Sonnen Ships Its 10,000th Battery, Putting Pressure on Tesla and Utilities

“Our goal is really to create a world where everyone is able to cover their own energy needs with a decentralized energy source.”

By: Julia Pyper

German startup Sonnen shipped its 10,000th battery system this week, claiming a leading position in the global smart energy storage market as it takes on Tesla and shakes up the traditional electricity business model.

Sonnen marked the milestone by gifting German homeowner Stefan Wolpert an extra 2 kilowatts of battery capacity and a free membership to sonnenCommunity — Sonnen’s decentralized energy trading platform.

The shipment announcement comes on the heels of the startup’s expansion into the U.S. last month, with a new headquarters unveiled in Los Angeles and a rapidly growing distribution network. Sonnen has already partnered with 30 local solar installers and aims to reach 100 partners by the end of the year.

In early February, Sonnen announced that it is now ready to install systems in Hawaii after meeting the advanced energy storage requirements from the Hawaii Electric Companies (HECO). The sonnenBatterie, which comes fully equipped with smart energy management technology, is billed as an “out-of-the-box” solution that meets the obligations under HECO’s new distributed energy tariffs. Company executives say a 4-kilowatt-hour sonnenBatterie in Hawaii will cost about $10,000 and provide a return on investment in as little as 6.5 years.

At the outset, Sonnen is targeting sales to solar customers in places with high electricity costs, like Hawaii and Puerto Rico. California is another promising market, where storage benefits from incentives and can help solar customers arbitrage time-of-use rates. But the company ultimately sees batteries offering financial and resiliency benefits across the U.S., and is currently working with Spruce to offer attractive financing packages for energy storage in all 50 states.

Sonnen already has 1,000 battery storage systems under contract in the U.S. and aims to contract for up to 3,500 systems through the year. As Sonnen increases its U.S. presence, it continues to grow sales in seven European countries, Australia and the Philippines.

“Our goal is really to create a world where everyone is able to cover their own energy needs with a decentralized energy source,” said Boris von Bormann, CEO of Sonnen North America, at the company’s L.A. office launch. “Of course we love the utilities, but just imagine if you could take your energy future into your own hands.”

Tesla vs. Sonnen

Sonnen is not the only company seeking to empower customers through energy storage, however Read more »

Enormous Blades Could Lead to More Offshore Energy in US

Todd Griffith shows a cross-section of a 50-meter blade, which is part of the pathway to the 200-meter exascale turbines being planned under a DOE ARPA-E-funded program. The huge turbines could be the basis for 50-megawatt offshore wind energy installations in the years ahead. Credit: Photo by Randy Montoya

A new design for gigantic blades longer than two football fields could help bring offshore 50-megawatt (MW) wind turbines to the United States and the world.

Sandia National Laboratories’ research on the extreme-scale Segmented Ultralight Morphing Rotor (SUMR) is funded by the Department of Energy’s (DOE) Advanced Research Projects Agency-Energy program. The challenge: Design a low-cost offshore 50-MW turbine requiring a rotor blade more than 650 feet (200 meters) long, two and a half times longer than any existing wind blade.

The team is led by the University of Virginia and includes Sandia and researchers from the University of Illinois, the University of Colorado, the Colorado School of Mines and the National Renewable Energy Laboratory. Corporate advisory partners include Dominion Resources, General Electric Co., Siemens AG and Vestas Wind Systems.

“Exascale turbines take advantage of economies of scale,” said Todd Griffith, lead blade designer on the project and technical lead for Sandia’s Offshore Wind Energy Program.

Sandia’s previous work on 13-MW systems uses 100-meter blades (328 feet) on which the initial SUMR designs are based. While a 50-MW horizontal wind turbine is well beyond the size of any current design, studies show that load alignment can dramatically reduce peak stresses and fatigue on the rotor blades. This reduces costs and allows construction of blades big enough for a 50-MW system.

Most current U.S. wind turbines produce power in the 1- to 2-MW range, with blades about 165 feet (50 meters) long, while the largest commercially available turbine is rated at 8 MW with blades 262 feet (80 meters) long.

