The present invention relates generally to the field of power inverter systems. More particularly, the present invention relates to distributed power system structures, operation and control, and enhanced inverter systems, structures, and processes.
Solar power is a clean renewable energy resource, and is becoming increasingly important for the future of this planet. Energy from the Sun is converted to electrical energy via the photoelectric effect using many photovoltaic cells in a photovoltaic (PV) panel. Power from a PV panel is direct current (DC), while modern utility grids require alternating current (AC) power. The DC power from the PV panel must be converted to AC power, of a suitable quality, and injected into the grid. A solar inverter accomplishes this task.
While solar panels often provide a cost effective and sustainable source of electricity, solar panels need frequent cleaning, up to four times a year, depending on their location and environment. Dirt and dust build-up on the panels prevents sunlight from reaching the silicon, reducing electrical output by up to twenty five percent.
For one prior installation, after a six-month period with no cleaning, a 25 percent increase in electrical output was achieved after washing for one group of solar panels, as compared to a similar neighboring group of panels without cleaning.
While thorough cleaning can increase the output of many solar panel installations, many prior methods and systems do not yield adequate results, or require costly and/or labor intensive operations. High-pressure wash systems often prove to be very ineffective and leave much of the panel dirty, as well as requiring lots of water. Low-pressure water systems, with soft bristle brushes, require thorough manual scrubbing. While a low-pressure system may be very effective, they are typically labor intensive.
Fluid delivery systems and related structures and processes are provided, such as for use with water, treated water, and/or a cleaning solution, for any of cleaning, cooling or any combination thereof, for one or more solar panels in a power generation environment. Enhanced coatings are provided for the incident surface of solar panels, such as to avoid build up of dirt, scale, or other contaminants, and/or to improve cleaning performance. Reclamation, filtration, and reuse structures are preferably provided for the delivered fluid, and seal structures may preferably be implemented between adjoining panels, to minimize loss of the delivered water or cleaning solution.
Enhanced Coated Power Panels.
The efficiency of solar panels falls off rapidly as dirt and other impurities settles on the outer, e.g. upper, surface of the panels. The outer glass substrates 504 (
In some embodiments, the coating materials 508 are described as nano-technology materials, as they provide enhanced cleaning and/or improved light adsorption on any of a macroscopic or microscopic level. For example, the coatings 508 may preferably fill in or reduce voids fissures, and/or scratches 506. As well, the coatings 508 may preferably prevent or reduce buildup of dust, dirt, scale, particulates, and/or other contaminants on the solar panel glass 504.
In some embodiments, the enhanced coatings may preferably comprise hydrophobic coatings 508, e.g. comprising silicon oxide, and/or hydrophilic coatings 508, e.g. comprising titanium oxide.
For example a thin layer, e.g. such as but not limited to about 5,000 Angstroms thick, of a hydrophobic coating 508, provides a surface to which dust and dirt has difficulty adhering. One such hydrophobic coating 508 currently used comprises a Teflon™ based coating 508, wherein incoming water, such as delivered 622,624, or by other means, e.g. rain, condensation, or fog, beads up on the glass 504, such as by reducing the surface contact between the liquid and the glass 504, and allowing the water to roll off, thereby accelerating the cleaning process.
The use of hydrophilic coatings 508, coupled with sunlight and moisture, may preferably react with deposits that land on the glass 504, such as to break down organic material to a point where it blows away in the wind, or washes off with water.
In some exemplary embodiments, the enhanced coatings may preferably comprise hydrophobic coatings 508, e.g. comprising silicon oxide, and/or hydrophilic coatings 508, e.g. comprising titanium oxide.
Other exemplary embodiments of the enhanced coatings 508 comprise both hydrophilic and hydrophobic components, such as to provide a coating material that provides any of reaction with and/or repelling incident water and/or contaminants.
Further exemplary embodiments of the enhanced coatings 508 may preferably comprise a component, e.g. an interference coating 508, that reduces the reflectivity of the glass 504, such as to allow more light to penetrate the glass and strike the solar cell structure 502, to produce more electricity.
