Patent Application
20170173640
Photovoltaic (PV) cells, commonly known as solar cells, are devices for conversion of solar radiation into electrical energy. Generally, solar radiation impinging on the surface of, and entering into, the substrate of a solar cell creates electron and hole pairs in the bulk of the substrate. The electron and hole pairs migrate to p-doped and n-doped regions in the substrate, thereby creating a voltage differential between the doped regions. The doped regions are connected to the conductive regions on the solar cell to direct an electrical current from the cell to an external circuit. When PV cells are combined in an array such as a PV collector, the electrical energy collected from all of the PV cells can be combined in series and parallel arrangements to provide power with a certain voltage and current.
In the field, PV collectors can collect dust, dirt, or other particulates, which can block some amount of solar radiation and ultimately reduce the amount of energy produced by the PV collector.
The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter of the application or uses of such embodiments. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
This specification includes references to “one embodiment” or “an embodiment.” The appearances of the phrases “in one embodiment” or “in an embodiment” do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.
Terminology. The following paragraphs provide definitions and/or context for terms found in this disclosure (including the appended claims):
“Comprising.” This term is open-ended. As used in the appended claims, this term does not foreclose additional structure or steps.
“Configured To.” Various units or components may be described or claimed as “configured to” perform a task or tasks. In such contexts, “configured to” is used to connote structure by indicating that the units/components include structure that performs those task or tasks during operation. As such, the unit/component can be said to be configured to perform the task even when the specified unit/component is not currently operational (e.g., is not on/active). Reciting that a unit/circuit/component is “configured to” perform one or more tasks is expressly intended not to invoke 35 U.S.C. §112, sixth paragraph, for that unit/component.
“First,” “Second,” etc. As used herein, these terms are used as labels for nouns that they precede, and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.). For example, reference to a “first” squeegee element does not necessarily imply that this squeegee element is the first squeegee element in a sequence; instead the term “first” is used to differentiate this squeegee element from another squeegee element (e.g., a “second” squeegee element).
“Based On.” As used herein, this term is used to describe one or more factors that affect a determination. This term does not foreclose additional factors that may affect a determination. That is, a determination may be solely based on those factors or based, at least in part, on those factors. Consider the phrase “determine A based on B.” While B may be a factor that affects the determination of A, such a phrase does not foreclose the determination of A from also being based on C. In other instances, A may be determined based solely on B.
“Coupled”—The following description refers to elements or nodes or features being “coupled” together. As used herein, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically.
“Inhibit”—As used herein, inhibit is used to describe a reducing or minimizing effect. When a component or feature is described as inhibiting an action, motion, or condition it may completely prevent the result or outcome or future state completely. Additionally, “inhibit” can also refer to a reduction or lessening of the outcome, performance, and/or effect which might otherwise occur. Accordingly, when a component, element, or feature is referred to as inhibiting a result or state, it need not completely prevent or eliminate the result or state.
In addition, certain terminology may also be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “side”, “outboard”, and “inboard” describe the orientation and/or location of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import.
In the following description, numerous specific details are set forth, such as specific operations, in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to one skilled in the art that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known techniques are not described in detail in order to not unnecessarily obscure embodiments of the present disclosure.
As described herein, light receiving surfaces of solar collection devices can accumulate dirt, dust, or other particulates (e.g., airborne particulates) that can block light that would otherwise be incident on the collector surface. Such accumulation can reduce the potential power output of the solar collector(s). It can become increasingly challenging to clean PV collectors located in lower temperature environments (e.g., ambient temperatures below 0 degrees Celsius), where, for example, the cleaning solution (e.g., water) used to clean a surface of the PV collector can freeze on the surface and require the removal of the frozen solution before cleaning, which can be difficult to do. The disclosed structures and techniques can offer improved cleaning and reduced cost and energy to perform the cleaning.
