Skyline Solar
Encyclopedia
Skyline Solar is a Concentrated Photovoltaic (CPV)
company based in Mountain View
, California
. The company has developed medium-concentration photovoltaic systems to produce electricity for commercial, industrial and utility scale solar markets. The company was founded in 2007 by industry veterans Bob MacDonald, Bill Keating and Eric Johnson.
.
The cost of PV energy includes the panel cost, and the cost to install the system. The system installation cost includes racks, wiring, inverters, logistics and simplified installation. Reducing the cost of the PV panel must be coupled with reduced system costs to reach grid parity
where PV electricity matches the cost of grid electricity generation.
The output of the PV system can be increased with improvements in cell efficiency, the use of trackers
, concentration, and other more subtle engineering improvements. Tracking provides up to thirty percent more energy per peak Watt versus fixed tilt systems, and is starting to be implemented on a broader scale. Controlling the temperature of the cell is critical to high energy generation as increased cell temperature decreases the output of the panel. Skyline Solar uses a combination of tracking, cooling fins, and reflectors to focus light on a single strip of silicon cells and maximize energy production.
The reflectors concentrate sunlight onto thin strips of solar cells, reducing the amount of expensive silicon needed and driving down the system's cost. The reflectors are made from durable glass and are very similar to the mirrors used in the Concentrated Solar Power industry.
Panels -- Silicon cells represent the great majority of the cost of any large conventional PV system. Skyline's design replaces most of the silicon with mirrors. Reflectors concentrate sunlight by a factor of 14, and this allows us to use 1/14 as much silicon as flat panel tracking systems and 1/20 as much as non-tracking flat panel. To the panels operating efficiently, Skyline bonds large aluminum cooling fins to the back of each panel. If unfolded, each fin would cover an area more than 40 times larger than the face of the solar panel itself. Natural convection, aided by the wind, keeps the panels operating at temperatures comparable to conventional PV modules.
Reflectors -- Skyline’s X14 Reflectors are highly engineered products. They are near-parabolic in cross-section and their proprietary patent pending shape allows them to focus light uniformly on the solar panels. Uniform flux is important because the presence of over-illuminated and under-illuminated regions would result in lower output. In addition, the Skyline X14 Reflector design enables a tight optical coupling between adjacent arrays which maximizes energy capture regardless of the sun’s location.
Integrated Single Axis Trackers -- The higher the concentrating power of a CPV system, the more precisely it must be aimed. If you’ve ever tried to look at the moon through powerful binoculars you probably noticed you could not hold them steady enough to keep the moon in the center of the image. Because it is a medium concentration system, the Skyline X14 System has a wide acceptance angle
. This is the angle (as seen from the PV system's lens or mirror) between the sun's actual location and the spot in the sky that the concentrator is actually pointing at. Skyline's acceptance angle is 1.3° of azimuth and ± 60° of elevation.
installations towards a more diverse set of applications, different technologies will command advantages in different markets. Two key dimensions determining which technology is best suited are climate and system size. For example, space constrained roof-mount applications in sunny climates are best suited to high efficiency fixed tilt panels whereas roof and ground mount applications in less sunny environments tend to favor thin films which work well in low light conditions.
Thin film
scales well into the tens of Megawatts but efficiency and energy density are much lower than high efficiency silicon. The market for large ground mount systems using silicon continues to evolve quickly, particularly (but not only) in distributed generation
applications where land is valuable. The ability to drive higher energy density and lower energy cost makes tracking important in these areas. For example a large fraction of the PV system capacity installed in Spain in 2008 went into tracked systems and many of the large systems being installed in California, Southwestern US and Southern Europe are now being tracked. Other candidate regions for tracking include North Africa, the Middle East, Australia and parts of Asia.
Concentrating Solar Power (CST, CPV and CPT) has attracted renewed interest for very large, utility scale deployments based on the prospect of low delivered energy cost and storage. If realized, this provides a measure of dispatch-ability, valuable to utilities. Obstacles to CSP include large up front capital investment, very high water consumption and long design and deployment cycles.
