For the nerds out there who want to learn fun details of solar technology without taking engineering classes, we have a brief intro to solar parabolic troughs.

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.

Utility-scale solar power requires setting up large arrays of solar panels on open land. Since large tracts of sunny, unused land are pretty hard to come by, large-scale solar developers occasionally face opposition from stakeholders who ascribe other value to land that could otherwise be developed for solar.

The latest of many land use debates in solar development has arisen as a response to Tessera Solar’s 709 megawatt (MW) project in the Sonoran Desert near El Centro, California. The Native American Quechan tribe is filing a lawsuit against the federal government, arguing that the project would deplete “cultural and biological resources of significance” on public land. The tribe believes project overseers did not take Quechan concerns into account during the power plant’s permitting process, which could violate federal law. The most salient resource of cultural and biological significance to the Quechan tribe, according to the LA Times, is the flat-tailed horned lizard, which  has a significant role in the Quechan creation story.

Tessera Solar has offered to purchase an additional 6,600 acres of designated lizard habitat to offset the habitat limits that their project creates, but negotiations have yet to reach a clear conclusion. Similar debates have occurred over habitat for the desert tortoise in the past, and many have watched with puzzlement — and small dose of irony — as renewable energy advocates and conservationists were suddenly at odds with each other.

There are no easy answers in land use debates where multiple stakeholders have very reasonable interests. However, the challenges involved in utility scale solar plant development actually highlight the benefits of distributed solar energy generation — whereby a large number of small-scale systems are installed on space that otherwise is of little use. Putting solar panels on your roof just got that much more appealing.

Following the planned 2012 release of Tesla Motors’ highly anticipated Model S sedan, CEO Elon Musk just announced that Tesla will release an electric-powered SUV just 2 years later: the Model X. The Model X will use the same “adaptable common platform” as the Model S, but will boast a slightly more specialized battery pack. It’s exciting news for followers of green technology and energy issues in the broadest sense.

But what does this have to do with solar energy, you ask?

Transferring from cars that run on oil to cars that run on electricity only makes an environmental impact if the fuel you use to run your new car is cleaner than the fuel you used to run the old one. In short, if you get all your electrical power for your Tesla from coal, then your environmental impact is not so different from someone driving a gasoline-dependent car. You might help reduce dependence on foreign oil, but the dirty electricity is still problematic. That’s where solar comes in.

Elon Musk, Tesla Motors’ CEO, explains in a company blog post:

…the overarching purpose of Tesla Motors (and the reason I am funding the company) is to help expedite the move from a mine-and-burn hydrocarbon economy towards a solar electric economy, which I believe to be the primary, but not exclusive, sustainable solution.

Telsa’s amazing strides in making our transportation greener is fueled by a desire to make our overall energy use more sustainable. Solar energy, along with other renewable energy sources, plays a tremendous part in setting us up to achieve this goal.

We’ve been talking a bit about solar manufacturing processes at GetSolar lately, since most (if not all) of the innovation in solar energy generation occurs at that stage. Most discussion of solar manufacturing revolves around how to best reduce cost. But the amount of energy used to manufacture solar photovoltaic (PV) panels — also called solar “modules” — often merits attention as well. It takes effort and energy, after all, to fabricate the various parts of a solar module, like the solar cells, backsheets, frame and wires.

So, do solar panels generate more electricity than the amount of energy that goes into them? In other words, are they energy net positive? We’ll use a simple payback period to take a look at this question.

Energy Used in Manufacturing / Energy Generated per Year in Use = Energy Payback Period.

The energy payback periods for solar panels have come down significantly over time, with most recouping their energy consumption in two to five years. Since solar PV panels typically have a useful life of 25 to 30 years — and sometimes even longer — solar offers a very good long term energy generation option.

The National Renewable Energy Laboratory publishes some detailed information on this topic; in addition, you may find this overview from the U.S. Department of Energy helpful. Because no two types of solar panels are exactly alike, the authors draw distinctions between the energy payback periods for individual solar technologies, including current multicrystalline, current thin-film, projections for multicrystalline, and projections for thin-film.

With improving technology, thin-film solar panels could reach a one year energy payback period! That’s impressive — especially given the lifecycle costs of other energy sources. Solar has a great energy payback already, and it’s only getting better. Keep your eyes peeled for improvements in solar technology and manufacturing to follow how this metric improves over time.

1366 Technologies raised $20 million this week in second round funding from Hanwha Chemical and Ventizz Capital, along with earlier investors Polaris Venture Partners and North Bridge Venture Partners. 1366, whose name refers to the amount of sunlight hitting the earth (1366 watts per square meter), has developed a solar manufacturing process that will cut the cost of solar cells by 40 percent.