The PV robotic cleaning device 110 can include end plates 112. The end plates 112 can be structurally joined by two lateral beams 118. The end plates 112 can be attached to the lateral beams 118 by a clamping mechanical interface that allows the plates to be unclamped and moved along the length of the lateral beams 118. The PV robotic cleaning device 100 can include continuous track mechanisms 116. The distance between the respective continuous track mechanisms 116 can be varied by moving the length of the lateral beams 118 to change the distance between track mechanisms 116. In this way, the robotic cleaning device 110 may be configured to fit a variety of differently sized PV collectors.
The PV robotic cleaning device 110 can include one, or more, cleaning heads 120 for cleaning the collector surface of a solar collector 100. The cleaning head 110 can include one or more components for removing accumulated particulates from the surface 101 of a PV collector 100. The cleaning head 120 can include a dispensing element 130, where first and second squeegee elements 122, 124 can be coupled to the dispensing element 130 as shown. In an example, the dispensing element 130 can be a vapor (e.g., steam) dispensing element. The example cleaning head 120, featuring a dual-squeegee configuration, is discussed in more detail below with respect to
In an embodiment, the cleaning head 120 can be connected to a cleaning solution reservoir 140 through a vaporized cleaning solution supply line 142. In one embodiment, the cleaning solution reservoir 140 can include the vaporized cleaning solution. In an embodiment, the cleaning solution reservoir 140 can be located externally and/or separately from the PV robotic cleaning device 110. In an example, the cleaning solution reservoir 140 can be located on a support vehicle separate from the PV robotic cleaning device 110. In some embodiments, the cleaning solution reservoir 140 can be located within the PV robotic device. In an embodiment, the vaporized cleaning solution supply line 142 can be configured to provide the vaporized cleaning solution from the cleaning solution reservoir 140 to the dispensing element 130. In an example, the vaporized cleaning supply line 142 can connect the cleaning solution reservoir 140 to the dispensing element 130. In one example, the vaporized cleaning supply line 142 can act as a channel to supply vaporized cleaning solution to the dispensing element 130. In some embodiments, the cleaning solution reservoir 140 can include a heater, where the heater can be configured to heat a cleaning solution to form the vaporized cleaning solution. In an example, the cleaning solution reservoir 140 can be heated using propane or diesel (e.g., by burning propane or diesel) to form a vaporized cleaning solution. In some embodiments, the heater may or may not be included with the cleaning solution reservoir 140.
Using a vaporized cleaning solution can offer many advantages over alternative cleaning solutions, such as improved cleaning and reduced amount of cleaning solution and power needed. The difficulty with cleaning with a liquid cleaning solution (e.g., cold, warm, or hot water) in low temperature environments (e.g., below 0 degrees Celsius) is that a sufficient amount of liquid cleaning solution and heat is required to heat the a bulk area (e.g., entire volume) of an object to be cleaned to prevent a surface layer of water from freezing. Cleaning with vapor (e.g., steam) allows to rapidly heat the surface being cleaned to above freezing temperature then remove the condensate before it has had time to be cooled to below freezing (e.g., transition from liquid to solid) from the portion of the object's volume that is still below freezing. For example, a system using heated water to clean a PV module surface, e.g., glass, instead of a vaporized cleaning solution (e.g., steam) may not work well because the heated water will nevertheless freeze because the thermal conductivity of water is lower than glass or it would require a substantial amount of water and power to heat the water to overcome the lower thermal conductivity of water. Similarly, a system using additives, such as methanol, in the cleaning solution can be costly and also require a more complicated system that can recirculate and re-use the cleaning solution.
