It’s a particularly important trend for solar maker startups that need a premium product to sell. For example, on Monday morning, venture-backed solar startup Alta Devices announced that it’s reached 30.8 percent efficiency for solar cells that it’s marketing to mobile gadget makers. For comparison’s sake traditional silicon solar cells are closer to 20 percent efficient.

Alta Devices says it has been working with mobile device maker customers that want to extend the battery life of gadgets using embedded Alta solar cells. The six-year-old company — which has raised $120 million from investors like Kleiner Perkins, NEA and Dow Chemical — has been planning on making a fast-charging solar iPad cover by the end of the year that could end the need to plug an iPad into the wall or laptop to charge.

Alta Devices says the 30.8 percent is a world record for its dual junction solar cell made from the materials gallium-arsenide, and previously the company was saying its cells were 28 percent efficient. Check out this article for more details on Alta Device’s solar cell technology and a tour of its pilot factory. Alta says it has been shooting for an eventual efficiency of 38 percent for its cells.

Remember this type of efficiency demonstrates what a company might be able to achieve. But whether a company will ever do so will depend on factors such as how much does it scale up its manufacturing, how much money is it able to raise and how efficiently it is operating factory equipment.

Alta’s solar cells are more expensive than traditional silicon cells, but the company is hoping that niche markets like gadget makers will be willing to pay a premium for the next-gen cells. Alta is also developing solar cells for military applications, which can enable troops and their devices to charge up off-the-grid in combat less frequently.

Startups aren’t the only ones that are focused heavily on solar cell efficiency. First Solar last week announced a world record of 18.7 percent for cells made from the material cadmium-telluride. That’s up from the 17.3 percent cell it touted in July 2011.

SunPower has long touted highly efficient solar cells. And suppliers like DuPont sell materials that big solar companies can use to boost the efficiency of their cells.

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But that doesn’t mean there aren’t bright spots on the horizon, and major opportunities for certain kinds of solar startups in 2013. Here’s our list of 13 solar startups to watch in 2013 — some may be under the radar, but all have managed to do one of the following recently: raise money, build factories, launch innovative products and services or otherwise make progress despite the hard times (or because of it).

1). Solar Mosaic: The company brings solar power investments to the masses with its recently launched public online site. Residents of California and New York (as well as accredited investors) can invest in any of the projects for as little as $25 and get what should be a steady, long-term return (of 4.5 percent for the first projects). The company sold out three projects less than 24 hours after the launch this week.

2). Alta Devices: Portable solar chargers could cut the number of batteries a soldier must carry onto the battle field and provide an alternative source of power for drones. Alta Devices is focusing on the military first with its highly efficient solar cells and hopes to use these contracts to scale up manufacturing, slash costs and eventually enter the more conventional solar market where much cheaper solar cells now dominate.

3). Clean Power Finance: The company raises funds to offer power purchase agreements or leases for solar panel installers to market and sell them to homeowners. The company also launched an energy credit trading service and assembled a database of local permitting rules in 2012 so that retail service providers could spend less time and money for figuring out the paperwork they need to do.

4). GlassPoint Solar: With its novel greenhouse design for its solar thermal energy equipment, GlassPoint Solar is targeting the oil industry with its solar steam production, which pries loose oil from wells for easier extraction. Oil companies are warming up to using solar energy to produce steam rather than natural gas, which remains expensive in regions such as the Middle East.

5). QBotix: The company uses robots that move along a tracking system and tilt solar panels during the day to follow the sun. GPS and wireless technology are used to detect problems and monitor the systems.

6). Genability: How do you show customers the amount of energy savings they could achieve or money they could make by going solar? You need accurate data on utility rates, and that’s what Genability specializes in. The startup collects and crunches electric rates — which change often — from utilities across the country. SunPower, SolarCity and SunEdison are customers.

