So today we’re going to delve into one of the most important pieces of your solar energy system: the inverter. The solar energy that your PV solar panels generate is direct current (DC), meaning it flows in a single direction. The inverter converts the electricity into alternating current (AC), so that the it can flow back and forth and feed electricity to different areas of your home.

The solar PV energy system atop your home or business likely features several PV solar panels wired together in series in a single row, or multiple rows depending on the size of your solar energy system. Conventionally, the PV solar panels have to be wired together so that all of the electricity that the PV panels produce is fed into a single inverter.

But there is a new type of inverter that changes the rules of the game: the microinverter. Microinverters are installed on each individual panel. So each panel produces AC power on its own. As a result, the solar PV panels don’t have to be wired together to flow energy to a single inverter.

Today, microinverters are not as common for solar energy home installations because they haven’t been around as long as conventional inverters. Panels equipped with microinverters cost a bit more, too, but they may generate more AC output per panel than a system with a conventional inverter.

If you’re interested in PV panels with micro inverters, talk to your installer about it before choosing a system. And be sure to check out this podcast courtesy of Renewable Energy World in which solar industry professionals debate which type of inverter is best to use. Also interesting is this 2009 article from MIT’s Technology Review.

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RE<C, or “renewable energy cheaper than coal,” is arguably the most important of all of the company’s programs, as it deals with the greatest obstacle between us and wide-scale renewable energy use: cost. Here are three main steps Google.org is taking through RE<C to make renewable energy cheaper than fossil fuels:

1. Give grants to and invest in companies and technologies working toward making renewable energy more affordable than energy produced at coal-fired plants.

2. Support public policies that accelerate renewable energy development.

3. Use its own technology to spread information and raise awareness about the benefits of renewable sources of energy.

In 2008, Google invested over $45 million through RE<C alone in companies it views as having breakthrough technologies in solar energy, wind and geothermal power. Google is also sponsoring a project to create what it calls the first, “Geothermal Map of the World.” The map will help reveal resources underground that are currently hard to detect, and show an area’s potential to develop and deploy clean energy. Check out this video to see how the map would work.

The Clean Energy 2030 Plan was first introduced in October 2008 and is far from over, as Google sees the need for $4.4 trillion in investment between now and 2030.

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One is the Crescent Dunes Solar Energy Project, whose developers earlier today earned federal approval for construction. The plant will be built by SolarReserve — a Santa Monica, California-based solar construction company that last week received approval to build a 150-megawatt (MW) Rice Solar Energy Project in southern California.

At 110-MW, the Crescent Dunes project is a bit smaller, but will still have a large impact on the surrounding economy. Beyond producing enough energy at peak output to meet the energy requirements of roughly 75,000 average American homes each year, Crescent Dunes will also create about 450 construction jobs.

The second major announcement included another California solar power project developer, Sustainable Energy Capital Partners (SECP), which revealed its plan to partner with POSCO Power to build a 300-MW solar installation in Boulder City, Nevada. Following completion, the Boulder City solar plant will be able to power about 135,000 average American homes each year. If all goes well, the plant should be up and running by the middle of 2011.

While POSCO Power and SECP are touting the venture as the biggest solar power plant in the world, it probably won’t be for long. If all goes according to plan, the Blythe Solar Power Plant in Riverside County, California, will have a generating capacity of 1,000 megawatts — or one gigawatt.

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MIT’s Associate Professor of Power Engineering Jeffrey Grossman is leading a research team that is developing what they hope becomes the world’s first liquid solar storage battery – able to infinitely store and transport solar power captured by photovoltaic (PV) solar panels. The research comes just three months after MIT’s SENSEable City Lab unveiled “Seaswarm“- a solar-powered, oil-sucking robot that would be able to clean up future oil spills similar to the Gulf Coast oil disaster this past summer.

