Aenert news. Invention analysis
Previously, in a series of articles related to solar energy, we discussed such aspects of the industry as solar energy storage technologies (05.06.2022 and 09.01.2023), solar tracking systems in general (20.06.2022), and single-axis (22.12.2022) and dual-axis tracking systems (27.03.2023) in particular.

Now we will take a glance at experimental and uncommon concentrating solar power inventions that are technically different from conventional and established technologies in this field. We will analyze patents published in the past 20 years and recent patent applications.

Patents and patent applications have been published in 37 patent offices around the world by 636 applicants from 38 countries.

Solar energy. Experimental and unconventional solutions. Cumulative number of patents and applications*, relationship of number of applications to total number of documents by year


*Areas representing patents and applications are overlapping

In the pool of documents collected for this review, the peak values in the number of published patent applications can be seen in 2011-2012 and 2014, which led to a rise in the number of granted patents in 2014-2016. The peak in the number of applications was followed by a moderate decline, so we can expect this trend to continue for patents as well, although the values were above average in recent years. The share of start documents that didn’t belong to any previously formed patent family recently was about 50% on average.

Recently, there was a growth in the number of new IPC subgroups in the collection of patents and patent applications in this field. This can mean that the subject is expanding towards new technological areas, which is natural in the case of unconventional technical solutions. Besides, it should be mentioned that this section of IPC classification has undergone substantial changes in recent years. At the same time, a decline can be seen in the number of new applicants and new patent offices in recent years. All this can indicate a slowdown of patenting activity in this area of concentrating solar power technologies.

The largest number of patents were granted in USPTO (US) during the twenty-year period – more than 25% of the entire collection of patents. It was closely followed by CNIPA (CN) with almost 24%. In the collection of patent applications registered in the past 5 years, CNIPA (CN) was leading with a share exceeding 38%. Rospatent (RU), IP Australia (AU), JPO (JP), and EPO should also be mentioned as the patent offices that granted at least 20 patents each on the subject of interest during the 20-year period.

Solar energy. Experimental and unconventional solutions. Breakdown of inventions by patent offices. Patents, 20 years (left); Applications, 5 years (right)



Residents of the USA were in the lead by the number of patents granted during the 20-year period with a share of almost 34% of all cases. In the pool of patents, high activity was also shown by residents of China, Germany, and Russia. In the case of recent patent applications, the first place was taken by the residents of China with a share of almost 36%, they were followed by the residents of the USA and Germany.

Following is a list of top 10 applicants with the highest Market involvement ratio for patents published in the 20-year period (Market involvement ratio = volume ratio multiplied by ownership ratio, where Volume ratio - share of applicant documents in total number of documents, Ownership ratio - applicant's participation share in total number of documents):

Solar energy. Experimental and unconventional solutions. Top applicants by Market involvement ratio. Patents
 

Of all applicants participating in the reviewed collection of patents, Institute for Electrification of Agriculture (VIESH) (RU) had the largest number of documents – 15. It was followed by University of Arizona (US) – 14, and Mitsui Engineering & Shipbuilding Co., Ltd (JP) – 14. The following applicants were the leaders by the number of documents in the collection of recently published patent applications: Brilliant Light Power Inc (US) – 34, Heliovis AG (AT) – 10, and Nippon Steel Corporation (JP) – 10.

Solar energy. Experimental and unconventional solutions. Top applicants by Market involvement ratio. Applications
 

When considering problems the inventions related to experimental and unconventional solutions in CSP aim to solve, High costs of equipment production comes first in the pool of patents and recent patent applications collected for this analysis. It is followed by Low efficiency of optics or absorber and High costs of repair and replacement in terms of popularity. In the vast majority of cases, technical solutions disclosed in the patent documents under revision were represented in the form of devices. Methods were encountered less often in the documents, while the number of compositions was even smaller. The most popular IPC subgroups assigned to the patent documents were: F24J2/10 (having reflectors as concentrating elements); F24J2/38 (employing tracking means); F24J2/54 (specially adapted for rotary movement); F24J2/46 (Component parts, details or accessories of solar heat collectors); and F24J2/07 (Receivers working at high temperature, e.g. for solar power plants).