Skyline's medium concentration approach combines the best aspects of tracked PV and tracked CSP making it one of the leading solution for sunny climates. Skyline's systems are optimized for 100 kW to multi-Megawatt tracked ground mount applications and are ideal for larger systems.
Skyline Solar, Inc. was a 2008 winner of a Department of Energy
Solar Energy Technology Program grant. The company installed its first system for the San Jose-based Valley Transit Authority (VTA). The VTA System dedication was on May 15, 2009.
Concentrated photovoltaics
Concentrated photovoltaic technology uses optics such as lenses to concentrate a large amount of sunlight onto a small area of solar photovoltaic materials to generate electricity...
company based in Mountain View
Mountain View, California
-Downtown:Mountain View has a pedestrian-friendly downtown centered on Castro Street. The downtown area consists of the seven blocks of Castro Street from the Downtown Mountain View Station transit center in the north to the intersection with El Camino Real in the south...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. The company has developed medium-concentration photovoltaic systems to produce electricity for commercial, industrial and utility scale solar markets. The company was founded in 2007 by industry veterans Bob MacDonald, Bill Keating and Eric Johnson.
Economics of Photovoltaic (PV) Electricity Generation
Photovoltaic panels have been in production since the 1960s. The ramp in solar panel deployment is gated by cost, and the industry is continuously seeking new ways to decrease the cost per kilowatt hour of solar-generated electricity. Simple economies of scale drive the cost down over time as bigger and more automated factories are built and the supply chain develops. At the same time, solar innovation is driving the energy production of PV products up. Local and Federal incentives are being put in place to push the industry towards the size and maturity needed to reach grid parityGrid parity
Grid parity is the point at which alternative means of generating electricity is at least as cheap as grid power.For solar energy, it is achieved first in areas with abundant sun and high costs for electricity such as in California, Hawaii, Spain and Japan. Many solar power advocates predict that...
.
The cost of PV energy includes the panel cost, and the cost to install the system. The system installation cost includes racks, wiring, inverters, logistics and simplified installation. Reducing the cost of the PV panel must be coupled with reduced system costs to reach grid parity
Grid parity
Grid parity is the point at which alternative means of generating electricity is at least as cheap as grid power.For solar energy, it is achieved first in areas with abundant sun and high costs for electricity such as in California, Hawaii, Spain and Japan. Many solar power advocates predict that...
where PV electricity matches the cost of grid electricity generation.
The output of the PV system can be increased with improvements in cell efficiency, the use of trackers
Solar tracker
A solar tracker is a generic term used to describe devices that orient various payloads toward the sun. Payloads can be photovoltaic panels, reflectors, lenses or other optical devices....
, concentration, and other more subtle engineering improvements. Tracking provides up to thirty percent more energy per peak Watt versus fixed tilt systems, and is starting to be implemented on a broader scale. Controlling the temperature of the cell is critical to high energy generation as increased cell temperature decreases the output of the panel. Skyline Solar uses a combination of tracking, cooling fins, and reflectors to focus light on a single strip of silicon cells and maximize energy production.
Technical Details
Skyline Solar’s X14 system combines crystalline silicon arrays with reflectors, single axis trackers, and cooling fins to create a system in which sunlight is concentrated 14 times, hence the name "X14." Integrated trackers adjust the position of the reflectors so that light remains concentrated on the solar cells while the sun travels across the sky. Long rows of arrays are oriented North-South and the tracker rotates east to west to optimize the light capture.The reflectors concentrate sunlight onto thin strips of solar cells, reducing the amount of expensive silicon needed and driving down the system's cost. The reflectors are made from durable glass and are very similar to the mirrors used in the Concentrated Solar Power industry.