The research team has discovered that fulvalene diruthenium – a molecule that comes out of the  rare transition metal, ruthenium – absorbs sunlight and changes it into what Discoverycalls a, “semi-stable condition.” Then, when a catalyst is added to the stable power, the energy reverts back to its original form and  can be used for heaters or appliances. Here’s  how Professor Grossman proposes the technology be used in liquid form:

 ”…one possible picture would be that the fuel could be placed out in the sun in deep pools, and throughout the day the fuel would get charged by the sunlight. Once charged it can be pumped and delivered (through pipes, or other means) to a point of use — that could be nearby or far away.”

Grossman’s “far away” transportation plan is the key element here. Less than a week ago, Arizona State University Assistant Research Professor Matt Croucher published his research in the Electricity Journal saying that, if the United States is ever to realize its full solar potential, Arizona would have to transport a major percentage of its solar energy to states with high utility rates.

The news out of MIT concerning the liquid battery research comes on the heels of a report released by one panel of the American Physical Association (APA) saying the United States Department of Energy (DOE) must develop grid-level energy storage with a review of different battery chemistries – much like the chemistry being used by the MIT team.

The one catch with this new method is that diruthenium is an extremely expensive molecule. So now the search is on for a cheaper alternative to replicate the process. Stay tuned…

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Nope — these don’t look like the panels that grace the rooftops of homes and buildings to generate clean electricity. Parabolic troughs are solar thermal technology: they use the sun’s heat to directly generate energy. Photovoltaic (PV) panels take a different approach, using panel materials to create an electric current without utilizing heat. These parabolic troughs, and solar thermal electricity in general, are used in large, utility-scale solar farms.

They function by concentrating heat from the sun onto a receiver pipe in the center of the parabolic curve (see the horizontal grey pipe above). The curved surface allows the system to concentrate heat to 30-60 times its natural intensity, and this heat is transferred to the synthetic oil circulating through the receiver pipe. This heated liquid is then sent through a heat exchanger, producing steam that spins a turbine and generates electricity.

Solar trough predominate utility scale solar plants in the United States, and 2010 actually marks the 25th anniversary of the first solar trough technology implemented domestically. This solar plant in the Mojave Desert achieves daily net efficiencies close to 20 percent.

For a seemingly strange-looking solar technology, parabolic troughs play a fairly significant role in the solar market.

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Yesterday, the group announced it has acquired a submarine tour business to offer visitors “undersea adventures using quiet, electric-powered submersible vehicles with near-zero environmental impact.” Hidden at the bottom of that press release was a reference to Nabisolar, a solar installation company with which HHGI has partnered to introduce solar power to a number of the developer’s properties.

While the size and scope of the soon-t0-be installed solar energy systems has not been disclosed, HHGI apparently already offers design and installation services to other eco-tourism business in Hawaii through its relationship with Nabisolar. With their high electricity prices and strong solar incentives, Hawaii is an excellent place to install a solar energy system for a home or business.

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Their process can cut costs so dramatically because it involves a unique method of converting unprocessed silicon into usable wafers. This process reduces the cost of the silicon wafers, a key component of solar cells, by 80 percent. In the conventional manufacturing process, silicon is cast into big ingots or grown in giant crystals, then sawed off into thin slices. The result is a lot of wasted silicon, which is brittle and can turn to dust during the process. 1366′s approach is less wasteful, as explained by the New York Times:

The new technique, going from molten silicon to final product, is a bit like frying pancakes as opposed to slicing salami, except, as Mr. Danielson put it, “when you cut a salami, it’s not like half the salami ends up as salami dust that you have to throw in the garbage.”

MIT Professor Ely Sachs invented the process in 2009, and now 1366 plans to use its funding to build a factory for small scale production of its radically inexpensive technology. 1366 will begin selling its silicon wafers in 2012, and we’re all hoping to see this technology alter the solar world in a big way.