The largest patent family in the pool of documents collected for the present analysis includes 37 patent documents and is represented by core document AU2009246639B2 (Core document is a base document for which a complete description of the invention is available in generally-accessible patent databases). It is followed by patent families with core document US20170070180A1 (19 patent documents) and AU2008205056A1 (18 documents):

Method of manufacturing large dish reflectors for a solar concentrator apparatus / P: AU2009246639B2 / IPC: C03B23/025, C03B23/035 / Angel Roger P, Olbert Blain H / Arizona Board of Regents on Behalf of University of Arizona / Appl. date: 08/05/2009; Publ. date: 22/11/2012 / IP Australia / Core document: AU2009246639B2 / Technology categories: CPV, E / Technology elements: O / Problems: HCEP / Technical solution types: M / Claims: 11 / Rating: 14

Photovoltaic power generation systems and methods regarding same / A: US20170070180A1 / IPC: C25B1/04, H01L31/0725, H02S10/10, H02S40/22, H02S40/32, H02S40/38 / Mills Randell L / Brilliant Light Power Inc / Appl. date: 01/04/2014; Publ. date: 09/03/2017 / United States Patent and Trademark Office / Core document: US20170070180A1 / Technology categories: CPV, DS, E, PT / Technology elements: SW / Problems: UP / Technical solution types: C, D, M / Claims: 39 / Rating: 12

Conversion of solar energy to electrical and/or heat energy / A: AU2008205056A1 / IPC: G02B5/10, H01L31/00, H01L31/042 / Horne William E, Morgan Mark D / EDTEK, Inc. / Appl. date: 07/01/2008; Publ. date: 17/07/2008 / IP Australia / Core document: AU2008205056A1 / Technology categories: CPV, E / Technology elements: SW / Problems: HCEP, LEOA / Technical solution types: D / Claims: 42 / Rating: 9

The following abbreviations are used in the documents hereinbefore and hereinafter: C - Composition; D - Device; M - Method; CPV - Concentrator photovoltaics; DS - Dish / Stirling; E - Experimental CSP; H - Solar heating; LFR - Linear Fresnel reflector; PT - Parabolic trough; SH - Storage CSP or Hybrid CSP; ST - Solar tower; UT - Solar updraft tower ; ES - Energy storage; HR - Heat removal; O - Optics; SW - System as a whole; AOP - Administrative and organisational problems; ESI - Environmental and social impact; HCEP - High costs of equipment production; HCM - High costs of maintenance; HCPC - High costs of plant construction; HCRR - High costs of repair and replacement; LEEF - Low efficiency due to environmental factors; LEOA - Low efficiency of optics or absorber; LESE - Low efficiency of secondary equipment; LESM - Low efficiency due to solar movement; UP - Unclear problem.

Solar energy. Experimental and unconventional solutions. Breakdown of documents by family size. Patents and applications



Following are several examples of patent documents with the highest rating calculated using Advanced Energy Technologies methodology, from the collection of documents related to experimental and unconventional solutions in concentrating solar power industry:

Solar energy. Experimental and unconventional solutions. Prominent patent documents by rating:

Thermally controlled solar reflector facet with heat recovery / P: AU2002040652B2 / IPC: F24J2/07, F24J2/08, F24J2/18 / Blackmon James B, Drubka Robert E, Jones Nelson Edwin / Boeing Company, The / Appl. date: 15/05/2002; Publ. date: 19/12/2002 / IP Australia / Core document: AU2002040652B2 / Technology categories: E, ST / Technology elements: HR, O / Problems: ESI, HCEP, HCPC, HCRR, LEEF, LEOA, LESM / Technical solution types: D, M / Claims: 32 / Rating: 20

Thermally controlled solar reflector facet with heat recovery / P: US6911110B2 / IPC: F24J2/07, F24J2/08, F24J2/18, B65C5/0 / BLACKMON JR JAMES B, JONES NELSON EDWIN, DRUBKA ROBERT E / BOEING CO / Appl. date: 12/01/2004; Publ. date: 28/06/2005 / United States Patent and Trademark Office / Core document: AU2002040652B2 / Technology categories: E, ST / Technology elements: HR, O / Problems: ESI, HCEP, HCPC, HCRR, LEEF, LEOA, LESM / Technical solution types: D, M / Claims: 25 / Rating: 19

