Much Better Solar Photovoltaics On the Way

Startup Enphase Energy of Petaluma, CA, is now making its first micro-inverters.  The small inverters can be bolted to the racking under each of an installation’s solar panel to convert DC power into AC for each panel individually. The company claims that the devices will increase a PV system’s efficiency by 5 to 25 percent and decrease the cost of solar power.

Enphase has already teamed with various distributors and partners, including solar module manufacturer Suntech Power Holdings and installer Akeena Solar, to bring its device to customers.  The micro-inverters can be used on residential, commercial, or even utility-scale photovoltaic systems.

There’s much more to solar power than black glassy panels glistening on rooftops.  Perhaps more important now that installations and real world testing is well underway and understood is the inverter performance that convert DC power created by the solar panels into grid-ready AC power.

Currently all the panels in a rooftop photovoltaic system are connected to one large inverter mounted on the side of a house from which the AC power is off loaded to the house or grid.  This is being done as solar panels are wired together in series, and their combined high-voltage DC power is fed to the inverter. From that current flow the inverter’s logic circuit optimizes the total current and voltage levels. But if one panel’s current drops, it becomes the limit of the overall output of the system.

SolarPanel Microinverter by Enphase
SolarPanel Microinverter
by Enphase

Leesa Lee, director of marketing at Enphase points out the problem, “Something as simple as a leaf blowing over a module, or dust or debris or shade on one module, will affect the entire array of all those modules that are connected in series.”  Think bird poop and all the other things falling out of the sky as major problems, but mostly canceling the equality of each panel, that forces production to the least efficient module.  It’s a bigger problem than many realize.

But Enphase’s micro-inverters individually optimize the voltage-current levels at each panel. That uses the most power from each panel and then adds the panels together, increasing the system’s efficiency. “Any problem on a module is limited to that module alone,” Lee says. In addition, the equipment cost for micro-inverters is about 15 percent less than the cost for a traditional system, she says, because expensive DC components, such as signal combiners and disconnects, can be replaced with off-the-shelf AC parts.

Enphase Micro Inverter Points. Click image for a larger view.
Enphase Micro Inverter Points

The problem has been known for decades so the concept of small inverters has been around for more than a decade, but there have been technical challenges to making practical devices. Enphase’s Senior Director for Systems, Mary Dargatz says,  “One of the biggest stumbling blocks to micro-inverter technologies in the past has been conversion efficiency.” So, Enphase has converted many analog parts in the circuits to digital to make the inverter smaller without sacrificing efficiency. The conversion efficiency of an individual micro-inverter is 95.5 percent, on par with efficiencies of traditional large inverters, which range from 94 to 96 percent.

Seems odd, doesn’t it?  The most costly part of a system is hooked up in a 40 year old design that cuts down on the output.  It’s a habit from the 1960s when inverters were very expensive.  Now with micro-inverters on can add to a system without making the inverter, the second most expensive part obsolete. It may be that the micro inverters can be used to upgrade older systems as well.  Enphase offers a long list of downloads to assist owners and installers with analyzing and assessing how the new micro inverter can be used. Its well worth looking over.

Going partway in an attempt to address a broader voltage range, National Semiconductor is making a power-optimizing module for individual panels.  The device only has the logic circuit for optimizing current and voltage levels–it doesn’t do the DC-to-AC power conversion.  What it offers in conversion efficiency looks to be meant for existing installations.

Enphase uses its AC output and ease of connection to offer another service to backup the sale.  The full kit would allow a consumer to send data in for analysis and receive reports via the Internet.  Beyond that, the potential exists for rationing power, if the situation allows, to divide one’s output say for use in the home and for sale.

It all makes for a much more practical implementation of solar arrays with photovoltaic collector panels.  A drop in panel costs, now a drop in inverter cost and a simpler installation should help get home and small commercial arrays more deeply down into the economy where more people can afford the investment.  That more mass market, which should reduce prices as well.

Which brings us to what might be the most important advantage of all.  With the Enphase micro-inverter one can start small and add modules or panels as the budget (or incentives) allow.  Now that’s a path to help build more market, too.  Growth looks good for photovoltaic.