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To be integrated on an electricity distribution lines in Flagstaff, the pilot project is one component of the smart-grid initiative currently taking place in northwestern Arizona. The other half of the initiative, according to Renew Grid, is the community power project, a residential solar power program that will test the effects of a large amount of solar energy flowing through a lone distribution line.

The APS plan’s aim is to speed the repair of outages and entails mounting sensors on two Flagstaff power lines that communicate with a central computer system. When there is an outage, the devices locate and isolate the disrupted area and restore power along the rest of the line.

Right now when outages occur, APS workers know which lines are affected but are unable to pinpoint trouble spots with much accuracy. This new technology tells workers the exact location of the problem. APS Director of Smart Grid Development Barbara Lockwood sees these devices as a huge time saver for APS and for its customers:

“These devices could cut down on the number of people affected by outages and the time it takes for APS to respond and make repairs. When perfected and widely deployed, this technology could be a game changer.”

APS says that in some of the simplest outage cases — where all that needs to be done is close an open circuit breaker — the devices may even be able to address the issue themselves.

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Solar panels need (micro)inverters to convert the electricity they produce to a type that can be used at home. Solar photovoltaic panels produce DC (direct) electrical current, and household appliances use AC (alternating) electrical current. AC and DC refer to the direction that electrons flow when electricity is created. Technical details aside, the key point is that electricity produced by solar panels must be converted from its raw form to a more usable one. Inverters make this conversion possible.

Micro-inverters perform this energy conversion for individual panels or small groups of them, not for the entire system. Traditionally, a solar system would have one inverter for all of the panels, which limits the amount of equipment needed. However, micro-inverters offer a definite efficiency advantage. Here’s why: With a traditional inverter, the solar system can only reach the efficiency of the least efficient panel. Efficiency can vary because of dirt on the panels, shading, or mechanical malfunctions. If each panel has its own inverter, however, all can operate at their maximum possible efficiencies, optimizing the amount of electricity produced in the whole system.

Rapidly improving micro-inverter technology has enabled the growth of “plug and play” solar systems, like the Clarian Sunfish, which was recently profiled in the New York Times. This product and its competitors offer very small scale solar panel systems that can simply be plugged in to start generating electricity, bypassing a more complex installation process.

Micro-inverters are used less frequently for larger commercial or utility scale projects, although there is an ongoing debate over whether or not they should be. For more detailed information on where micro-inverters and traditional inverters are best used, check out the Renewable Energy World podcast Microinverters vs. Central Inverters: Is There a Clear Winner? along with Greentech Media’s article Can Micro-Inverters Penetrate the Megawatt-Scale PV Market?

Technology in this area will continue to evolve. It’s a fun topic to follow.

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One is the Rucksack Enhanced Portable Power System (REPPS), developed by the U.S. Army Communications-Electronics Research, Development and Engineering Center (CERDEC) Army Power Division. REPPS is a lightweight device that can charge laptops and other electronics of similar energy needs. Made up of flexible photovoltaic (PV) modules, it is a continuous power source that will allow soldiers to carry solar-powering stations in their rucksacks. A series of connectors and adaptors allow multiple devices to be charged. If there is a need to charge something high-powered, the REPPS can be chained together for increased potential. REPPS is capable of charging electronics in five to six hours.

The other technology is the Reusing Existing Natural Wind and Solar system (RENEWS), a hybrid wind-solar energy system that is meant for soldiers’ higher energy needs. RENEWS is larger than the REPPS and requires a team of two to transport it around. The reason for it s size is because it incorporates a battery storage. The panels and turbines collect and store the energy in the battery, and devices are charged through AC/DC outlets.

Thanks to the American Recovery and Reinvestment Act (ARRA), through which the manufacturing and deployment of the renewable energy systems are being funded, more than 700 REPPS and 125 RENEWS will soon reach soldiers in Afghanistan.

For more on the armed forces are making use of solar power, check out “U.S. Marine Corps Gets Solar in the Field.”

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