Broadband reflectors, concentrated solar power systems, and methods of using the same / P: US9523516B2 / IPC: B32B7/02, B32B27/36, G02B1/04, G02B1/10, G02B5/08, G02B6/00, G02B17/00, G02B19/00, F03G6/06, F24J2/00, F24J2/04, F24J2/06, F24J2/10, F24J2/16, F24J2/24, F24J2/38, F24J2/07, F24J2/14, F24J2/54, H01L31/054, B32B15/085, B32B15/08, B32B15/082, B32B15/088, B32B15/09, B32B15/18, B32B15/20, B32B27/08, B32B27/30, B32B27/32, B32B27/34, B32B7/12, B32B27/28, F21V8/00, F24J2/36, H01L31/042 / Hebrink Timothy J, Clear Susannah C, et al. / 3M Innovative Properties Company, Hebrink Timothy J, et al. / Appl. date: 21/12/2009; Publ. date: 20/12/2016 / United States Patent and Trademark Office / Core document: WO2010078105A1 / Technology categories: CPV, E, PT / Technology elements: O / Problems: HCEP, HCRR, LEOA / Technical solution types: D / Claims: 20 / Rating: 18

Capteur solaire (en: Solar collector) / P: MA31249B1 / IPC: F24J2/08, F24J2/07, F24J2/16, F24J2/32, F24J2/38, F24J2/46 / Lin Qinglong / Commissariat A L'energie Atomique / Appl. date: 11/09/2009; Publ. date: 01/03/2010 / Moroccan Industrial and Commercial Property Office / Core document: MA31249B1 / Technology categories: CPV, DS, E, H, LFR, PT, SH, ST, UT / Technology elements: O / Problems: HCEP, HCRR, LEOA / Technical solution types: D / Claims: 18 / Rating: 18

Electrical power systems incorporating thermal energy storage / P: US10326276B2 / IPC: F01K13/00, F01K3/00, F01K3/18, F02C1/05, F03G6/00, F24S10/00, F24S20/20, F24S60/00, F28D20/00, F28D20/02, G05D23/19, H02J15/00, H02J3/28, H02J3/38 / Green Adam / Solarreserve Technology Llc / Appl. date: 05/04/2016; Publ. date: 18/06/2019 / United States Patent and Trademark Office / Core document: US20180083449A1 / Technology categories: E, LFR, PT, ST / Technology elements: ES / Problems: AOP, HCEP, LESE, LESM / Technical solution types: D, M / Claims: 23 / Rating: 18

Trough-stirling concentrated solar power system / P: US6886339B2 / IPC: F03G6/00, F03G6/06, F24J2/06, F24J2/14, F24J2/07, B60K16/00 / Carroll Joseph P, Murphy Terrence H, Frye Patrick E, Otting William D / The Boeing Company (Chicago, IL) [US] / Appl. date: 19/05/2003; Publ. date: 03/05/2005 / United States Patent and Trademark Office / P/A pair: US6886339B2 / Technology categories: DS, E, PT / Technology elements: SW / Problems: HCEP, HCM, HCRR / Technical solution types: D / Claims: 20 / Rating: 18

宽带反射器、集光型太阳能发电系统、以及使用它们的方法 (en: Broadband reflectors, concentrated solar power systems, and methods of using the same) / P: CN102333998B / IPC: F24J2/10, G02B5/08, H01L31/052 / Hebrink Timothy J, Clear Susannah C, et al. / 3M Innovative Properties Company / Appl. date: 21/12/2009; Publ. date: 05/08/2015 / National Intellectual Property Administration / Core document: WO2010078105A1 / Technology categories: CPV, E, PT / Technology elements: O / Problems: HCEP, HCRR, LEOA / Technical solution types: D / Claims: 30 / Rating: 18

In the recent patents and patent applications related to experimental and unconventional solutions in concentrating solar power technologies, the most noticeable groups of documents were those aimed at solving the problems of High costs of equipment production, Low efficiency of optics or absorber, and High costs of repair and replacement. Below we provide several examples of inventions that concern these groups of technical solutions.