“The U.S. has great offshore wind energy potential, but offshore installations are expensive, so larger turbines are needed to capture that energy at an affordable cost,” Griffith said.

Barriers remain before designers can scale up to a 50-MW turbine — more than six times the power output of the largest current turbines.

“Conventional upwind blades are expensive to manufacture, deploy and maintain beyond 10-15 MW. They must be stiff, to avoid fatigue and eliminate the risk of tower strikes in strong gusts. Those stiff blades are heavy, and their mass, which is directly related to cost, becomes even more problematic at the extreme scale due to gravity loads and other changes,” Griffith said.

He said the new blades could be more easily and cost-effectively manufactured in segments, avoiding the unprecedented-scale equipment needed for transport and assembly of blades built as single units.

The exascale turbines would be sited downwind, unlike conventional turbines that are configured with the rotor blades upwind of the tower.

SUMR’s load-alignment is bio-inspired by the way palm trees move in storms. The lightweight, segmented trunk approximates a series of cylindrical shells that bend in the wind while retaining segment stiffness. This alignment radically reduces the mass required for blade stiffening by reducing the forces on the blades using the palm-tree inspired load-alignment approach.

Segmented turbine blades have a significant advantage in parts of the world at risk for severe storms, such as hurricanes, where offshore turbines must withstand tremendous wind speeds over 200 mph. The blades align themselves to reduce cantilever forces on the blade through a trunnion hinge near the hub that responds to changes in wind speed.

“At dangerous wind speeds, the blades are stowed and aligned with the wind direction, reducing the risk of damage. At lower wind speeds, the blades spread out more to maximize energy production.” Griffith said.

Moving toward exascale turbines could be an important way to meet DOE’s goal of providing 20 percent of the nation’s energy from wind by 2030, as detailed in its recent Wind Vision Report.


Solar PV Provides 7.8 Percent of Italy’s Electricity in 2015

By: Ilias Tsagas

Credit: Shutterstock.

Solar PV systems in Italy in 2015 generated 24,676 GWh of electricity, covering 7.8 percent of the country’s electricity mix, according to Terna, Italy’s electricity transmission grid operator. That total is significantly higher than the previous year, when PV systems in Italy had generated 21,838 GWh of electricity or 7 percent of Italy’s electricity mix. So, in clear GWh numbers, Italy’s electricity generation from PV in 2015 increased by 13 percent compared to 2014.

Terna’s 2015 statistical data are preliminary, meaning that the numbers will be revised later however, without reversing the trends.

Of all months in 2015, July was the most productive for Italy’s PV facilities that generated 3,182 GWh. On the contrary, PV generated only 900 GWh of electricity in December 2015.

Overall, based on Terna’s report, Italy covered 28.5 percent of its electricity needs from hydro (44,751 GWh), solar PV (24,676 GWh), wind (14,589 GWh) and geothermal power (5,816 GWh).

Net Metering Drives Italy’s PV Installations 

There is no official data published regarding Italy’s net-metering installations. Since feed-in tariff payments for all new PV plants ended in July 2013, net metering is currently the only remuneration policy scheme driving new installations in Italy, and it is considered to be highly successful.

Furthermore, in August 2014, the Law Decree 91/2014 increased the upper limit for net-metering systems from 200 kW to 500 kW per installation, thus providing the scheme a further boost. It is expected that Italy has installed about 4 GW of net-metering PV systems, while according to some industrial sources net metering in Italy in 2015 added a figure between 400 MW, the lower estimate, to a more optimistic 800 MW of new PV installations.

Alessandro Rubino, a lecturer of economics at the University of Bari, told Renewable Energy World that the scheme is driven by Italy’s electricity prices, which are among the highest in Europe. “However, since January 2015 there are a number of system costs that are likely to reduce the penetration of this scheme.”

