In timing with the GreenBuild conference this week in San Francisco, View is also showing off its first pilot installation at the W Hotel (see photos). The window in the W Hotel will be in the lobby, and it will be installed by Monday, if you want to go check it out.

The technology used for View’s windows is called “electrochromic,” where a low-voltage electrical current is applied to the window to change the color of the window to reflect or absorb light. The tinting effect can cool or warm a room, and save energy by cutting down on air conditioning or heating. Mulpuri tells me that View’s windows can save 20 percent of the costs off of a heating and cooling system, 20 percent off of lighting, and can reduce peak load (electricity at peak times of use) by 25 percent.

There’s a few other companies working on electrochromic windows, like Sage Electrochromics which was bought by Saint-Gobain this Spring. The big issue with electrochromic windows, is making the economics work for  the customers. The window systems themselves are obviously a premium product over, say, window blinds, which have a similar shading effect. Mulpuri would only say the windows cost two times over a standard system for residential installations, and potentially 50 percent more for commercial installations.

But when the long term savings are considered, the window systems can pay for themselves over time, and can also be cost effective at the start in an overall system by enabling features, like, say, a smaller heating and cooling system to be installed. The windows also have a high-end design and aesthetic effect, and have novel functions, like being able to be tinted using an iPhone app.

View makes its windows by sputtering an atomic layer, 1 micrometer thick, of the electrochromic material onto a pane of glass. The layer is then sandwiched by another pane of glass. The layer is made of tungsten oxide for its initial product, and View licensed this technology from Lawrence Berkeley National Laboratory.

View has raised about $125 million from DBL Investors, GE, Khosla Ventures, Navitas Capital, Sigma Partners, and The Westly Group. The company has been working on this technology for five years, which shows how much funding and time it takes some of these clean technology startups to scale to commercial production. The window systems are being made in View’s factory in Mississippi.

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Soladigm has been building a $130 million window factory in Mississippi, which was supposed to start shipping windows in the first quarter of 2012. It’s unclear if the company has started shipping its windows yet, but I’ll update this if I hear more from them. I would speculate that this funding will go toward helping the company move into commercial production. Update: A Soladigm spokesperson says the company hasn’t begun commercial production out of the Mississippi plant yet, but is on track to do so later this year.

Founded in 2007 and based in Milpitas, Calif., Soladigm makes electrochromic windows, which change colors to reflect or absorb light when a low-voltage electrical current is applied. The tinting effect can cool or warm a room, and save energy by cutting down on air conditioning. The Department of Energy has noted that electrochromic windows can cut a commercial building’s air conditioning costs by up to 20 percent per year.

The company uses a thin-film deposition process to create conducting layers between two panes of glass for controlling the amount of light and heat that pass through. The secret sauce to the window is the materials used to make the electrochromic layer. Soladigm is using a tungsten oxide-based electrochromic layer for its initial product. Soladigm has licensed technology from Lawrence Berkeley National Laboratory.

The big challenge for popularizing electrochromic windows is cost. Electrochromic windows can fetch around $100 per square foot, while windows with reflective coating already are widely available and cost far less. Soladigm has declined to disclose its manufacturing costs.

Soladigm competitor Sage Electrochromics, was acquired by French glass and construction giant Saint-Gobain earlier this year. Saint-Gobain had long been an investor in Sage.

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SolarBridge raises $25 million, series D: SolarBridge makes solar microinverters, which are miniature versions of conventional central solar inverters that are necessary for converting the direct current generated by solar panels to alternating current for feeding the grid or to be used onsite. Instead of matching a central inverter to a dozen panels at a time, each microinverter serves one panel. This design allows the microinverters to calculate and adjust the optimal energy output of each solar panel and prevents poor-performing panels from affecting the power output of the best-performing ones.