7). Semprius: The prices of silicon solar cells have tumbled in recent years thanks to mega factories by manufacturers mostly in China. To compete, solar cell manufacturing startups must develop something much more efficient that can find other uses as well. Semprius, like Alta Devices, is achieving this by using gallium-arsenide for its cells, but it also is making the solar panels for housing them. The company raised $7.5 million and opened a small factory in North Carolina last year and is targeting the military as well.

8). Stion: After Solyndra’s bankruptcy in 2011, few venture capitalists wanted to invest in using copper, indium, gallium and selenium (CIGS) to make ultra-thin solar panels (that’s the same material Solyndra was working with). Many CIGS startups went out of business or got scooped up in firesales. Stion has survived so far after lining up investments in Taiwan and Korea, and it started shipments from its Mississippi factory last year.

9). SoloPower: The company is another CIGS startup that has made progress toward commercializing its technology while its peers disappeared into oblivion. SoloPower turned on its 100MW factory in Oregon last year and secured a federal loan guarantee to help it expand if it meets milestones.

10). SCS Renewables: As interest in investing in solar power generation grows, investors will want to know where they can find quality projects. SCS Renewables runs a match-making service that also helps developers to massage their projects into presentable shapes in front of banks and other investors.

11). Silevo: With a new type of hybrid solar cell technology and its first factory in China instead of the U.S., where it’s headquartered, Silevo has mapped out a plan to scale up production and keep production costs low enough to attract customers with its efficient cells. 

12). TenKsolar: Out there in Minneapolis, tenKsolar has designed a wave-like solar energy system that pair solar panels with separate panels that are lined with a reflective film to direct light to the solar cells. The unusual design caught the attention of Korean conglomerate Hanwha, which led a $15.5 million round in 2012.

13). OneRoof Energy: The startup teams up with roofers and electricians to sell rooftop solar systems and financing products such as leases as part of new roofing or re-roofing projects. OneRoof Energy is part of a group of solar installers, such as the now public SolarCity and high-profile startups Sungevity and SunRun.

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Now researchers at the University of Cambridge are studying the light-harvesting proteins of the deep sea Green Sulfur Bacteria to see if they can provide breakthroughs for solar energy and other electricity devices. The research is in an area called quantum biology, and the scientists say it falls outside of ‘classical’ physics, and into quantum physics.

Organisms that do photosynthesis use a network of pigments held in place by protein structures, or what scientists call pigment-protein complexes, where electrons are harvested. In many organisms as the electrons move through these systems they lose energy. But in the Green Sulfur Bacteria they are able to move electrons through their photosynthesis system to the point of harvest without losing that energy on the way.

Raising the efficiency of solar cells (which make up solar panels) is very important work for solar companies. The higher the efficiency of the cells, the more electricity can be created by the panel and the fewer cells and panels needed.

Solar companies have been working diligently on these innovations in recent years, as the basic low efficiency solar panels become more and more commoditized. For example, Alta Devices, makes cells that can convert a whopping 28.8 percent of sunlight into electricity. But those types of cells are far more expensive than the standard cells, and many are still in the research and development phase.

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Alta unveiled two designs on Friday that are charging mats of 10-watts and 20-watts, both of which are much smaller than other solar charging mats out there. Alta plans to make the cells at its existing, 2 MW production line and hire another manufacturer to put the cells into the mats.

The company’s CEO, Chris Norris, told us Alta also plans to announce a military contract within the month, and from there raise a new round of funding in 2013 to build a 40MW factory, which could end up being located in Asia. Alta Devices was founded in 2007 and has raised $120 million in venture capital from investors such as Kleiner Perkins and Dow Chemical.

Solar-powered soldiers

A soldier’s pack could weigh 100 pounds, and over a third of that are batteries to power various communications and safety devices. Alta claims its solar chargers could reduce that battery heft by 70 percent, or roughly 25 pounds.