- US10724764B2 - the authors propose a solar radiation concentration system having an inflatable concentrating cushion and a set of devices to pivot, retain, and adjust the cushion. The object of the invention is to improve energy conversion efficiency and ensure ease of production and operation;

- US20210058029A1 - reduced manufacturing costs and improved energy production are achieved by a solar-concentrating frustum comprising two material layers with resin deposits allocated between the two layers, means for adjusting the orientation of the frustrum, and a receiver comprising photovoltaic and absorbing fluid sections;

- US20180119993A1 - improved energy transfer and decreased production and management costs are achieved by a non-imaging type concentrator connected to a receiver, both carrying and exchanging solid particles with high solar absorption and low emissivity;

- US20200158378A1 - a double focus solar energy collection system comprising two concentrators in a form of circular Fresnel reflector or rotating paraboloid reflector and a double heat collection vacuumized tube positioned in their focal point. The invention is aimed at improving efficiency, reducing manufacturing costs and protecting the collection tube from external conditions;

- US10197766B2 - a solar collection system comprising a non-airtight enclosure with a light-transmissive surface and pressurizing and filtering means to restrict entry of contaminants. The system is aimed to be less costly and complex, and to improve performance.


High costs of equipment production

Patent US10724764B2 by Heliovis Ag discloses a solar radiation concentration device incorporating an inflatable cushion for concentrating solar radiation onto a receiver. The cushion includes a cover film element with a light-permeable entry window, and a reflector film for solar radiation concentration. The reflector film divides the cushion into at least two hollow spaces and has a curvature when the cushion is inflated. The cushion is operated by a pivoting, retaining, and adjusting devices. The retaining device comprises a lower longitudinal member connected to a bottom film element. The adjusting device for adjusting curvature of the reflector film comprises a tensioning element between the longitudinal member and the reflector film. The tensioning element can change a distance between the longitudinal member and the reflector film. The tensioning element comprises a tensioning film element which is tensioned between the longitudinal member and the reflector film when the cushion is inflated. The tensioning film element comprises a hollow chamber that can be inflated to adjust a distance between the longitudinal member and the reflector film. The claims of the invention further provide detailed description of mutual arrangement and placement of individual elements of the system.

The invention is aimed at improving the efficiency of energy conversion, and providing a system that is easier to produce and operate.

The patent belongs to a family comprising 11 patent documents published between 2016 and 2020 in the EP, WO, AU, CN, MA, and US patent offices.



Image from: US10724764B2

1 - device for concentration of solar radiation; 2 - concentrator cushion; 2' - front end piece; 2" - rear end piece; 7 - pivoting apparatus; 8 - pivoting rings; 10 - suspension apparatus; 11 - support frames; 17 - bottom elements; 26 - covering apparatus; 27 - base element.

Patent application US20210058029A1 published by Hilliard Donald Bennett discloses a solar-concentrating frustum, comprising a first material layer having a reflecting surface, a second material layer disposed concentric to and outside the first layer and "…patterned with a dense array of cone-shaped indentations", and resin deposits positioned at the center of each indentation and contacting the first layer. The solar concentrating system further comprises a rotating assembly providing pivot rotation, a linear bearing assembly providing a tilt motion, and a solar receiver tube having photovoltaic devices and absorbing fluid circulation means to provide electrical power and heated fluid.

The proposed technical solution is aimed at reducing manufacturing costs and improving the efficiency of solar concentrating device.

The invention is a part of a patent family comprising 3 patent documents published between 2015 and 2021 in the US patent office.



Image from: US20210058029A1

62 - central tilt/azimuth axis; 70 - solar concentrator; 73 - optic axis; 80 - frustum structures; 131 - base structure; 227 - demountable tracking assembly; 300 - embodied solar tracking assembly; 400 - base-mount assembly; 401 - spoked wheel assembly; 402 - base-mount hub; 403 - spokes; 405 - base-mount support rim assembly; 410 - base-mount tube; 443 - base-mount utility interconnect region.