SolarBridge raised $25 million in a series D round led by Shea Ventures and including Battery Ventures, Rho Ventures and Osage University Partners. The company has raised more than $71 million to date, including a $19 million series C round last year. SolarBridge says the funding will be used to launch “new hardware and software products, increase sales and marketing efforts and expand the company’s operations globally.”

Solar microinverters are the future of solar inverters, but are still at an early market phase. Enphase Energy is another leader in the microinverter space and Enphase went public earlier this year.

Redwood Systems raises $11.75 million, series C: Redwood Systems makes a control and sensor system for LEDs that runs over an optimized version of Ethernet cables. The company just closed $11.75 million in a series C round from investors including Battery Ventures, U.S. Venture Partners, Index Ventures and Mitsui & Co, Ltd. Japanese conglomerate Mitsui started backing the company a year ago.

Redwood Systems is four years old and some of its customers include SAP, Volkswagen, Johnson Controls and most recently, Facebook. Commercial building owners and data center operators can use Redwood’s LED system to cut the amount of lighting used throughout the building — in some cases, up to 70 percent over standard non-networked fluorescent lighting systems. LEDs are more efficient than fluorescents, but Redwood’s management system also monitors the building environment, including temperature and room occupancy, and can dim and manage the lights to help maximize efficiency.

Lighting Science Group raises $140 million: LED maker Lighting Science Group has closed on $140 million in private funding, led by private equity firm Riverwood Capital, and including Pegasus Capital Advisors. Lighting Science Group is already publicly traded on the OTC bulletin board, and over a year ago indicated that it wanted to go public on the Nasdaq and raise $150 million.

Lighting Science designs and makes LED lamps and other light fixtures for the residential, commercial and industrial market. The company has been selling LED lighting for nearly a decade and owns factories in Satellite Beach, Florida and Monterrey, Mexico.

GreenBytes raises $12 million, series B: GreenBytes makes data de-duplication storage gear, which are tools that reduce redundant data as well as store data on energy efficient storage solid state drives. The company raised a $12 million series B round from Battery Ventures and Al Gore’s Generation Investment Management.

“Primary storage”, or top tier storage, is comprised of hardware designed for quick data access and are usually reserved for active or just-created data.  Beneath this are “secondary tiers” devoted to backup storage, archives and storage of lower priority business data. GreenBytes’ appliances are deployed close to the top tiers of storage so that fewer data trickles down to other tiers and the greater the potential cost and energy savings overall. Despite the promise of data deduplification, IT managers are still wary about it, according a GigaOM Pro report “De-Duplicating the Storage Industry” (subscription required).

Solar Mosaic raises $2.5 million: According to a filing, the kickstarter of solar, SolarMosaic has raised $2.5 million. The company is just about to launch the truly disruptive part of its business: as early as this Summer SolarMosaic plans to start offering people a way to buy into rooftop solar panel projects, and make back a return on their investment over time.

Soladigm raises close to $5 million in debt, option: Soladigm, which makes electrochromic “smart” windows that tint when electricity is applied to them, has raised $5 million in debt and options according to a filing. The startup was founded in 2007 and is based in Milpitas, Calif.

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Sage at one point was also a recipient of a conditional commitment for a $72 million loan guarantee from the Department of Energy (via the 1703 program), but that loan was never closed, Sage confirms with me. I think the loan probably wouldn’t be able to be finalized now, anyways, to a wholly-owned French company.

That loan guarantee was supposed to help Sage build out a $135 million, 250,000 square foot factory in Faribault, Minnesota, which Sage said back then would be “the world’s largest and most advanced electrochromic glass manufacturing facility.” Now the two companies say in a release this morning that the acquisition deal will enable the factory to finally be finished, with production of the smart windows supposed to start in January of 2013. Saint-Gobain says the factory will produce 3.2 million sq. ft. of smart glass annually, and will create 160 jobs.