Here is the original post: New Energy and Fuel

Renewable Energy Explained

In contrast to the fossil fuels, renewable energies, as the name suggests, exist perpetually and in abundant quantity in the environment. They areready to be harnessed, inexhaustible, and more importantly, they are environment-friendly. However, the term “renewable energy” has no official or commonly accepted definition.

As an example, the Renewable Energy Working Party of the International Energy Agency defined renewable energyto mean energy that is derived from natural processes that are replenished constantly.

Typical renewable energy sources are wind, heat & light from the Sun, oceanwave, purposely-growth energy crops, potential energy of running water, geothermal energy, etc. Energy generated from waste is termed as one  kind of renewables in some countries. Others regard it as a waste disposal process rather than a renewable source, since there are pollutants generated as by-products, although modern technology has significantly reduced the pollutant emission to a very low level.

Modern solar thermal technologies capture sunlight and utilise its energy to produce hot water, steam and electricity. Apart from using purposely designed equipment to capture the solar energy, buildings in cold countries can be designed to make the best use of the heat energy from the sun by incorporating appropriate design features such as large south-facing windows and special building materials that absorb and slowly release thesun’s heat for warming the building interior.

Solar photovoltaic technologies, on the other hand, employs photovoltaiccells made from semi-conducting materials such as silicon to produce directcurrent electricity when they are exposed to the sun. In the absence of moving components that are subject to wear and tear, photovoltaic cells canoperate for a very long period without much maintenance commitment. Thesimplest and most common type of photovoltaic cells provides power towatches and calculators, while the more sophisticated “state-of-the-art” photovoltaic systems can generate electricity to supplement local consumption in a building or a designated system, and the excess power caneven be fed to the city electrical grid.

Wind is the movement of air molecules, resulting from variations in airpressure created by difference in solar heating over the earth surface. Wind turbine is a device which captures the kinetic energy of wind to turn agenerator for producing electrical power. Nowadays wind farms employing groups of wind turbines located either on land or on near-shore waters are becoming more and more common to harness the wind energy for mass production of electricity.

Other forms of renewable energy technology like hydroelectric power, wavepower, geothermal energy and energy form vegetation are also gaining increasing popularity in power generation. However the exploitation ofthese forms of renewables is very often dictated by geographical conditions, and thus the extent of their application usually has a wide variation amongst countries.

Municipal solid waste commonly refers to residential and commercial refuse, and takes up the largest percentage of waste generation in industrialized countries. There are three basic processes that are currently used toconvert municipal solid waste into useful heat or electricity, viz, thermal process, biological processes, and landfill gas utilisation. All three methods produce energy from organic materials present in the waste that would otherwise be converted naturally into methane or carbon dioxide; both are undesirable by-products as they are the main constituents of greenhouse gases.

10 Ways To Make Your Landscape Greener This Spring

The trend is clear-more and more homeowners are transitioning to a greener, more eco-friendly way of creating and maintaining beautiful landscapes. The benefits of making your landscape greener than ever this spring reach far beyond the positive environmental impact alone. In fact, going organic in your landscaping and lawn can even save money while providing a better looking outdoor space than ever before. Here are 10 remarkably easy and effective ways to make your landscape greener than ever this spring.

One: Make sure your soil is perfectly balanced.

Having your yard’s soil tested for its organic composition-both positives and negatives-is a fantastic way to start with a healthy and supportive palette. Simply take a representative sample of your soil, send it for analysis, and follow the recommended steps to bringing the soil back to it’s maximum organic potential. Here’s a helpful article explaining exactly how to have your soil analyzed. The ultimate benefit? Landscapes with the right blend of rich soil to support growth and water absorption means that the use of additional chemicals and water to keep the vegetation healthy will be reduced by a remarkable amount.

Two: Scale back too much lawn.

By its very nature, grass lawns are very durable and easy to maintain. But with the perfecting standards we’ve come to expect today, lawn care perfection has practically become an intramural neighborhood competition. Having a green and luscious lawn is certainly desirable, but why not scale the proportions back a bit to reduce the need for all of that extra fertilizer, pesticide, and water use?

Three: Eliminate strong chemical products.