Solar panels 10, e.g. such as conventional solar panels may therefore be enhanced by any of a wide variety of coatings 508, such as to repel water, absorb light, and/or break down organic material. Such enhanced coatings 508 may preferably be used for any of reducing dirt buildup on solar panel glass layers 504, reducing cleaning time, and/or increasing the level of cleanliness achievable through cleaning procedures.
Rack Mounting Angles for Solar Panel Arrays Having Fluid Delivery Systems.
Fluid delivery systems 600, e.g. 600a, may preferably provide any of cleaning and/or cooling for one or more solar panels 10, such as by spraying 622 or otherwise distributing 624 water, which may further comprise a cleaner, over the incident surfaces 504 of an array 34 of one or more panels 10.
As seen in
A conventional array of solar panels that are installed flat on a flat roof can theoretically provide 100 percent coverage across the roof, while a conventional array of solar panels that are installed with an eight degree slope on such a roof provides about 90 percent coverage, because of the aisle typically required between racking systems, such as to avoid shading between racks.
Panel arrays that have substantially higher rack angles, e.g. 20 degrees, have a higher front to back height ratio, which typically requires a larger distance between the racking structural rows, thereby resulting in less room for panels, such as for a horizontal roof installation. e.g. about 70 percent coverage for a flat roof system.
In an enhanced power generation system 40 that includes a fluid delivery system 600, such as for cleaning and/or cooling, the rack angle 526 may preferably be chosen for fluid movement 624, e.g. water run off, as well as for power harvest.
For example, one current embodiment of an enhanced power generation system 40 that includes a fluid delivery system 600, installed in Menlo Park, Calif., has a rack mounting angle 526 of about 8 degrees toward the South, which serves to increase power harvest and also allows testing of a fluid delivery system 600.
The specific rack angle 526 for a solar panel installation may preferably be chosen to facilitate self-cleaning during rainfall, automated, i.e. robotic, cleaning 764 (
For example, for the specific solar panels 10 used for the aforementioned installation, and as recommended for many fluid delivery systems 600, a rack angle 526 of at least 10 degrees (toward the South in the Northern hemisphere or toward the North in the Southern hemisphere) may preferably provide greater fluid movement 624, e.g. water run off 624, such as to decrease residual build up of impurities along the surface and lower edges of the solar panels 10.
As the rack mounting angle 526 is increased, such as between 15-20 degrees toward the Equator, fluid runoff 624 is increased, which can promote fluid reclamation and avoid deposition of contaminants at the lower edges of solar panels 10. The increased rack angle 526 also typically allows for a higher total year round harvest of electricity for installations that can accommodate such configurations, since in the winter, the Sun is lower on the horizon, so the additional tilt 526 of the panels 10 allows more light to be harvested. Because the higher slope results in better cleaning there is a trade off between effective cleaning and the concentration of panels on the roof.
The first exemplary embodiment of a fluid delivery system 600a seen in
The exemplary delivery mechanism 602a seen in
The exemplary fluid delivery system 600a seen in
The collection gutter 626 may further comprise a protective screen to prevent leaves or objects other than the water run off 624 from entering the system 600. The collection manifold 628 for the fluid delivery system 600b seen in
While the fluid delivery system 600b is described herein as using spray heads 620 as one example of cleaning and/or cooling, a wide variety of stationary or mobile systems may be used, such as stationary sprays, rotating stationary heads, or even a movable track to spray along the length, e.g. from top to bottom, moving sideways.
As also seen in
In some embodiments 600, the filter 650 preferably removes or reduces levels of minerals, salts, and/or other contaminants from the fluid 606, e.g. water 606, such as depending on available water supplies. In one current embodiment of the fluid delivery system 600, the filter 650 comprises an ELYSATOR 15™ water conditioner, available through International Water Treatment of North America, such as to remove calcium and other minerals from the water 606, before the water 606 is returned to the storage tank 608.
One current embodiment of the storage tank 608 comprises a 300 gallon reservoir filled with tap water 606, which is pumped from the storage reservoir 608 to a four inch PVC water pipe 616 that runs along the length, e.g. 90 feet, of the racked array 34. Every thirty feet, a one inch pipe 644 is tapped off of the four inch pipe 616 through a solenoid operated valve 642. Each of the secondary manifolds 644 feeds three sprinkler heads 620 that wash the panels 10.
