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

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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

Minnesota Finds Net Metering Undervalues Rooftop Solar

Utilities should be paying more for their customers’ surplus solar power generation according to a solar pricing scheme approved by Minnesota’s Public Utility Commission last month and expected to be finalized in early April. Minnesota’s move marks the first state-level application of the ‘value of solar’ approach, which sets a price by accounting for rooftop solar power’s net benefits, pioneered by the municipal utility in Austin, TX.

Minnesota is one of 43 U.S. states that requires utilities to pay retail rates for surplus solar power that their customers put on the grid. Utilities across the U.S. are fighting such net metering rules, arguing that they fail to compensate the utility for services that their grid provides to the distributed generator. So last year pro-solar activists and politicians in Minnesota called the utilities’ bluff, passing legislation tasking the state’s Department of Commerce with calculating the true value of rooftop solar power. Continue reading

Life’s a ‘Paternoster’ (and then you fly)

Solon SE’s new paternoster lift. Credit Kevin Matthews / ArchitectureWeek.

“Don’t leave the planet to the stupid.” The corporate tag line from German solar module manufacturer Solon SE screams: ‘We reject complacency’ (not to mention gentility). It’s a slap-in-the-face warning to expect the unexpected, so I was looking for something completely different when I visited Solon’s one-year old Berlin headquarters on an architectural tour of Germany last week. I was not to be disappointed. What I found is probably the first cyclic elevator system installed anywhere in decades.

No pressing a button and waiting for a lift with this modern incarnation of a late-19th-C elevator design! In a cyclic elevator a string of passenger cars run by in a continuous loop. One simply steps into one of the open cars scrolling up or down through its adjacent elevator shafts and takes off. To your weary Canadian correspondent, presently immobilized in Berlin by an angry planet, the hassle-free transport offered by Solon’s cyclic lift was a source of almost drunken pleasure.

Unfortunately, it may also be quite stupid (so to speak). Continue reading

Deciphering Big Oil’s Retreat from Renewables

road_tanker_refuelling_credit-bpA New York Times article this week concludes that major oil and gas companies are, as the headline roared, “Loath to Follow Obama’s Green Lead.” Such stories bashing Big Oil’s slim investment in renewable energy tend to fall short by failing to consider how renewables intersect with an oil major’s core business, and this one is no exception.

As the Times ably demonstrates, big oil is freezing or cutting investment in renewable energy and doing so from a relatively small base. It notes that Shell, which has frozen spending on wind, solar and hydrogen energy, has invested just $1.7 billion on alternative energy projects since 2004 compared to $87 billion to keep its oil and gas flowing.

That should come as little surprise since Big Oil’s insubstantial and fickle commitment to renewable energy goes back decades. Following the 1973 oil shock, for example, U.S. oil majors of the time such as Mobil and Chevron embraced photovoltaics, only to dump the projects when oil prices crashed and OPEC’s power waned a decade later. British Petroleum’s promise to go “Beyond Petroleum” already looked weak five years ago when it ditched production of next-generation cadmium-telluride thin-film photovoltaics — the technology that Tempe, AZ-based First Solar has since ridden to the top of the world PV market.

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Toyota’s Underwhelming Solar Prius

2010-prius-credit-toyotaThe solar roof that Toyota is offering as an option on its next-gen Prius hybrid sedean is even less efficaceous than expected, according to specialty publication EVWorld. The solar panels, reports EVWorld, will add not a nanowatt of charge to drive the Prius.

Technology Review looked at the potential impact of a solar roof on the Prius last summer when rumors of Toyota’s plans first emerged. The clear conclusion of the experts: Keep solar panels on rooftops, where they can be tilted towards the sun for maximum efficiency and multiplied to provide the kilowatts of power it takes to drive a car. A solar rooftop would be just a “marketing gimmick” said Andrew Frank, a plug-in hybrid pioneer at the University of California, Davis, and chief technology officer for UC-Davis hybrid-vehicle spinoff Efficient Drivetrains.

Toyota, it turns out, won’t even bother plugging its solar rooftop panel into the 2010 Prius’ nickel-metal hydride battery.

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