Storing Solar Energy: A great idea caught on contested ground

Adding energy storage to sites with rooftop solar power generation offers a range of potential benefits. A battery can help smooth out solar’s inherently variable supply of power to the local grid, and even keep buildings powered during blackouts. Consequently, power-conversion innovators are developing a host of new products designed to reduce the cost and improve the efficiency of integrated solar-storage systems.

Some analysts project a boom in the co-location of solar and energy storage. GTM Research, for example, foresees that co-located PV and storage will grow from $42 million in 2014 to more than $1 billion by 2018. However, the market is moving slower than it might thanks to a little-discussed regulatory roadblock in the United States.

According to Vic Shao, CEO for the Santa Clara, California-based energy storage startup Green Charge Networks, tightly integrating storage with photovoltaics in some key states—including Hawaii and California—runs afoul of the “net metering” rules by which PV owners earn lucrative retail rates for the surplus power they feed to the grid. Adding storage can disqualify solar systems for net metering, in which utilities can pay their owners wholesale power rates that are several times lower than retail. “That is obviously a pretty big problem for anybody considering solar. That could kill a lot of projects,” says Shao. Continue reading

Solar Power and Grid Stability: Scenarios and solutions

hawaii.gridx299Renewable energy is often intermittent, and that variability presents a variety of challenges to power grids. The nature and magnitude of the challenges depends on the time frame — from fractions of a second to seasonal or even multiyear variations — as well as the nature of the grid itself. The latter is evident in two of my articles from last week looking at how seconds-to-minutes fluctuations in solar power complicate grid controllers’ efforts to maintain alternating current at the 60 hertz frequency and the roughly 110 volt power levels required by North American devices.

Fluctuating AC frequency stars in my Technology Review dispatch from the paradise of Kauai, where the island utility is riding an electrical roller coaster as it pushes solar towards 80 percent of peak power flows Continue reading

Beacon Power Hits a Speed-bump, but it’s No Solyndra

Flywheel energy storage developer Beacon Power filed for bankruptcy last weekend, prompting immediate comparisons to infamously failed solar manufacturer Solyndra. But while both firms used millions of dollars in federal loan guarantees to expand their businesses, Beacon Power — which Spectrum profiled this summer — has working assets and a good shot at restructuring and carrying on. Continue reading