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.

Massachusetts Institute of Technology is tinkering with another creative solution to their daunting research task of improving solar energy. Just one month ago, they announced regenerative solar cells, a type of solar cell mimicking plant cells’ regenerative abilities to keep their efficiency high in the face of sun damage. Now, MIT has produced a paper-thin solar cell that could be used to cover windows.

Unlike their earlier breakthrough this year, these cells address a less technical hurdle that solar energy faces: aesthetics. Many would-be solar enthusiasts don’t want to place solar panels on prominent rooftops or yards for fear of having them simply look ugly. (Ed.: We here at GetSolar don’t share this fear. Solar panels are downright pretty.) These clever panels could function like normal blinds, side-stepping the problem entirely.

According to CNET News, the prototypes displayed yesterday in Boston created enough energy to power a modest LED display. Chemical engineering professor Karen Gleason, who conducted this research in collaboration with an Italian company called Eni, believes a commercial device could be available in five years. She imagines the blinds could be connected to home wiring or have a built in energy storage system.

Though efficiencies of these early prototypes are low, the real power of the invention lies in the materials used and the “layer by layer manufacturing process” that Gleason’s lab is pioneering. These factors have the ability to make the cells radically inexpensive. They won’t use any pricey or rare metals found in some other solar cell designs.

This technology’s ability to cut costs and aesthetic hurdles simultaneously could make it a gamechanger. We’re hoping to see more prototypes from Gleason’s lab as the research progresses.

It sounds miraculous to say that the right combination of metals can create electricity just from laying out in the sun. For anyone who’s ever wondered about this, here’s a brief explanation aimed at non-engineers.

The whole point of a solar cell is to get electrons moving. That’s all electricity is, after all, a current of moving electrons. You have to create this by luring electrons away from the nuclei of the atoms to which they belong. The energy from sunlight can accomplish this, but it takes a certain combination of elements to make it work well.

You start with a semi-conductor like silicon that forms a stable lattice at the atomic level. It shares its four outer electrons with surrounding atoms, giving each atom the eight outer electrons it needs for stability. (Eight valance electrons makes an atom stable and unlikely to bond.) Because it forms such stable bonds, silicon doesn’t promote the flow of electrons, making it a less than perfect conductor of electricity.

To improve it, you add specially chosen impurities: phosphorus, which has one more outer electron than silicon; and boron, which has one less. Boron is added to one layer of silicon, whose lattice now is missing some electrons, and phosphorus is added to a layer above it, which now has extra. The intersection of these layers is called the P-N Junction. When sunlight adds energy to this system, the extra electrons immediately move between the layers, generating electricity in the process.

Is this actually more complex? Sure it is. Some people go to school for years to understand how this process and ones like it work in detail. However, it’s fun to hear a little about how an amazing technology works. Solar technologies are constantly improving too. They have already grown more efficient and less expensive. The evolution is a fun process to watch — and it’s even better to be a part of it by using solar yourself!

If you’ve noodled around on the Web looking for information on residential solar energy systems, you may have come across something called a “Solar Renewable Energy Credit” — or SREC (pronounced “S wreck“) for short. Since SRECs help make solar panels a great investment in some states, we figured it might be helpful to explain what these credits are and how they work.

We’ll start with the textbook definition: An SREC is a certificate representing the “green attributes” of one megawatt-hour (MWh) of electricity generated from solar energy.

What does this mean in practice? If you install solar panels on your home, you roof will, in effect, start generating kilowatt-hours (kWh). As these kWhs add up, you’ll be on your way to making one SREC — which, as noted above, is the equivalent of one MWh, or 1,000 kWh.

How many SRECs does a system produce? It depends generally on the size of the system and the amount of sunshine available. By way of example, a 7-kW home solar energy system in Somerset County, New Jersey, would, according to our solar cost calculator, produce roughly eight SRECs over the course of a given year.

Now comes the good part. Once you’ve accumulated an SREC (or two or three), you’ll be able to sell your credits. Exact SREC prices vary from state to state, but the highest price recorded so far has been around $680 in New Jersey. At this price, SRECs would generate $5,440 in annual revenue for our hypothetical 7-kW solar array in Somerset County. Put differently, we would earn $0.68 for every kWh that our system produces — this in a state where the average residential price of electricity is around 16 cents. Clearly, SRECs in New Jersey provide a generous incentive!

To be fair, SRECs are traded actively in only a handful of states — but that number is growing. Also, it’s important to note that the going price of an SREC tends to fluctuate, and that $680 levels are likely the exception, not the rule. Finally, in some states, like Colorado, utilities offer an upfront payment for all the SRECs a given system is expected to generate — rather than buying them over time.