Skyline’s Design
The Skyline Solar X14 System consists of three principal components: panels, reflectors and an integrated single-axis tracker. The photograph shows one Skyline X14 Array, which is rated at 3625 DC Watts STC. A typical installation would include as few as 28 or as many as 20,000 arrays installed in many long rows.Panels -- Silicon cells represent the great majority of the cost of any large conventional PV system. Skyline's design replaces most of the silicon with mirrors. Reflectors concentrate sunlight by a factor of 14, and this allows us to use 1/14 as much silicon as flat panel tracking systems and 1/20 as much as non-tracking flat panel. To the panels operating efficiently, Skyline bonds large aluminum cooling fins to the back of each panel. If unfolded, each fin would cover an area more than 40 times larger than the face of the solar panel itself. Natural convection, aided by the wind, keeps the panels operating at temperatures comparable to conventional PV modules.
Reflectors -- Skyline’s X14 Reflectors are highly engineered products. They are near-parabolic in cross-section and their proprietary patent pending shape allows them to focus light uniformly on the solar panels. Uniform flux is important because the presence of over-illuminated and under-illuminated regions would result in lower output. In addition, the Skyline X14 Reflector design enables a tight optical coupling between adjacent arrays which maximizes energy capture regardless of the sun’s location.
Integrated Single Axis Trackers -- The higher the concentrating power of a CPV system, the more precisely it must be aimed. If you’ve ever tried to look at the moon through powerful binoculars you probably noticed you could not hold them steady enough to keep the moon in the center of the image. Because it is a medium concentration system, the Skyline X14 System has a wide acceptance angle
Acceptance angle (solar concentrator)
Acceptance angle is the maximum angle at which incoming sunlight can be captured by a solar concentrator. Its value depends on the concentration of the optic and the refractive index in which the receiver is immersed...
. This is the angle (as seen from the PV system's lens or mirror) between the sun's actual location and the spot in the sky that the concentrator is actually pointing at. Skyline's acceptance angle is 1.3° of azimuth and ± 60° of elevation.
Target PV Markets
As the solar energy market evolves from residential rooftop and off gridOff-the-grid
The term off-the-grid or off-grid refers to living in a self-sufficient manner without reliance on one or more public utilities....
installations towards a more diverse set of applications, different technologies will command advantages in different markets. Two key dimensions determining which technology is best suited are climate and system size. For example, space constrained roof-mount applications in sunny climates are best suited to high efficiency fixed tilt panels whereas roof and ground mount applications in less sunny environments tend to favor thin films which work well in low light conditions.
Thin film
Thin film solar cell
A thin-film solar cell , also called a thin-film photovoltaic cell , is a solar cell that is made by depositing one or more thin layers of photovoltaic material on a substrate...
scales well into the tens of Megawatts but efficiency and energy density are much lower than high efficiency silicon. The market for large ground mount systems using silicon continues to evolve quickly, particularly (but not only) in distributed generation
Distributed generation
Distributed generation, also called on-site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy, generates electricity from many small energy sources....
applications where land is valuable. The ability to drive higher energy density and lower energy cost makes tracking important in these areas. For example a large fraction of the PV system capacity installed in Spain in 2008 went into tracked systems and many of the large systems being installed in California, Southwestern US and Southern Europe are now being tracked. Other candidate regions for tracking include North Africa, the Middle East, Australia and parts of Asia.
Concentrating Solar Power (CST, CPV and CPT) has attracted renewed interest for very large, utility scale deployments based on the prospect of low delivered energy cost and storage. If realized, this provides a measure of dispatch-ability, valuable to utilities. Obstacles to CSP include large up front capital investment, very high water consumption and long design and deployment cycles.
Skyline's medium concentration approach combines the best aspects of tracked PV and tracked CSP making it one of the leading solution for sunny climates. Skyline's systems are optimized for 100 kW to multi-Megawatt tracked ground mount applications and are ideal for larger systems.
Skyline Solar, Inc. was a 2008 winner of a Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
Solar Energy Technology Program grant. The company installed its first system for the San Jose-based Valley Transit Authority (VTA). The VTA System dedication was on May 15, 2009.