The company says it can pack more charging power into a small footprint than other solar cell developers because it’s developed a process for harvesting more energy from a set of materials that already are inherently better at turning sunlight into electricity than the more common materials. Alta’s solar cells can convert a whopping 28.8 percent of the sunlight they take in into electricity, compared with the mid- to high-teens that most common solar cells on the market can achieve today.

Why isn’t Alta targeting rooftop solar panels yet? Currently Alta’s panels are more expensive than the less efficient but abundant solar cells that have been flooding the market in recent years. So Alta had to look elsewhere for its initial set of customers, and the military, unlike utilities, power plant builders, and home owners, are more willing to pay a premium for more power in a small space. Down the road when Alta decreases its manufacturing costs, it could go after rooftops.

Alta is hardly alone among the solar manufacturing startups that have been forced to pivot their business plans because the market for conventional solar panels has way too many suppliers. That imbalance of supply and demand has caused high-profile bankruptcies of startups who couldn’t reduce their production costs quick enough. Solyndra, Abound Solar, Global Solar Energy and Twin Creeks Technologies are among the startup casualties.

The challenges that Alta and other solar startups have faced also are plaguing companies working on batteries for electric cars. Electric car sales haven’t grown as quickly as expected by tech companies, and that has sent battery developers to look for alternative markets, such as consumer electronics. But even there, the startups face tough competition from battery giants that have ruled the world of computers, cell phone and other mobile devices for a long time.

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While there are already a good number of solar covers for iPhones and even iPads, the problem is that most of these solar covers use conventional solar cells that are inefficient and take a long time to charge the device. Conventional solar cells also tend to be thick, bulky and heavy. But Alta Devices’ solar cells are up to 28 percent efficient (from less than 20 percent for conventional solar cells) and are created in a thin layer that can be embedded into materials, and buildings.

Alta Devices’s CEO Chris Norris (pictured in our photos) tells MIT Tech Review:

“Using our material, the cover of an iPad can generate 10 watts of power in the full sun. That’s the same amount of power you get from the wall.”

However, there’s a few things to remember about this move by Alta Devices. Alta Devices is looking to make money on some niche applications in the short term before it scales up production of its solar cell factories to make cells for buildings or utility fields. It’s not a good time to be a solar manufacturer, and in particular a startup solar manufacturer — dozens of solar makers have gone bankrupt or left the sector over the past year and a half.

Companies like Konarka have also been trying to make these types of niche solar products. Konarka recently declared bankruptcy after years of funding from venture capitalists. Alta Devices is also developing solar cells for military applications, which can enable troops and their devices to charge up off-the-grid in combat less frequently. Alta Devices tells MIT Tech Review that it can make a profit just on making solar cells for military applications.

To deliver its fast-charging iPad solar charger to the market by the end of 2013, the company will have to work at reducing the cost of its cells. At this point its cells are far more expensive than traditional silicon-based solar cells. Alta Devices makes it cells from gallium-arsenide. Check out this article for more details on Alta Device’s solar cell technology and a tour of its pilot factory.

Alta Devices has raised $120 million since its inception in 2007, and it’s building a pilot line that will be able to produce a few megawatts of solar cells per year. Its long list of investors include Kleiner Perkins, August Capital, Crosslink Capital, DAG Ventures, NEA, Presidio Ventures, Technology Partners, Dow Chemical, Alberta Investment Management Corporation (AIMCo), Good Energies, Energy Technology Ventures — the joint venture involving GE, ConocoPhilips and NRG Energy — and Constellation Energy.

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The gallium-arsenide compound is more efficient at converting sunlight into electricity than the more common semiconductors found in today’s solar panels, such as silicon, cadmium-telluride or copper-indium-gallium-arsenide (CIGS). But gallium-arsenide also is much more expensive and commonly used sparingly as one of several ingredients for solar cells.

Alta’s simulation and field data show that its solar cells can produce two to three times more electricity over a one-year period than those available on the market today, Norris said. The company broke the world record for gallium-arsenide solar cells last year with a 28.2 percent cell last year.