Sage makes so-called electrochromic windows, which use low voltage to tint the windows and cut the light that can pass through them from more than 60 percent to less than 5 percent. That leads to both less light, but also less heat being drawn into the building. The DOE has noted that electrochromic windows can cut a commercial building’s air conditioning costs by up to 20 percent per year.

Sage’s windows are made using an all-ceramic stack of thin-film coatings over a glass substrate. The company was founded in 1989 and later received funding from venture investors including Good Energies, Applied Ventures (the VC arm of Applied Materials) and Bekaert.

The problem with smart window technology is that it’s always been too expensive — both to buy and to produce. Soladigm is another electrochromic window maker that raised a lot of money to build a factory in Mississippi, and was supposed to start shipping its windows in the first quarter of 2012.

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US e-Chromic makes an electrochromic thin film that can be applied to the inside of existing windows, but can work in a similar way to the brand new dynamic windows that are being made by these players in their next-gen factories. US e-Chromic says when its film is applied to windows it can reduce cooling costs in buildings by 30 to 40 percent during warm air-conditioning heavy months.

The company, based in Boulder, Colorado, is commercializing tech that was developed at the National Renewable Energy Lab (NREL) in Golden Colorado. So far the startup, which is led by CEO Loren Burnett, has raised a small amount of funding from Amplifier Ventures.

Soladigm, on the other hand, has major manufacturing plans. The company is building a $130 million factory in Mississippi, and says it plans to start shipping its electrochromic windows in the first quarter of 2012; investors include Khosla Ventures, Sigma Partners, DBL Investors, and The Westly Group. Soladigm uses a thin-film deposition process to create conducting layers between two panes of glass that control the amount of light and heat that pass through the window.

Sage also has big production plans. The U.S. Department of Energy offered Sage a loan guarantee of $72 million, and Sage has a 300,000-square-foot factory, in Minnesota.

However, US e-Chromic is still in the R&D stage. The company was founded just in April 2011.

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The idea is that the window lets in less light, while still being transparent, so buildings get needed shade during hot sunny hours, reducing their air conditioning use and making the building more energy-efficient. At the same time, the panels produce solar power, which the building can use for electricity. The company is currently targeting architects and commercial building owners.

Four-year-old Pythagoras Solar will announce its first commercial installation in the coming weeks, CEO Gonen Fink told me in an interview, and the company has been working for several years on smaller pilot projects, like one on the south-facing side of the Willis Tower in Chicago. The company, which has its R&D and investors in Israel, is in the process of moving from the project stage into mass production. The company raised a $10 million series A round from Israel Cleantech Ventures, Pitango Venture Capital and Evergreen Venture Partners.

So when Pythagoras is churning out these solar windows on a grand scale will they fly off the shelves? Part of the success will depend on the math. The solar windows cost more than a standard window, bur will be priced on par with some of the new dynamic tinting windows that are coming to the market from firms like Soladigm and Sage, said Fink.

The windows are also more expensive per square foot than straight solar PV, but factoring in the energy efficiency savings and clean power savings of the solar windows, Fink says their return on investment is 3 to 5 years. Solar panels, on the other hand, take longer, like 7 to 12 years to deliver a return.

The power production of the solar windows isn’t all that high — 13 watts per square foot — so a big chunk of the return seems to be coming from the energy-efficient aspect of the window. So part of the market Pythagoras is competing with is lower-cost but energy-efficient windows like those made by Serious Energy, and super-cheap stuff like blinds.

The cool factor of the windows will be what drives the market for these solar windows initially: eco-minded architects and real estate developers that want an extra green touch. Pythagoras needs some high-profile buildings to showcase its solar windows to get the word out. The GE smart grid challenge was also good for that.

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GE said in January that some of the home-focused startups that entered the challenge could get investment from GE and its VC partners, and some will receive $100,000 in award money. As of January, $55 million of the $200 million fund had been committed, and out of 4,000 ideas submitted, there had been more than 1,100 in the category of home energy, said GE.