How did all this SREC business get started? Many states have passed a Renewable Portfolio Standard (RPS), legislation requiring them to produce a certain percentage of their electricity from renewable resources by a certain year. For example, New Jersey’s requires the state to produce 22.5 percent of its electricity from renewable resources by 2020. State requirements vary based on their political support, baseline level of renewable electricity in use, and level of public investment. An RPS almost always includes a policy plan to incentivize renewable energy development and installation within their state. In the residential sector, this is most traditionally done though subsidies awarded based on the number of watts of renewable energy installed. California’s solar rebate programs, for example, award a per-watt payment to homeowners who install solar panels.

Many states include a provision specifically for solar energy, requiring a smaller percentage of total renewable energy to be met by solar photovoltaics. Each electricity provider that does not meet this percentage must purchase SRECs to correct their deficit, and non-compliance means a hefty fine. As a result, SRECs are sold for prices determined strictly by the market for RPS compliance. It’s a simple case of supply and demand: fewer solar installations means higher prices for available SRECs, creating an incentive for future solar installations.

So far, Delaware, Maryland, Massachusetts, New Jersey, North Carolina, Ohio, and Pennsylvania, have funded and implemented SRECs to promote the level of solar energy development that their policies demand. To see how SRECs might affect your solar system, check out our solar cost calculator. Or, if you’ve got burning questions, post them below!

Chevron CEO John Watson gave an interesting interview for the Wall Street Journal this week on the role of renewable energy in the current energy marketplace. Like most people offering opinions on the subject, Mr. Watson has a bias based on his role. He may not be the world’s greatest renewable energy advocate, but his perspective on changes in the energy market is still worth considering — and debating. A few highlights:

1. Fossil fuels have helped us create the standard of living we have today. I don’t think anyone contests this. There are also many feasible alternative energy resources available today that can help us maintain that standard of living.

2. The transition to renewable energy will occur, but we need more time — probably multiple generations. To eliminate fossil fuels completely, this may be true. However, that doesn’t mean we can’t limit our use of them. There are many viable alternatives to fossil fuels. For powering residential and commercial buildings, at least, solar and energy efficiency work wonders.

3. The energy business is a huge business, so it will take a long time to change. I beg to differ. Renewable energy is growing more rapidly than any other energy resource, and newer companies are stepping in to meet demands that their more established counterparts overlook. The solar industry, for example, has undergone rapid growth and change. It is true that major infrastructure investments like power plants have long lifetimes, but that doesn’t mean that the industry stays stagnant. From our perspective, the times really are a changin’.

4. Chevron will invest over $2 billion in renewable energy in the next 3 years. That figure sounds much more significant than it actually is in the world of energy investments, but it’s still very notable. Mr. Watson cited his company’s investments in biofuels and geothermal power as examples.

At the end of the day, the energy industry as we know it can’t change overnight, as Mr. Watson clearly explains. However, the role of individuals’ modifying their own energy use — via solar energy, efficiency, or other renewable energy options — creates noticeable, significant change. That’s the only way we ever move forward right?

Solaria Corporation yesterday announced it raised $65 million in series D financing to expand production of their solar modules, which are designed specifically for ground-mounted tracking systems. The company uses a manufacturing process that “requires only a fraction of the capital expenditure per watt of manufacturing capacity needed by standard industry practices.”

Now that’s kind of a big deal. Whenever the future of solar comes up in conversation, one of the first things you’ll hear is how great things will be “when we drive down the cost of solar panels,” or more ambitiously, “when we reach grid parity.” The problem with that kind of rhetoric is that it usually lacks specific details about progress being made toward these goals. Solaria’s news, however, was a lot more tangible and just as exciting. They have found and patented a way to manufacture solar panels at a fraction of the current cost.

Solaria explains their cost breakthrough on their company website, highlighting an unusually short “energy payback” for modules with complex tracking technology:

PV already has an attractive “energy payback” of about 1.9 years, meaning that the energy required to produce a PV module is generated in 1.9 years of operation. Solaria brings the energy payback to less than 1 year, further contributing to PV’s role as a leading energy solution with negligible carbon footprint in its creation.

Investors seem to agree that this invention matters, coughing up $65 million is this round of funding. The funding will be used to increase availability of Solaria’s panels worldwide, and it includes a $10 million growth loan facility. Solaria saw investments from Adams Street Partners, Cycad Group, enXco, Western Technologies (WTI), CMEA Capital, and DBL Investors.