Archive for 2013

Dark Solar Process May Change Future – But Not Soon

Sunday, May 26th, 2013

Solar energy is a hot topic these days, with frequent reports of new innovations that drive cost down and efficiency up.  Solar modules are designed to absorb sunlight and convert a portion of the light energy into electric power.  Therefore, one thing a solar module shouldn‘t do is reflect sunlight, because every photon that bounces off is one less electron than can be converted from light to electricity inside a given cell inside the photovoltaic (PV) solar module.

So, one challenge for PV solar module manufacturers has been, how to make that module surfaces less reflective.  Currently this is accomplished on crystalline silicon solar modules through the use of surface treatments that add texture to the silicon surface and non-reflective coatings to the exterior glass surface.  These processes have led to a dramatic decrease in reflectivity from crystalline silicon solar modules over time, such that current products reflect very little light.

One measure of the reflectivity is albedo — the ratio of solar radiation across the visible and invisible light spectrum reflected by a surface. Albedo varies between 0, a surface that reflects no light, and 1, a mirror-like surface that reflects all incoming light.  Solar modules with a single anti-reflective coating have a reflectivity of around 0.1.  By comparison, sand has an albedo between 0.15 and 0.45 and agricultural vegetation (leafy crops, etc.) has an albedo between 0.18 and 0.25.  In other words, solar modules have a lower reflectivity than our area’s prevailing ground cover: vegetation (trees, plants), grass, sand, soil, snow (in wintertime), etc.

Solar modules crafted using thin-film technologies rather than crystalline silicon have historically exhibited lower efficiencies (9-11%) than are available with crystalline silicon (15-17%), thus resulting in lower energy production, making it difficult for them to compete with traditional crystalline silicon-based modules with substantially higher efficiencies.  This, together with other challenges they face in the area of manufacturing processes, have caused thin-film silicon companies to struggle, and many have gone out of business over the last few years (Solyndra, Abound, etc).  However, if thin-film technology could “turn the corner” by reducing the manufacturing complexities and costs they currently face (due to their gas film deposition approach) and could also increase efficiency so that their energy production was comparable to or better than that of crystalline silicon modules, that could lead to new market growth for moNREL-developed technology licensed to Natcore.dules using thin film technology.

One approach that has been experimented with in labs is the use of multiple thin-film layers of silicon, each “tuned” to absorb different wavelengths of light, thus generating more electric power per given amount of solar energy striking the cells.

Another innovation may be coupled with this “tandem” silicon layer approach to decrease reflectivity further and thus increase energy production.  Researchers at the Golden-based National Renewable Energy Laboratory (NREL) have come up with a solution: peppering a solar cell with trillions of tiny holes.  NREL’s black-silicon process uses an acid bath and a small amount of silver nitrate as a catalyst to oxidize the silicon and thus create these nano-holes.

In just three minutes at room temperature, the process can put a trillion microscopic holes in a 6-by-6-inch solar cell.  Each of those tiny holes traps a bit of sunlight, such that only 2 percent of the light is reflected, according to NREL researchers.  That extra light boosts the solar cell’s power.

This “holes” technique, dubbed “dark solar,” has been licensed to Red Bank, N.J.-based Natcore Technology Inc., which plans to combine it with the company’s own low-cost solar-cell-manufacturing process that uses liquid deposition rather than gas deposition.  The combination of these new processes may lead to the successful fabrication of tandem thin-film “dark solar” cells that have lower reflectivity,  higher efficiency, and lower manufacturing costs than are typical today.

“It’s a perfect coupling of technologies,” says Natcore CEO Chuck Provini.  Natcore is a research and development lab, which seeks to marry these various new technologies and fabrication techniques and bring them to the point where they are reproducible at low cost, and thus can be duplicated in a manufacturing production environment.  Then it will seek to license the combined technologies to solar module manufacturers who would produce modules based on the new “dark solar” tandem cells.

Arise Energy’s Take:  The challenge for Natcore will be getting the engineering of the process right…and that will take time.  So, watch for dark solar and tandem cells to potentially emerge in production solar modules sometime within the next decade.  If and when that happens, we will see lower module costs as well as increased performance of the arrays built using these modules.  And that will take us closer to (or beyond) grid parity with PV solar.

Everything Is Energy

Tuesday, February 19th, 2013

Roger Duncan is a well respected expert in the area of energy solutions, and a long-time friend of Michael Kuhn, the man whose company, ImagineSolar, provided us (the founders of Arise Energy) our original NABCEP training before we launched our company.  Michael worked together with Roger Duncan to start the first Photovoltaic Solar incentive program in Texas.  The City of Austin Texas’ solar incentive program for photovoltaic systems was launched in 2004.  Roger worked at Austin Energy at the time (as VP, Distributed Energy Systems).