Experimental cells like that are typically made in labs and demonstrate what a company might be able to achieve after it starts to mass-produce them. Whether a company will ever do so will depend on factors such as its ability to raise money and operate factory equipment efficiently, and these hurdles have tripped up many venture-backed CIGS startups.

Earlier this month, Alta announced it was able to produce a solar panel with 23.5 percent efficiency. When solar cells are selected and assembled into a panel, there tends to be a small loss of efficiency. That’s why cell efficiency figures tend to be higher than panel efficiencies. The most efficient solar panels sold today are the 20 percent panels launched by SunPower last year.

While gallium-arsenide cells are more efficient and should fetch higher prices, they won’t attract many buyers if they are too expensive and require project developers to make a substantial upfront investment.

Alta’s secret sauce

Alta’s technology for cutting production costs focuses on creating ultra thin, 1-micron gallium-arsenide solar cells that are grown on re-usable gallium-arsenide wafers, Norris said. Using the same compound for the cell and wafer ensures that the crystalline structure of the two match, which minimizes defects and leads to more efficient cells than using materials with mismatched crystalline structures.

To slice off that top layer without damaging it, Alta creates an intermediate layer between the two, using aluminum arsenide. Aluminum arsenide has virtually the same crystalline structure as gallium-arsenide, making it a good substitute. Alta harvests that top layer to make solar cells by etching away the intermediate, aluminum-arsenide layer, Norris said. After that, the wafer at the bottom is re-used to grow more cells. The wafers, at $100 each,  are good to be used repeatedly as long as they don’t break.

Many research labs know how to grow and slice off the top layer in tiny pieces. “The trick is to do it on large pieces and make it possible to do it at scale,” Norris said of Alta’s challenge to commercialize the technology.

Alta wants to make cells and sell them to customers who will use them for making either conventional solar panels or other devices such as roofing materials. In fact, Alta is working with one of its investors, Dow Chemical, on a federally-funded project to embed solar cells in building materials. Dow already is selling solar shingles containing CIGS solar cells.

The startup has raised about $120 million since its inception in 2007, and it’s building the pilot line that will be able to produce a few megawatts of solar cells per year, Norris said. With an undisclosed equipment supplier, Alta has designed three key pieces of equipment for slicing off the top gallium-arsenide layer for making solar cells. The rest of the factory tools will be more or less off-the-shelf.  Commercial shipment should take place by the end of 2013.

Check out photos from our factory tour:

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Emefcy, which is using naturally occurring bacteria to treat wastewater and produce electricity, is getting an undisclosed amount from Energy Technology Ventures as well as Pond Venture Partners, Plan B Ventures and Israel Cleantech Ventures.

The Israeli startup, founded in 2008, said it will use the money to develop the technology and deploy it commercially by the end of this year. Emefcy will market its process to cities and owners of industrial systems, from food to pharmaceutical processing plants.

Emefcy is developing a microbial fuel cell that uses wastewater as fuel to produce electricity. The company claims its process is less energy intensive than aerobic or anaerobic digestion technologies. The process also yields treated wastewater that can find other uses. Recycling wastewater has a mass appeal for countries in parched regions of the world, such as the Middle East.

The idea to produce energy from wastewater, particularly from human wastewater, isn’t new and has been explored by other companies and academic researchers around the world. The Bill & Melinda Gates Foundation recently gave $1.5 million to a research project at Columbia University to develop a waste-to-energy technology to make water treatment cheaper for poor communities and to minimize wastewater contamination of local rivers and lakes. Many research institutions and companies also are studying and developing microbial fuel cells.

The same cost savings and environmental benefits are driving similar innovations in other parts of the world. Wastewater treatment today uses 2 percent of the world’s electricity supply, or 80,000 MW, at a cost of $40 billion per year, according to the press release about Emefcy’s funding. Deploying wastewater-to-energy technology isn’t cheap, so driving down that expense could help the technology get deployed more widely.