A spokesperson for Italy’s renewable energy organization ANIE Rinnovabili told Renewable Energy World that there is strong interest among Italian households and businesses in installing energy storage systems too. However, the spokesperson said, in the absence of governmental legislation regarding the storage of electricity and given the current costs of storage systems, “net metering (the so-called Scambio Sul Posto) is far the most-used tool for the virtual storage of electricity.”


SolarWorld’s Bifacial Modules and Home Storage Solution One Step Closer to Market

The German firm’s Sunmodule Bisun glass-glass module, which uses bifacial cells based on PERC technology, to be presented at forthcoming exhibition in Frankfurt; modular SunPac LiOn battery also to be unveiled.

By:  Ian Clover

The SolarWorld Sunmodule Bisun can, according to the company, increase energy yield by as much as 25%. SolarWorld

First revealed at last year’s Intersolar Europe exhibition in Munich in June, SolarWorld’s new bifacial modules and flexible lithium-ion home storage batteries are set to be unveiled to the market at next month’s Light + Building show in Frankfurt.

The German solar company has hinted at further innovation in both the module field and storage sector for many months, and it appears that the firm’s latest products for both sectors are one step closer to market.

Its Sunmodule Bisun module is a glass-glass module that comprises 60 bifacial cells based on PERC technology. According to SolarWorld, this ensures a 25% increase in energy yield, plus a longer lifespan and added durability is attained because the cells are embedded into the glass and thus protected against external environmental and mechanical influences.

Able to utilize incident light on both the front and rear, this double-sided module thus absords a higher portion of sunlight, and is particularly suitable for flat roofs and ground-mounted systems where more light is reflected from surrounding surfaces. With higher yield and a longer life, SolarWorld believes that the power generation costs per kWh are significantly lower than standard modules in the field.

Modular storage
The expected growth of the German home storage sector this year has shaped SolarWorld’s efforts to remain a key concern for residential solar customers, and its  SunPac LiOn storage system has been designed to meet the needs of such consumers.

Starting with a  storage capacity of 2 kWh, the battery can be scaled up to 10 kWh in increments of 2 kWh, meaning it can expand or contract to mirror the energy storage needs of an average home. SolarWorld adds that the lithium-ion cells ensure 10,000 complete charge and discharge cycles, which would equate to around 20 year of service life for most households.

The system is connected on the AC side, so is easily retrofittable to existing solar systems and inverters, and has a charge controller that automatically recognizes the number of battery modules connected and the scale of power required.

Both components are set to be unveiled at the Light + Building show in Frankfurt, 13-18 March.


Concentrating Dawn-to-Dusk Solar Energy

A donkey grazes in a pasture near solar panels at Sanctuary Dairy Farm Ice Cream in Sunapee, New Hampshire. Photo: Denis Paiste/Materials Processing Center

MOSAIC award spurs MIT research into concentrator solar cells that can run in shade and full sun with power control and wavelength separation.

By: Denis Paiste

Lighter, more efficient flat-plate solar cells are the goal of MIT researchers who kicked off a collaborative research effort Dec. 15 with a three-year, $3.5 million award under the Department of Energy’s ARPA-E program. Their aim is to bring the technology to the marketplace.

“We are early on looking for companies to collaborate with us who are interested in finding a way to bring that technology into the marketplace after the three-year project funding,” says principal investigator Jurgen Michel, senior research scientist at the MIT Microphotonics Center and senior lecturer in the Department of Materials Science and Engineering. “The best outcome is a solar cell and companies that will actually make those or take that into further development to make a product.”

ARPA-E’s Micro-Scale Optimized Solar-Cell Arrays with Integrated Concentration (MOSAIC) program has challenging specifications, Michel says. The goal is to reach overall efficiency of greater than 30 percent, which is about 5 percentage points higher than the best efficiency achieved with crystalline silicon solar cells.