The water spray 622 from the spray heads 620 cascades 624 down the panels 10 and into the rain gutter 626, which empties into a collection manifold 628, e.g. a 4-10 inch irrigation pipe. The collected water 624 flows through the collection manifold 628 and through a primary filter, e.g. a leaf filter 630, which filters out large particles. The water is piped down 632 into the storage tank 608, and also is teed to a recirculation pump 646, e.g. a 30 watt pump 646, that feeds the secondary filter 650.
The recirculation pump 646 may preferably continuously circulate the water 606 in and out of the storage tank 608, e.g. through a recirculation line 656, such as for continuous water filtration, i.e. polishing, by the secondary filter 650.
In one current embodiment of the solar power generation system having a fluid delivery system 600b as seen in
This 99 panel test system is divided up into three 33 panel sections, wherein each of the panels have been coated with nano-technology material 508, but were not initially washed, to start to gather dirt, which fell on these panels throughout the day and at night. When dew gathered, the dew wet the dirt, causing it to flow down the panels 10 and catching at the bottom of the panel against the aluminum edge were it sticks because there was not enough water volume in the dew to wash the dirt off the panel.
The installed system therefore provides some minimal washing of the dew itself, on its own, but the dirt gathered at the bottom because there was not sufficient water to completely flush it.
When such dirt settles across the bottom of a panel, such dirt may get thick enough to block out as much as 5 percent of the panel, which causes as much or more than a five percent decrease in power production from the entire string, because on a per panel basis, such an effected panel becomes a weak link.
For solar panel systems that are monitored on a per panel basis, i.e. not on a per cell basis, if the performance of one section of the panel 10, e.g. the lower edge, loses efficiency, e.g. such as by five percent, the efficiency of the entire panel 10 is reduced by five percent.
In the aforementioned system, all 99 panels were monitored, such as for performance testing. On the first 33 panel test section we are going to evaluate the effects of cooling the panels to generate additional electricity output. The cooling was provided by incrementally running water over the panels from early in the morning until late in the afternoon.
In some embodiments of the fluid delivery system 600, such as for installations having solar panels that are enhanced with a protective coating 508, compressed air may be used to blow loose dirt and dust from the panels 10, such as to minimize the use of water 606. As well, water may be used during the evening or at night, e.g. for periodic extra cleaning), such as to minimize evaporation during daylight hours.
The fluid delivery system 600, e.g. such as comprising a robotic watering system 600, is therefore typically installed along the top, i.e. upper end 530a (
In areas where the water contains calcium and other harsh chemicals that may be harmful to the panel, the water treatment 650 may also preferably comprise de-ionization. As well, an additional boost in electrical output may often be gained by cooling the panels 10 during the heat of the day, as the panels decrease output when exposed to higher temperatures.
For example, for the enhanced power generation system shown in
Environmental Effects on Solar System Performance.
For example, especially for panels that are not enhanced with a coating 508 (
The use of a protective coating 508 on the incident surface 532a of the solar panels 10 allows the panels 10 to remain cleaner for a longer period of time, as the enhanced panels are resistant to a build up of dirt and/or scale, such that even before cleaning, the treated panels 10 have a higher electrical output than untreated panels. As well, the enhanced panels are more quickly and more thoroughly cleaned by the fluid delivery system, yielding higher power production for one or more of the solar panels 10.
It is not uncommon, in warm weather, for the panel temperature to rise from about 25 degrees Celsius to about 83 degrees Celsius, as measured on the incident surface 532a of a solar panel 10. This 58 degree rise in temperature, based on an approximate 5 percent of rated output power, results in a total loss of approximately 58 watts on a 200 watt panel, e.g. a loss approaching 30 percent. This estimated loss is based on an absolutely clean panel 10. However, for common situations with a similar 83 degrees Celsius of heat on the panel, in addition to accumulated dirt, such an exemplary solar panel may lose an additional 25-30 watts, resulting in 110 watts of output power for a solar panel 10 that is nominally rated at 200 watts, because of the combined effects of heat and dirt. Therefore, depending on the environment, the fluid delivery system 600 may be used for any of cleaning and/or cooling of the panels 10.