Emefcy is the first non-U.S. company that has lined up investment from Energy Technology Ventures, which made its debut in January this year. GE, NRG and ConocoPhillips said they will invest $300 million via the fund in a wide variety of technology areas, from solar to coal conversion. The fund’s portfolio companies include Alta Devices (ultra-thin solar cells), CoolPlanetBioFuels (biomass to fuels), and Ciris Energy (coal-to-methane conversion).

Image courtesy of Emefcy

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Alta Devices is combining the material gallium arsenide, which is already pretty efficient at converting sunlight into electricity, with a process that can harvest additional energy from the material. The ultra-efficient gallium arsenide cell is also super-thin yet able to convert more sunlight into energy than silicon and cadmium telluride cells: the two most widely used solar cell materials today.

An Alta cell is about 1 micron thick compared with 150-200 microns for silicon cells and roughly 15 microns for cadmium-telluride, Norris said. Making thinner cells is a goal for all cell developers because it cuts costs.

Alta has achieved 28.2 percent efficiency with its cells, an efficiency that breaks the previous record of 26.4 percent for gallium arsenide cells and has been verified by the National Renewable Energy Laboratory, the company said. At 28.2 percent, the cells are far more efficient than the most efficient silicon solar cells available on the market today. SunPower is making solar cells with 22.4 percent efficiency and panels at roughly 20 percent efficiency, the company announced earlier this month. First Solar, the world’s largest cadmium telluride cell maker, is making panels at 11.7 percent efficiency. Panel efficiencies tend to be 10-12 percent less than cell efficiencies.

The startup chose to use gallium arsenide because it is naturally more efficient at converting sunlight into electricity compared to silicon and other materials. But the chief reason gallium arsenide isn’t commonly used in solar cells today is its cost. Because of its high price, solar cell developers typically have used very little of it and only in combination with other materials to develop a type of multilayer cells that are found in solar electric systems that use mirrors to concentrate sunlight by hundreds of times onto the cells.

Alta’s technology was developed out of research from co-founder Eli Yablonovitch, a professor at UC Berkeley, who worked on a technique called “epitaxial lift-off,” which makes it possible to create very thin gallium-arsenide cells with internal structures that can squeeze more power from the sunlight that enters the cells. The tech enables a photon to produce more electricity after it has entered a solar cell, because when photons enter a cell, they tend to knock loose the electrons in the material and create holes that can hold those electrons. The free electrons can be collected and create current, which then combines with voltage from the electrical field in the cell to form power.

Not all the electrons in the process can be collected to create electricity, but the electrons that can’t be collected can be formed into photons, and can be used to knock loose more electrons to increase the overall power output of the cell, Norris said. The process of an electron becoming a photon again (after rejoining the hole) is called “radiative recombination. “It’s called photon recycling. What we focus on is making use of the primary (energy) loss mechanism inside the material,” Norris said.

Alta is still in the product development stages: It concocted the best cells in its lab. The company plans to build a pilot factory in Sunnyvale, Calif., and start producing cells next year, Norris said. The cells will be entombed in plastic materials to keep moisture out and make the cells flexible for many applications, and Alta wants to sell cells to companies who will assemble them into panels or embed them in roofing and other building materials. Alta also will likely produce its own panels as well.

The plan is to start commercial shipment in 2013.  “Nobody has commercialized a gallium arsenide thin film yet. We are going to be the first to do that.” Earlier this year, Alta said it had raised $72 million from investors including Kleiner Perkins, Dow Chemical and a joint venture among GE, ConocoPhilips  and NRG Energy.

In Monday’s announcement, Alta Devices mentioned research by one of its co-founders and Caltech professor Harry Atwater, who is presenting a paper about silicon microwires. The silicon microwire research is actually not related to what Alta Devices is working on, Norris said.

Image courtesy of the NASA Goddard Space Flight Center

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