Believe it or not, one of the best possible ways to achieve a healthy, thick lawn is to wean it off of all of the complex and harsh non-organic fertilizers and pesticides. Traditional organic substances like manure and lime can help your yard find a perfect balance-effectively creating a stronger root system and a significantly higher resistance to weeds and other common turf problems than a chemically-supported “surface only” lawn will ever develop. Plus, with an all organic lawn, there’s no need to worry about letting the little tikes play in the grass to their hearts’ content!

Four: Manage your landscape’s watershed.

Landscaping designs with lots of concrete and other unnatural “hardscapes” all to often have the unfortunate effect of directing a great deal of rainwater into the storm sewer system-along with all of the chemicals and non-organic materials it mixes with along the way. Eventually, all of these non-organic substances end up polluting the clean water sources we rely on. By allowing much of the runoff water to be naturally absorbed by the organic landscape, you’re home’s landscaping will actively be taking a load off of an already over-stressed water system.

Five: Landscape greener by planning more sustainable plantings.

Are you familiar with the concept of xeriscaping? If not, this spring is the perfect time to learn more about how to plan a xeriscape. Basically, the concept involves designing and maintaining a landscape plan that requires minimal irrigation-reducing the usage and pollution of our precious resources. Learn more with this quick and easy guide to xeriscaping.

Six: Add a solar powered water feature.

Water, the refreshing and renewing resource that we all so vitally depend on, is naturally the perfect way to create a soothing and reflective landscape centerpiece. What’s the perfect green solution? It’s simple-creating a lovely fountain or waterfall powered by the abundant energy of the sun itself. Creating a solar powered water feature will be a true highlight in any backyard paradise!

Seven: Remember that compost is your landscape’s best organic friend.

The rich and natural nutrients provided by compost should be a part of every organic gardener’s portfolio of gardening and landscaping essentials. Creating a composting system is easy enough to do for just about any home. And, the wonderful “black gold” fertilizer that composting provides would only end up in the trash bin if it wasn’t used to create the most effective organic fertilizer that money just cannot buy!

Eight: Eliminate weeds by growing healthier lawns.

Again, achieving the right balance in your outdoor landscaping design is always essential, but one thing is certain for those looking to reduce the growth of weeds in a grass lawn organically. By making sure the soil is full of the right nutrients and ensuring that the lawn is properly watered (but not over-watered), the resulting deep-rooted lawn means that less weeds will be able to penetrate the grass. Another reliable organic method of encouraging a strong root system is having periodic aeration done as necessary.

Nine: Set up a rainwater collection system.

What better way to provide plenty of water to your landscape’s ever-thirsty vegetation than to collect, store, and distribute plenty of clean water right from the clouds for free? Harvesting rainwater to provide or supplement your landscape’s watering needs is easier than you might imagine. Plus, using this water has a double benefit effect-not only does it reduce your consumption of processed water, but it also helps reduce some of the pollutant laden runoff water that clean rain water so often turns into as it works its way through the chemical rich landscapes and dirty streets back to its source.

Ten: Use internal combustion fueled power tools less.

Agreed, the gasoline powered lawn and garden tools we’ve become accustomed to over the years sure do make caring for landscaping a breeze. But the thing is, they also pump great quantities of harmful pollutants into the air we breathe. Many folks are finding that going back to manual or electric lawn and garden tools is a refreshing change of pace from all of the noise, racket, and smelly exhaust that emanates from gasoline powered tools. Plus, in addition to the green factor, using simple manual tools is also a great way to work in a little bit extra exercise-something we can all use indeed.

Hopefully, these ten tips will help you make your landscaping greener than ever. Just one more thing-once your organic landscape beings to really shine, don’t forget to take plenty of time to be outside and enjoy it!

Author: Home Improvement Advisors

More Than Doubling the Power From a Solar Cell

Stanford’s Nick Melosh, Assistant Professor of Materials Science and Engineering, seems to have cracked the problem of getting the heat of sunlight with the photons working to produce electricity in a solar cell.  That would not be just a photovoltaic; it would be infraredvoltaic plus photovoltaic.  The efficiency gets past 55% and near 60% in some configurations.  This is news.

PETE Solar Cell Test

Melosh says in the Stanford press release, “This is really a conceptual breakthrough, a new energy conversion process, not just a new material or a slightly different tweak. It is actually something fundamentally different about how you can harvest energy.”