I want to share Roger’s latest presentation with you.  He was a keynote speaker at the last Texas Renewable Energy Industries Association (TREIA) Conference.  At the conference, he spoke about the future of solar power and introduced the concept of the “unified energy system.”

“The way we use energy, the way we manipulate energy, the way we monitor and move and store energy is changing and it is changing very fast,” says Roger in his presentation.  He then explains that the conventional energy system of the past is one where large centralized fossil-fueled power plants generate electricity and move it in one direction – to buildings.  Also, where our transportation sector runs entirely off petroleum and is completely disconnected from the rest of the system.  As we transform to a unified energy system, we produce power from renewable energy sources as well as fossil fuel.  Buildings not only are more efficient but they are starting to generate their own energy onsite.  The transportation system is moving away from just gasoline to a diversity of fuels and electric power.

This system is interconnected with a smart grid, a bi-directional smart grid that is not only moving information but is moving power back and forth between the points in this system.  The parts of this system are becoming more and more integrated.  The volume and speed of power and information moving between the points of this system is exponentially increasing.   And in order to handle this, we are also exponentially increasing the level of intelligence embedded in the system.  Arise Energy continues to strive to help our clients in Colorado to capitalize on renewable energy solutions, and are excited about the future we see in front of us.  As we continue to implement imbedded computing and imbedded sensors in our home and work environments, we will see more and more automation, and more and more energy savings realized as a result.  Coupled with the implementation of more solar energy solutions, we will build a more sustainable future.  I encourage you to take a few minutes to view Roger’s presentation.  There’s a surprise ending that I won’t give away.

I hope you enjoy the video “Everything is Energy”.   Here’s the link to the video:

Everything Is Energy – Roger Duncan

– Jim Bartlett, Co-Founder & CEO, Arise Energy Solutions

The Impact of PV Solar Solutions on Grid Capacity Requirements

Thursday, February 7th, 2013

While it’s certainly true that photovoltaic (PV) Solar Solutions save their owners thousands of dollars annually over a 30+ year period, and also reduce carbon emissions, there’s another important impact seldom talked about.  This is the impact on Grid Capacity Requirements…specifically the peak capacity that must be provided by local utilities.

Most people just turn on a light switch or the TV without thinking about what’s required to support their usage of electric power.  Any single device – be it a single light bulb, a chest freezer or a large hot-tub – has a specified demand in terms of current required for it to operate at the design voltage (120VAC, or 240VAC).  Small devices such as cell-phone chargers require only tiny amounts of current at 120V, whereas an air conditioning unit or family hot-tub can draw much more power from the grid.  The challenge for utility companies is to figure out how much overall demand for electric power they will experience over the long term and build capacity that will handle the maximum or “peak” demand they may face.  When a utility is unable to supply sufficient capacity to meet the full peak demand at any specific time, the result is often a brown-out, or even a potential black-out due to overloading of the grid.

Thus, electric utilities build their grids so as to produce sufficient power to handle the peak points in demand over time.  But that’s expensive, because the utility essentially needs a network of power plants with the overall capacity to produce energy at that peak level all the time, even if the peak demand only occurs a fraction of the time.  In terms of efficiency of electric energy production, the most efficient grid system would be one where peak capacity is utilized almost 100% of the time, yielding the most energy production and utilization possible from a given set of assets (e.g. power plants).  But in the real world, most electric utilities operate at an average load factor (percentage of total potential capacity) of much less than that:  often just 35-50%.  The gap between potential generation capacity and actual production is essentially wasted capacity…much like empty seats on an airplane that just took off.  The airline could have carried more passengers in those empty seats at almost zero incremental cost.  However, since those empty seats weren’t sold, the plane left the gate, flew its flight plan, and delivered a fewer number of total passengers with less revenue collected, yet at roughly the same costs they would have incurred if they would have booked a full flight.  The situation is similar when it comes to energy production from large generation plants — operating at maximim capacity is always the most efficient.

So, how can a utility company boost its load factor when that’s essentially determined by when consumers decide to turn on their oven, range, hot tub, etc?   A substantial improvement could be achieved in limiting the need for utilities to build larger plants to cover rare peaks in demand, if more electric power consumers were to deploy a combination of energy efficiency (EE) solutions and distributed renewable energy (RE) technologies that would save energy, reduce carbon emissions and assist in balancing the load by time-shifting some of the demand, while offsetting a good portion.  If the use of photovoltaic solar solutions, for example, were more broadly implemented, they would help alleviate some demand, taking demand pressure off of the utility grid and in so- doing, also provide downward pressure on electric utility rates.  Since the production of electric power from solar energy solutions would also take place during daylight hours (in alignment with the period of highest demand for electric power), PV solar installations can make a tremendous impact on net demand that’s required from electric power generation plants…and that can help utilities increase their load factor.  Something to think about.