Advance Solar Deployment
Solar photovoltaic (PV) distributed generation is becoming more accessible and increasingly more affordable for a growing number of families and businesses. Concern for our environment is also driving more and more interest in solar PV installations. Once the energy efficiency measures are completed in homes and commercial buildings, investments are being made in self-generation.
Wisconsin is among America’s electric cooperatives that are planning solar installations that will provide more than 150 MW of new solar capacity by 2020 at 199 rural electric co-ops in 27 states and American Samoa. In fact, electric co-ops were among those featured by President Obama in a May 9 announcement at a Walmart in Mountain View, California, regarding executive actions to advance solar deployment and energy efficiency.
Through public–private partnerships, electric co-ops have been implementing and studying distributed generation deployment. Cooperative Research Network (CRN) our research arm is partnering with the Department of Energy on research to bring down the price of solar and make utility-scale solar projects accessible to the not-for-profit co-ops. In addition, early deployments of solar PV in states with constrained fuel resources provides real time data on integrating renewable energy into the grid. An example is the electric cooperative on the beautiful Hawaiian island of Kaua’i. While it feels far removed from many of the problems of today’s world, when it comes to distributed generation, the island provides a glimpse into a more complicated future.
On Kaua’i there is no national power grid, just the island’s small, self-contained grid. Diesel fuel for generation has to be shipped in across the Pacific. That makes energy costs high and means Kaua’i has a lot of people with solar panels on their roof.
As a result, Kaua’i Island Utility Cooperative (KIUC), the local power supplier and distributor, deals with a higher percentage of renewable distributed generation than any other electric co-op in the nation. Roughly 2,000 members have photovoltaic (solar) arrays that can send power back into the co-op’s self-contained grid, amounting to about 20 percent of the co-op’s daytime electrical load.
“It’s a technical challenge,” says Mike Yamane, KIUC chief of operations. To provide high-quality reliable power, electrical utilities control the frequency and voltage of the current moving down their lines. But as more distributed generation comes on line, says Yamane, this process becomes more difficult. “Photovoltaic systems aren’t really meant to regulate frequency or voltage,” he explains.
As the amount of distributed generation on a line rises, another potential danger is called “islanding.” This can occur when an outage brings down the local grid, but a line continues to be live because power keeps feeding in from distributed generation. Islanding can be a safety hazard for linemen working to get the power back on and can cause problems when the grid does power back up.
These and other aspects of distributed, renewable generation can impact a power system’s overall stability if the right measures aren’t taken. KIUC, for example, has operating parameters its members must follow with their power inverters, which convert direct current from a solar cell into alternating current used on the grid, and with the relays that connect solar panels to the network.
If you are planning a solar PV installation remember to check with your electric cooperative about integration and operation with system requirements.