“Just demonstrating that the process worked was a big deal,” Melosh said. “And we showed this physical mechanism does exist; it works as advertised.”

Melosh’s group figured out that by coating a piece of semiconducting material with a thin layer of the metal cesium, it made the material able to use both light and heat to generate electricity.  Most silicon solar cells have been rendered inert by the time the temperature reaches 100º C; the “photon enhanced thermionic emission” device doesn’t hit peak efficiency until it is well over 200º C.  “What we’ve demonstrated is a new physical process that is not based on standard photovoltaic mechanisms, but can give you a photovoltaic-like response at very high temperatures,” Melosh said. “In fact, it works better at higher temperatures. The higher the better.”

And the materials needed to build a device to make the process work are cheap and easily available, meaning the power that comes from it will be affordable.

The process is called “photon enhanced thermionic emission,” or PETE and could reduce the costs of solar energy production enough for it to compete with oil as an energy source.  Because PETE performs best at temperatures well in excess of what a rooftop solar panel would reach, the devices will work best in solar concentrators such as parabolic dishes, which can get as hot as 800º C. Dishes are used in large solar farms similar to those proposed for the Mojave Desert in Southern California and usually include a thermal conversion mechanism as part of their design, which offers another opportunity for PETE to help generate electricity as well as minimize costs by meshing with existing technology.  There go all those plans for the huge arrays.  But its OK, getting to 60% efficiency changes the plans in a massive way as well.

Melosh explains how a PETE works, “The light would come in and hit our PETE device first, where we would take advantage of both the incident light and the heat that it produces, and then we would dump the waste heat to their existing thermal conversion systems. So the PETE process has two really big benefits in energy production over normal technology.”

Getting the efficiency up: Photovoltaic systems never get hot enough for their waste heat to be useful in thermal energy conversion, but the high temperatures at which PETE performs are perfect for generating usable high-temperature waste heat. Melosh calculates the PETE process can get to 50 percent efficiency or more under solar concentration, but if combined with a thermal conversion cycle, could reach 55 or even 60% – almost triple the efficiency of existing systems.  These technologies are already understood.

Its still way early – perhaps the paper published online Aug. 1 in Nature Materials is a competitive effort to get on record first.  Using a gallium nitride semiconductor in the “proof of concept” tests, the efficiency achieved in their testing was well below what they have calculated PETE’s potential efficiency to be – which they had anticipated. But the Melosh team used gallium nitride because it was the only material that had shown indications of being able to withstand the high temperature range they were interested in and still have the PETE process occur.  With the right material – most likely a semiconductor such as gallium arsenide, which is used in a host of common household electronics – the actual efficiency of the process could reach up to the 50 or 60 percent the researchers have calculated. They are already exploring other materials that might work.

Another advantage of the PETE system is that by using it in solar concentrators, the amount of semiconductor material needed for a device is quite small.  Melosh explains, “For each device, we are figuring something like a 6-inch wafer of actual material is all that is needed. So the material cost in this is not really an issue for us, unlike the way it is for large solar panels of silicon.”

That answers the questions where the cost of materials has been one of the limiting factors in the development of the solar power industry, so reducing the amount of investment capital needed to build a solar farm is a big advance.

Melosh closes with an academic’s understatement, “The PETE process could really give the feasibility of solar power a big boost. Even if we don’t achieve perfect efficiency, let’s say we give a 10 percent boost to the efficiency of solar conversion, going from 20 percent efficiency to 30 percent, that is still a 50 percent increase overall.”

The Stanford writer hits the competition with oil drum with “And that is still a big enough increase that it could make solar energy competitive with oil” while what they really need to beat is coal.  There is little oil used for power generation while coal is a major fuel source.  Getting competitive with coal would be great, burning coal is still a massive nasty effluent producer, and daylight high output solar would answer peak needs.

Taking the concept further, the PETE idea would be quite a basis to recalculate for orbital solar too.

Melosh and the Stanford team deserve some thanks for the breakout and some encouragement to keep at it.  The working prototype needs built, a bit of demonstration – seeing solar at anything in the 50% plus range is quite a feat, it’s a welcome crack in the efficiency war!

The original post is created by: New Energy and Fuel