With reference to
In an embodiment, the cleaning head 220 can include a dispensing element 230. In one embodiment, the cleaning head 220 can have a plurality of squeegee elements 222, 224 and 226. In one example, a first, second and third squeegee elements 222, 224, 226 can be coupled to the dispensing element 230, as shown. In an embodiment, the cleaning head 220 can dispense a vaporized cleaning solution 232. In an embodiment, the first, second and third squeegee elements 222, 224, 226 can inhibit the vaporized cleaning solution 232 from escaping from between the dispensing element 230, and a surface of a PV collector. In an embodiment, the first, second and/or third squeegee elements 222, 224, 226 can be configured to remove a cleaning solution formed (e.g., from the condensate of the vaporized cleaning solution 232) on a surface of the PV collector. In some embodiments, only the second and third squeegee elements 224, 226 can be configured to remove a cleaning solution formed on a surface of the PV collector by the vaporized cleaning solution 232. In an example, a PV robotic cleaning device can drag the first, second and/or third squeegee elements 222, 224, 226 on the PV collector surface to collect the condensate of the vaporized cleaning solution 232 and drag the condensate off an edge of the PV collector.
In an embodiment, the cleaning head 220 can include a brush. In one embodiment, the brush can be configured to remove dirt, dust, and/or other particulates (e.g., airborne particulates) collected on the surface of a PV collector prior to removing the cleaning solution. In an example, the brush can be applied before the condensate has time to freeze. In an embodiment, the first, second and/or third squeegee elements 222, 224, 226 can be configured to remove a cleaning solution formed on a surface of the PV collector after applying the brush on the surface of the PV collector. In an embodiment, the vaporized cleaning solution 232 can be applied to the brush to heat the brush and/or prevent condensate from freezing on the brush.
Turning now to
In an embodiment, the PV robotic cleaning device 410 is substantially similar to the PV robotic cleaning device 110 of
Referring to
Referring to
In an embodiment, applying a vaporized cleaning solution 432 can heat a portion 406 of the PV collector 400, where the heat can allow a cleaning solution to condense from the vaporized cleaning solution 432 on the portion 406 of the PV collector. In an example, use of the vaporized cleaning solution 132 can inhibit the cleaning solution (e.g., condensate from the vaporized cleaning solution 432) from freezing on the portion 406 of the PV module 400. In one example, the vaporized cleaning solution 432 can be applied at a temperature approximately greater than 100 degrees Celsius. In one example, as shown, before applying the vaporized cleaning solution 432, the portion 406 can be at a first temperature. In an example, the first temperature can be in a range of approximately −15 to 0 degrees Celsius. In an example, applying the vaporized cleaning solution 432 can heat the portion 406 to a second temperature, where the second temperature can be greater than approximately 0 degrees Celsius. After the cleaning, other portions, 402, 404 of the PV collector can return to an ambient temperature. In an example, the portions 402, 404 already cleaned by the PV robotic cleaning device can return to a temperature below 0 degrees Celsius. In one example, the ambient temperature while applying can be in a range of −15 to 0 degrees Celsius. In an embodiment, the vaporized cleaning solution 432 can be steam. In an example, the cleaning solution (e.g., condensate of the vaporized cleaning solution 432) can be water. As shown, applying a vaporized cleaning solution 432 allows for only a portion of the PV collector (e.g., 406) to be heated without having to heat the entire PV collector. In an example, heating only a portion of the PV collector can save energy, reduce costs, and clean the PV collector better in comparison to other methods, such as using heated water.
In an embodiment, the cleaning head can include first and second squeegee elements 422, 424. In an example, the first and second squeegee elements 422, 424 can inhibit the vaporized cleaning solution 432 from escaping from between the dispensing element 430, and the surface 401 during the application. However, in other embodiments, PV robotic cleaning device 110 can include a one, or more than two squeegee configuration.
Referring to
Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even where only a single embodiment is described with respect to a particular feature. Examples of features provided in the disclosure are intended to be illustrative rather than restrictive unless stated otherwise. The above description is intended to cover such alternatives, modifications, and equivalents as would be apparent to a person skilled in the art having the benefit of this disclosure.
The scope of the present disclosure includes any feature or combination of features disclosed herein (either explicitly or implicitly), or any generalization thereof, whether or not it mitigates any or all of the problems addressed herein. Accordingly, new claims may be formulated during prosecution of this application (or an application claiming priority thereto) to any such combination of features. In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims and features from respective independent claims may be combined in any appropriate manner and not merely in the specific combinations enumerated in the appended claims.
