The battery system will feed up to 13 megawatts into the grid and store the rest to be used at night. This will be the first time dispatchable solar energy will be available in the U.S.
This will reduce the need for oil-generated electricity, Jon Yoshimura, SolarCity's Director of Policy and Electricity Markets, explained in the press release.
"SolarCity is excited to bring the first dispatchable solar storage system to the island of Kaua'i," Yoshimura said. "Hawai'i has been and continues to be at the forefront of new technology and research for solar and storage. This solution will allow for more efficient load balancing and will reduce dependence on fossil fuel-based power."