Back in November, GE named 12 winners of its smart grid challenge, which split the first $55 million, and five “innovation award winners” that received $100,000 each. The 12 winners included some bigger companies like OPower, Consert, SynapSense, Soladigm, Scientific Conservation, and SustainX, while the innovation winners included smaller companies like Winflex, IceCode, and GridON.

GE has a strong interest in the home energy market. At CES in January, GE showed off its new Home Energy Management business, including its Nucleus home energy device, as well as its Brillion line of smart appliances and smart thermostats. All these are meant to connect within the home to GE’s smart meters, then as a gateway to the smart grid.

At GE’s event on Thursday, it will also feature an 8-hour discussion between tech execs and pundits, which will include speakers like entrepreneur Tim O’Reilly, designer Yves Behar, and inventor Saul Griffith. Behar designed GE’s electric vehicle charger.

We’ll bring you the winners Thursday morning!

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Soladigm plans to use some of the money for its first factory, which will cost about $130 million, be located in Mississippi, and be set to start shipping its electrochromic windows in the first quarter of 2012, the company said.

The startup, founded in 2007 and based in Milpitas, Calif., has attracted a good amount of funding over the past year. Last summer, it announced the plan to build its factory in Mississippi. The state has offered the company a loan of $40 million and another $4 million in other incentives to set up the factory there. Soladigm was awarded a roughly $3.5 million federal research grant and another research grant of $400,000 from the California Energy Commission.

Soladigm raised $30 million for its initial C round last December, and was chosen by General Electric as one of the first 12 winners of a $200 million challenge to encourage greentech development. The funding announcement on Tuesday brings the total venture capital raised by the company since its inception to about $70 million and added the Westly Group and Navitas Capital to its roster of investors.

Electrochromic windows are so called because they change colors to reflect or absorb light when a low-voltage electrical current is applied. The ability makes it possible to cool or warm up a room and thereby save energy costs. Soladigm’s CEO, Rao Mulpuri, explained the company’s technology and plan to me last year and said a study of commercial buildings in five cities showed a 25-percent cut in energy use in heating, ventilation and air conditioning.

The startup uses a thin-film deposition process to create conducting layers between two panes of glass for controlling the amount of light and heat that pass through. The layers are made up of two, transparent, conductive oxide films that sandwich an ion storage layer, an electrolyte and an electrochromic layer. A low voltage applied to the conductive oxide drives the ions out of the storage layer and across the electrolyte to run into the electrochromic layer. The collision causes the electrochromic material to absorb or reflect light, depending on how it’s tuned. It also causes the material to darken and give the glass window that tinted look. The tinting goes away when the voltage is reversed to drive the ions back to its storage layer.

The secret ingredients are the materials used to make the electrochromic layer. Soladigm is using a tungsten oxide-based electrochromic layer for its first-generation product. Tungsten oxide is a well-known material for this type of window, but it also has shortcomings, such as absorbing too much light and causing the windows to become too hot to touch.

Soladigm has licensed technology from Lawrence Berkeley National Laboratory that will use alternative materials to solve the over-heating problem. The company also received two patents last year for using different materials for various layers in between glass (see first patent here and second patent here).

There are different ways to control electrochromic windows. A simple control system will allow people to manually make the switch. Sensors can be added to activate the windows when the room temperature reaches a particular level or during a particular time of the day, for example.

The big challenge for popularizing electrochromic windows is cost. Electrochromic windows can fetch around $100 per square foot, while windows with reflective coating already are widely available and cost far less. Soladigm has declined to disclose its manufacturing cost; it has a pilot production line.

Many other electrochromic window developers also are eyeing what could be a good market. Sage Electrochromics in Minnesota already has been shipping products, and it recently raised $80 million from Saint-Gobain to build a new factory. The U.S. Department of Energy also offered Sage a loan guarantee of $72 million last year. Last October, Sage said it had broken ground on the new, 300,000-square-foot factory, located in Minnesota.

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