4 Factors Driving the Marriage of Solar and Energy Storage

A solar-powered microgrid demonstrates the potential of coupling big batteries with commercial solar. What if you could finance the energy storage equipment, much the way solar panels are financed, and the batteries provided a revenue stream? Modern grid-scale battery systems are only put in place to save money or provide services to the grid. An example is one installation that includes 402 kilowatts’ worth of solar canopies in the parking lot and, in a twist that differentiates it from most commercial solar projects, a shipping-container-sized battery from startup Solar Grid Storage. Here in Knoxville we have a battery enhanced solar powered car-charging station located at the EPRI location off Dutchtown Road. On a daily basis, though, the battery will deliver frequency regulation services to the local wholesale grid. By providing quick bursts of power to keep a steady balance between supply and demand, battery owner Solar Grid Storage will earn money that is normally paid to natural gas power plant operators.

Here are the factors that are driving the combination of commercial solar and energy storage.

1. The technology is there. Better batteries are in development that will lower cost.

2. The economics can make sense. AES Energy Storage, for instance, provides frequency regulation services at a wind farm in West Virginia, buffered by a 32-megawatt lithium-ion battery bank. Revenue comes from reducing demand charges by using stored energy during peak hours. Most of its customers are in California, which has subsidies for distributed energy storage. By contrast, the desire to have emergency power has become a priority in East Coast states hit hard by Hurricane Sandy and other severe storms.

3. Solar installers want storage — if it pencils out. Military bases and island locations that rely on diesel generators are obvious candidates. A battery can smooth out the flow of power that panels provide to the local grid and address issues, such as the drops in voltage that come when clouds pass over. Batteries could also enable solar installations in places, such as farms, which would have required costly upgrades to the grid infrastructure. The contracts to finance a combined solar and storage system are complex and need to become more standardized, as power purchase agreements are, said president Scott Wiater of Standard Solar. Financing these types of systems is still relatively new and developers need to find customers willing to try not only solar, but also relatively new energy storage technology.

4. NRG Energy Inc. and Exelon Corp.’s Constellation unit say interest in combining solar power with battery storage has soared in the year since Hurricane Sandy knocked out power to millions of homes and businesses on the East Coast. They are among more than a dozen solar providers that have introduced or enhanced in the past year systems that combine rooftop solar panels that generate power and batteries that retain electricity to use later.
People with solar-powered homes and businesses were frustrated to discover that losing power from local utilities also knocked out the inverters that connect rooftop panels to the grid, leaving them unable to tap the electricity they were producing. Adding battery storage solves that problem, said Tom Doyle, chief executive officer of NRG’s solar unit.

It’s also a growing threat to utilities.
“When Sandy came along we really didn’t have a product to keep solar power flowing during blackouts,” Doyle said in an interview yesterday at the Solar Power International conference in Chicago. “Now we can install systems that continue operating when the grid fails, and the costs are coming down.”
Battery storage can add more than 20 percent to the cost of a typical 10-kilowatt solar system for a four-bedroom home, Brendon Quinlivan, director of solar development at Constellation, said in an interview.

original article can be found at: http://www.greentechmedia.com/articles/read/three-factors-driving-the-marriage-of-solar-and-energy-storage and http://www.bloomberg.com/news/2013-10-23/nrg-and-exelon-see-batteries-spurring-demand-for-solar.html

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