Enhanced Operating Processes for Fluid Delivery Systems Integrated with Solar Panel Systems.
The temperature may preferably be monitored through the temperature sensor (e.g. thermometer, thermocouple, RTD, etc.) on each panel 10, and at the appropriate time and temperature, the system can controllably turn on the water for cooling. As an example, at a high setpoint, e.g. 90 degrees F., the control may trigger the system to turn on, and when the temperature drops to a low setpoint, e.g. 65 degrees F., the cleaning system 600 may preferably turn off.
Solar Array Seal Structures.
As the fluid delivery system 600 is typically installed to provide water for cleaning and/or cooling, and as the water may preferably be recovered, stored and reused, arrays of solar panels 10 may preferably further comprise a sealer structure of sealant 806 at boundaries 804 between solar panels, e.g. such as between the bottom edge of one panels and the upper edge of an adjoining panel, and/or between the sides of adjoining panels 10.
The exemplary seal 806a seen in
Similarly, the exemplary seal 806b seen in
The exemplary seal 806c seen in
The material for the seals 806 may preferably be chosen for the expected temperature range and for other environmental conditions, e.g. exposure to Sunlight. Silicone sealant 608 is often rated for applications up to 300 degrees F.
In contrast to prior cleaning processes, as applied to conventional solar panels in the field, the enhanced cleaning system 600 provides several improvements, such as for one or more solar panels 10, in hardware configurations, and/or in system operation parameters. For example, such an individual panel monitoring system can immediately identify problem areas, such as related to dirt accumulation and/or elevated panel temperatures.
The fluid delivery system 600 and related structures and processes preferably provide several advantages for different environments, such as but not limited to:
Additionally, the algorithms may preferably act to perform optimization to provide any of:
In an earlier installation of conventional solar panels, having a rated capacity of 400 KW, without individual monitoring, several outages resulted in significant loss in power output over extended periods of time. Monitoring of such a 400 KW system can save thousands of dollars in electricity bills as incidences of panel failure, which are conventionally only discovered by manually inspecting the panels.
In the aforementioned system, these outages were caused by, in one case, a panel being hit by a rock, in a second case by a bullet and in two cases, panels that failed, due to hot spots burning through the copper traces. As the system was initially installed without means for monitoring, there was no way of knowing how long these panels were out of commission, but they could have been down for six to eight months before detection. Not only did the system lose the performance of the afflicted panel, but also the weak-link effect brought down the performance of several of the connected strings, exacerbating the problem and loss of electricity.
Accordingly, although the invention has been described in detail with reference to a particular preferred embodiment, persons possessing ordinary skill in the art to which this invention pertains will appreciate that various modifications and enhancements may be made without departing from the spirit and scope of the disclosed exemplary embodiments.
This application is continuation of U.S. patent application Ser. No. 14/938,808, filed Nov. 11, 2015, which is a divisional of U.S. patent application Ser. No. 13/389,951, filed Feb. 10, 2012, which is a U.S. national entry to PCT Patent Application No. PCT/US2010/045352 filed 12 Aug. 2010, and claims priority to U.S. Provisional Application No. 61/234,181, filed 14 Aug. 2009, and is a continuation-in-part of U.S. patent application Ser. No. 12/842,864 filed 23 Jul. 2010, now U.S. Pat. No. 8,035,249.
