Concentrated solar PV is a highly efficient but highly complex form
of cleantech and it has had its share of doubters, mainly due to its
high cost and relatively large footprint. Well, along comes the Obama
Administration to erase your doubts. Yesterday, the Department of Energy
announced a whopping $24 million in funding for technologies leading to
a whole new class of concentrated solar modules that could beat
conventional solar modules on cost and performance, all while
maintaining a slim flat-pack profile.
Concentrated Solar PV Gets Its Moment In The Sun
For those of you new to the topic, concentrated solar PV (CPV, for
concentrated photovoltaic) refers to a system in which a large array of
reflecting surfaces focuses the sun’s rays on a smaller array of solar
cells. That’s not to be confused with concentrating solar power
technology, in which heliostats (that’s fancyspeak for special mirrors)
or trough-shaped structures focus solar energy to heat a liquid, which
is then used to generate steam for a turbine. The US Department of
Energy is already a huge fan of concentrating solar power (for the record, so is Saudi Arabia), and now it’s getting around to concentrated solar PV.
The general idea is to shrink concentrated solar arrays down to a
micro scale, high-performance configuration that has a cost and
footprint similar to a conventional flat solar module. The platform for all this is MOSAIC, a concentrated solar program administered by ARPA-E, the Energy Department’s financing agency for cutting-edge research.
The task is pretty formidable — in order to succeed, you need to herd
thousands of tiny lenses together in a common cause, and you also need
to work around the expensive tracking mechanism used in conventional
concentrated solar systems — but ARPA-E has already assembled 11
concentrated solar projects to tackle the problem, and that’s where the
new $24 million in funding will go.
11 Concentrated Solar Projects
MOSAIC (short for Micro-scale Optimized Solar-cell Arrays with
Integrated Concentration) divides the field into solutions that have the
best potential for two regions of the US, those being the Southwest and
parts of the Northeast and Midwest.
You can get all the details on the concentrated solar projects
from ARPA-E, but for those of you on the go, here’s a quick rundown on
the MOSAIC projects, starting with these three aimed at high direct
sunlight regions:
1. Panasonic Boston Laboratory in Massachusetts is developing micro-tracking systems with rooftop solar applications.
2. Pennsylvania State University is also working on a new tracking
system, something they call Angle Planar Microtracking Microcell CPV.
Here’s the rundown from ARPA-E:
The team will use a combination of
refractive and reflective plastic lenslet arrays to concentrate sunlight
onto a corresponding array of micro – PV cells , which will be transfer
– printed on to a transparent sheet that slides between them. Tracking
will be accomplished by incrementally moving the middle microcell sheet
laterally as the sun shifts, allowing the system to operate throughout
the entire day without tilting the panel.
3. New York State’s University of Rochester has a Planar Light Guide
Concentrated Photovoltaics project in the works, the end result of which
will bee a lightweight module only three millimeters thick, tops. This
project is specifically aimed at providing a solution for urban areas,
where space for rooftop arrays is limited. The following group is focusing on regions that don’t have the advantage of high direct sunlight:
4. The California Institute of Technology–Pasadena is doing something
called Low Direct Normal Incident (DNI) Solar Radiation Technologies,
which deploys quantum dots to take full advantage of relatively low
amounts of sunshine. As with the Rochester project, this one is perfect
for small spaces.
5. Massachusetts Institute of Technology is tasked with a system that
captures both direct and diffused sunlight in module called Integrated
Micro-Optical Concentrator Photovoltaics with Lateral Multijunction
Cells. This will give you an idea of the game-changing efficiencies
ARPA-E expects from MOSAIC:
The team’s micro – optical lens
system will be ultra – compact and highly efficient, quadrupling the
concentration of direct sunlight and tripling and the concentration of
diffuse sunlight. This optics system will act as a prism to split the
solar spectrum into different wavelengths, which will then be collected
by laterally arranged solar cells appropriate to each wavelength.
Conventional PV cells will be integrated benea th this array to capture
diffuse sunlight.
6. A second MIT project, Wafer-Level Integrated Concentrating
Photovoltaics, involves using conventional silicon solar cells to
simplify the needs of the tracking system.
7. Semprius, Inc.
of North Carolina is highlighted in ARPA-E’s press materials for its
Micro-Scale Ultra-High-Efficiency CPV/Diffuse Hybrid Arrays Using
Transfer Printing. The name pretty much says it all.
8. Sharp Laboratories of America
in Washington State has a High-Efficiency Flat Plate PV with Integrated
Micro-PV atop a 1-Sun Panel in the works, featuring a waveguide to add
an extra level of concentration. This system also collects direct
sunlight from the sky, and diffuse sunlight from the ground.
9. Texas A&M University Engineering Experiment Station also takes
the waveguide approach with its Waveguiding Solar Concentrator project:
To significantly increase
concentration of sunlight onto the PV cells, the team will arrange the
concentrating lens arrays in a cascading fashion and align the arrays to
a secondary concentrator using tapered waveguides. The waveguide
concentrators, which are similar in performance to lens or other imaging
optics, will enable the multi-junction solar cells to efficiently
convert diffuse sunlight, enabling the system to be used in less sunny
regions.
Half A Concentrated Solar Loaf Is Better Than None
MOSAIC also includes a third area of interest that involves anything
that could help overcome technological obstacles, even if it addresses
only part of the system: 10. The Palo Alto Research Center in California will deploy
something called a Chiplet Printer, aimed at high-volume printing of
micro-solar cell arrays for concentrated solar systems.
11. Glint Photonics, Inc.
of California, under the Small Business Innovation Research program,
will develop a Stationary Wide-Angle Concentrator PV System that eschews
bulky trackers in favor of a system that involves moving sheets of
receivers within the concentrated solar module. The ultimate goal is a
compact, lightweight system that can be installed on rooftops.
Obama Solar Policy Heating Up
Not for nothing but the new MOSAIC funding announcement comes fast on
the heels of last week’s major shift in energy policy, in which a
federal hydropower marketing agency launched its first ever solar energy buy with many more to come. Add the just-announced federal adoption of PACE solar financing and the new solar incentives
in the recently announced Clean Power Plan, and it seems that the Obama
Administration’s solar policy is cooking with gas, as the saying goes.
Speaking of the Clean Power Plan, just before it was released, we noted that it seemed to be giving natural gas the bum’s rush
in favor of renewables. That’s all the more obvious give the flurry of
federal solar policymaking since the plan was announced earlier this
month. You can also check out Hawaii Governor Ige for another clue as to where US natural gas policy is heading.
http://cleantechnica.com/2015/08/25/concentrated-solar-pv-not-unicorn-sez-energy-dept/
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