Low efficiency of optics or absorber

Patent application US20180119993A1 by King Abdulaziz City for Science & Technology and EZ-Energies GmbH describes a device for collecting solar energy using a non-imaging type concentrator consisting of an inlet area, an outlet area, and an inner space between them. A receiver carrying solid particles is positioned under the concentrator and is fluidly connected to the outlet area. The device collects solar energy by taking a part of these solid particles from the receiver and putting them inside the inner space by such means as an input device, streams of gases or vapors, or a spouted bed. The particles are then returned to the receiver by gravity. The solid particles are made of a material with high solar absorption and low emissivity, for example, oxides of the metallic type. In particular, the authors propose chromite ((Mg,Fe)(Cr,Al)2O4) for this purpose.

The invention proposes improved energy transfer to the receiver, decreased production and management costs, and safe and reliable structure.

The application belongs to a patent family comprising 7 documents published in IT, WO, CA, AU, EP,  and US between 2016 and 2020.



Image from: US20180119993A1

1 - inlet area; 2 - outlet area; 3 - receiver; 4,5 - ray; 6 - input devices; 7,9 - trajectory; 8,10 - solid particle; 11 - solid particles; 12 - CPC concentrator.

A double point focusing solar energy collection apparatus is described in patent application US20200158378A1 filed by Changzhou University. The apparatus includes a primary concentrator, a secondary concentrator, and a heat collection tube. The heat collection tube is located between the two concentrators (circular Fresnel reflector or rotating paraboloid reflector) on their focus points. The heat collection tube of the invention can be of ellipsoidal, spherical, or square shape, and comprises two transparent tubes (outer and inner) made of glass, polymethyl methacrylate (PMMA), or polycarbonate (PC) with vacuum in between the tubes. The inner tube is used to carry energy absorbing medium.

With reference to the drawbacks of prior-art solutions, the authors of the invention mention insufficient optical/photothermal efficiency, erosion of heat collection tube by external conditions, and cost of manufacturing and maintenance.

The patent application belongs to a family consisting of 2 documents published in 2018 and 2020 in the WO and US patent offices.



Image from: US20200158378A1

1 - heat collector; 3 - secondary concentrator; 11 - primary concentrator; 12 - heat collection tube.


High costs of repair and replacement

Patent US10197766B2 discloses a solar radiation collection system comprising a transmissive surface (such as glass, plastic, polyethylene, fiberglass-reinforced plastic, acrylic, and polycarbonate) between an exterior and an interior region of a non-airtight enclosure with a line-focus solar receiver inside. The interior region can be pressurized above an exterior pressure by a pressure source (such as a fan) with a filter to restrict entry of dust and other elements and provide clean pressurized air. A parabolic reflector is suspended from an overhead structure of the enclosure to direct solar radiation passing through the transmissive surface to the receiver. The claims of the invention also describe a method of operation for the system.

With reference to the prior-art solutions, the authors mention that such external factors as dust and sand can affect the efficiency and reliability of the system. The system of the invention is claimed to be less costly and complex.

The patent is a part of a family consisting of 9 patent documents published in WO, EP, CN, and US in 2010-2019.



Image from: US10197766B2

201 - greenhouse; 202 - peak; 203 - gutter; 204 - sidewall; 205 - fan driven overpressure filtration system; 206 - receiver; 207 - pipe; 208 - inlet; 209 - outlet; 210 - solar concentrator; 220 - transparent cover material.

Analysis of these and other inventions in the collection of documents shows that the proposed inventions may include some individual features of conventional technologies, such as parabolic trough or dish-Stirling, but still are unique in many ways. The inventions in this group of documents are generally disclosed in the form of a whole system, describing how concentrated solar power is utilized in each step. However, a substantial portion of solutions also describes a design of a novel optical element or receiver.

More detailed information about inventions in the field of solar energy, and patent research methodology can be found on aenert.com, in SOLAR ENERGY. Solar Trackers. Extended patent report. June 2022, and CONCENTRATED SOLAR POWER. Energy Storage. Patent Database. May 2022.

By the Editorial Board