Number | Name | Date | Kind |
---|---|---|---|
3958171 | Sekino | May 1976 | A |
4488791 | Hinchliffe | Dec 1984 | A |
4599685 | Hombu et al. | Jul 1986 | A |
5706798 | Steinorth | Jan 1998 | A |
5742495 | Barone | Apr 1998 | A |
5982253 | Perrin et al. | Nov 1999 | A |
6153823 | Shiozaki et al. | Nov 2000 | A |
6201180 | Meyer et al. | Mar 2001 | B1 |
6285572 | Onizuka et al. | Sep 2001 | B1 |
6291762 | Jan et al. | Sep 2001 | B1 |
6750391 | Bower et al. | Jun 2004 | B2 |
6810339 | Wills | Oct 2004 | B2 |
7104064 | Hon | Sep 2006 | B2 |
7443052 | Wendt et al. | Oct 2008 | B2 |
7444816 | Hon | Nov 2008 | B2 |
7731383 | Myer | Jun 2010 | B2 |
7772716 | Shaver | Aug 2010 | B2 |
7866927 | Wong | Jan 2011 | B1 |
7994657 | Kimball et al. | Aug 2011 | B2 |
8035249 | Shaver et al. | Oct 2011 | B2 |
9196770 | Newdoll et al. | Nov 2015 | B2 |
20020066473 | Levy et al. | Jun 2002 | A1 |
20020074034 | Fujisaki et al. | Jun 2002 | A1 |
20030111103 | Bower et al. | Jun 2003 | A1 |
20030177706 | Ullman | Sep 2003 | A1 |
20040145188 | Janssen et al. | Jul 2004 | A1 |
20040207366 | Sung | Oct 2004 | A1 |
20040261334 | Liebendorfer et al. | Dec 2004 | A1 |
20050076563 | Faris | Apr 2005 | A1 |
20060103360 | Cutler et al. | May 2006 | A9 |
20060185727 | Matan | Aug 2006 | A1 |
20060266408 | Horne et al. | Nov 2006 | A1 |
20070089778 | Horne et al. | Apr 2007 | A1 |
20070090653 | Martelon | Apr 2007 | A1 |
20070113881 | Mellott | May 2007 | A1 |
20070221267 | Fornage | Sep 2007 | A1 |
20070271006 | Golden et al. | Nov 2007 | A1 |
20080149786 | Bradley | Jun 2008 | A1 |
20080149791 | Bradley | Jun 2008 | A1 |
20080150484 | Kimball et al. | Jun 2008 | A1 |
20080169652 | Green | Jul 2008 | A1 |
20080238195 | Shaver, II et al. | Oct 2008 | A1 |
20090030605 | Breed | Jan 2009 | A1 |
20090040750 | Myer | Feb 2009 | A1 |
20090078299 | Cinnamon et al. | Mar 2009 | A1 |
20090090895 | Hogan, Jr. | Apr 2009 | A1 |
20090146501 | Cyrus | Jun 2009 | A1 |
20090150005 | Hader et al. | Jun 2009 | A1 |
20090160259 | Naiknaware et al. | Jun 2009 | A1 |
20090194669 | Noble et al. | Aug 2009 | A1 |
20090199846 | Collins et al. | Aug 2009 | A1 |
20090266353 | Lee | Oct 2009 | A1 |
20090283129 | Foss | Nov 2009 | A1 |
20090293932 | Augenbraun | Dec 2009 | A1 |
20100043851 | Levy | Feb 2010 | A1 |
20100205870 | Cobb | Aug 2010 | A1 |
20100212093 | Pak | Aug 2010 | A1 |
20100236164 | Chuang | Sep 2010 | A1 |
20100237305 | Miller | Sep 2010 | A1 |
20100270808 | Bates et al. | Oct 2010 | A1 |
20100284737 | McPheeters | Nov 2010 | A1 |
20100296285 | Chemel et al. | Nov 2010 | A1 |
20100328931 | Fogerlie | Dec 2010 | A1 |
20100328932 | Fogerlie | Dec 2010 | A1 |
20110005583 | Thomas | Jan 2011 | A1 |
20110017256 | Stevens | Jan 2011 | A1 |
20110041834 | Liao | Feb 2011 | A1 |
20110058664 | Prax et al. | Mar 2011 | A1 |
20110073161 | Scanlon | Mar 2011 | A1 |
20110085322 | Myer | Apr 2011 | A1 |
20110120523 | Silver | May 2011 | A1 |
20110163222 | Moser | Jul 2011 | A1 |
20110192460 | Tan | Aug 2011 | A1 |
20110259380 | Lai | Oct 2011 | A1 |
20110265840 | Sela | Nov 2011 | A1 |