Technical challenges

The MIT-led project, “Integrated Micro-Optical Concentrator Photovoltaics with Lateral Multijunction Cells,” aims to develop a three-junction concentrator cell in a flat-plate system just under 1 inch thick. It includes a partnership with Arizona State University. Besides Michel, collaborators include:

Juejun (JJ) Hu, the Merton C. Flemings Assistant Professor in Materials Science and Engineering, who will design and prototype a special microlens to split sunlight into wavelengths from visible to near infrared and concentrate sunlight up to 300 times;

Eugene A. Fitzgerald, the Merton C. Flemings-SMA Professor of Materials Science and Engineering, who will work on solar cells made from indium gallium arsenide;

David J. Perreault, professor of electrical engineering and associate department head, who will work on power management of the solar cells; and

Cun-Zheng Ning, professor of electrical engineering at Arizona State University, who will work on nanopillar semiconductor material with a bandgap gradient that is grown in a single step.

Ning developed a single-growth process for varying the bandgap in nanopillars by varying the temperature in the reactor. “That would be very low cost, but the challenge there is efficiency. For our approach, we have to get our substrate to low enough threading dislocation densities in order to get low-cost, high-efficiency solar cells,” Michel says.

Multiple benefits

The proposed solar system with a mix of cells to maximize collection of light a varying times of day addresses one of the key issues with solar energy, which is its intermittent nature. As more solar systems are deployed, they will have to be integrated with energy storage systems to achieve maximum benefit, according to The MIT Energy Initiative report, “The Future of Solar Energy,” released in May 2015. Without storage, solar systems can provide power only during the day.

Solar has enormous potential over the long-term. According the MITEI report, installing solar on less than one-half of 1 percent of the continental United States could produce all the electricity the country needs today. Solar also can reduce the nation’s carbon dioxide emissions, the report noted.

FOCUS results

Michel previously received a one-year ARPA-E FOCUS grant for research on Spectrum Splitting for High-Efficiency Photovoltaic and Solar Thermal Energy Generation. Two papers are pending publication on that work, including significant reductions in threading dislocations in solar cells and enhanced performance of indium gallium phosphide (InGaP) solar cells. These indium gallium phosphide materials are called III-V materials because their elements come from columns III and V of the periodic table.

“One of our main goals was to lower the cost of III-V semiconductor solar cells, so we’ve been using a silicon wafer with a germanium-on-silicon virtual substrate to grow our III-V cells on top of that,” Michel explains. “We’ve reduced the threading dislocation density to below mid-106 per square centimeter. Once you get down to about 106 per cm2 in threading dislocation density, you get actually high quality III-V semiconductor materials for high performance solar cells on a silicon substrate and that reduces the cost dramatically.” This technology is available for licensing through the MIT Technology Licensing Office.

In the new MOSAIC work, researchers will include the indium gallium phosphide (InGaP) solar cells based on the germanium-on-silicon approach in the FOCUS program and add solar cells made from gallium arsenide (GaAs) and indium gallium arsenide (InGaAs) to cover the whole spectrum of sunlight. These cells will be connected to each other in a parallel layout. The lens will direct specific wavelengths of light to matching solar cells.

The work builds on an earlier theoretical paper that showed that under realistic operating conditions over the course of a year, parallel cells coupled with wavelength separation, or spectrum splitting, outperformed a stacked array, or tandem, solar cell. “We found that if you split your spectrum in the way you spread it out onto separate solar cells, you have an overall gain in power output compared to the other solar cell,” Michel explains.

In the new project design, Michel says, “We can optimize the power point for each of the cells individually, because we have now CMOS control. That means we can respond very quickly to shading, for instance, [as] a cloud moves across a panel.” Under cloudy skies, light absorbed by silicon cells in the structure will maintain power output at about 20 percent power efficiency.

Despite the three-year prototype goal, it probably will take three to five years beyond that to bring to market a solar cell system that will last for 30 years. “If that can be done, then you’d actually have solar cells that would have a much higher output than current solar cells for thin plates, which makes it much easier to handle,” Michel explains. “Also if you have to, for instance, track your cells with the sun, weight is much lower, efficiency is high, and so that could be the next step in solar cell efficiency. We are not the only ones that are working on that. There are quite a few competitors. We just hope that one will be successful at least,” he says. “The best outcome is a solar cell and companies that will actually make those or take that into further development to make a product.”