20120187222 | Galili et al. | Jul 2012 | A1 |
Number | Date | Country |
---|---|---|
2010101396 | Feb 2011 | AU |
201141544 | Oct 2008 | CN |
202362621 | Aug 2012 | CN |
103 20 347 | Dec 2004 | DE |
033706 | Sep 1989 | EP |
S59 79579 | May 1984 | JP |
59-150484 | Aug 1984 | JP |
S62 13084 | Jan 1987 | JP |
9182459 | Jul 1997 | JP |
H10 308523 | Nov 1998 | JP |
3405035 | May 2003 | JP |
2003-197945 | Jul 2003 | JP |
2003-199377 | Jul 2003 | JP |
2009010561 | Jan 2009 | KR |
2005076444 | Aug 2005 | WO |
200622590 | Mar 2006 | WO |
2006078685 | Jul 2006 | WO |
2006071436 | Jul 2006 | WO |
2006130520 | Dec 2006 | WO |
2007106519 | Sep 2007 | WO |
200845335 | Apr 2008 | WO |
200880088 | Jul 2008 | WO |
200888311 | Jul 2008 | WO |
2008125915 | Oct 2008 | WO |
2008129089 | Oct 2008 | WO |
2008144540 | Nov 2008 | WO |
200938810 | Mar 2009 | WO |
2009044982 | Apr 2009 | WO |
2009114730 | Sep 2009 | WO |
201008927 | Jan 2010 | WO |
201050993 | May 2010 | WO |
201068706 | Jun 2010 | WO |
2010102256 | Sep 2010 | WO |
2010118236 | Oct 2010 | WO |
2010118503 | Oct 2010 | WO |
2010123538 | Oct 2010 | WO |
20100123538 | Oct 2010 | WO |
2011044641 | Apr 2011 | WO |
Entry |
---|
Long Island Power Authority Requirements for Interconnection of New Distributed Generation Units with Capacity of 300kVA, Radial Distribution Lines, (Date Unknown—before Jun. 19, 2006), 1-12. |
Solar Tracking System, Solazone, solar tracker, retrieved online on Aug. 19, 2011 from url: http://www.solazone.com.au/tracker.htm, 7 pages. |
Welcome to the next phase of solar, enphase ENERGY Brochure System Overview; retrieved Sep. 13, 2012 online from url: http://enphase.com/producs/microinverters ; copyright 2012, 3 pages. |
Clark, et al., “Plug-n-Play, Reliable Power Systems for Nanosatellites”, 20th Annual AIAAIUSU Conference on Small Satellites retrieved on May 21, 2008 from website http://ssdl.stanford.edu/ssdl/images/storiesIAA236/A06Fall/ARFC/ssc06-vi-2.pdf, Retrieved on May 21, 2008 from website: http://ssdl.stanford.edu/ssdl/images/storiesIAA236/A06Fall/ARFC/ssc06-vi-2.pdf, Aug. 2006, 1-6. |
Orduz, R. et al., “Evaluation Test Results of a New Distributed MPPT Converter”, 22nd European Photovoltaic Solar Energy Conference, Sep. 3-7, 2007, Milan, Italy. |
Santos, J.L. et al., “Maximum Power Point Tracker for PV Systems”, RIO 3—World Climate & Energy Event, Rio de Janiero, Brazil, Dec. 2003, 75-80. |
Ton, D. et al., “Summary Report of the DOE High-Tech Inverter Workshop”, Jan. 2005, 124 pages. |
Walker, G.R et al., “PV String Per-Module Maximum Power Point Enabling Converters;”, Proceedings of the Australasian Universities Power Engineering Conference, Christchurch, New Zealand, Oct. 2003, Total of 6 pages. |
Xantrex Technology, Inc. “PV Series Grid Tie Solar Inverters—Three Phase—North America”, Accessed at: xantrex.comlweb/id/11/p/1/ptl23/product.asp, Feb. 3, 2010, Total of 1 page. |
Number | Date | Country | |
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20170012579 A1 | Jan 2017 | US |
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