Roof mounting bracket for photovoltaic power generation system

Abstract

Multiple brackets are used together to support photovoltaic cells upon a roof. Each bracket includes a mounting rail at an upper side and a bottom rail at a lower side. The bottom rail of one bracket is configured to overlap the mounting rail of another bracket. Lateral joints on each bracket overlap each other to connect adjacent panels of photovoltaic cells. Cell support structures are interposed between the mounting rail and bottom rail to support a photovoltaic stack assembly thereon. Wind clips allow the bottom rail of a higher bracket to be interconnected with a mounting rail of a lower bracket. An undulating end piece allows airflow to enter beneath a lowest bracket and pass up beneath the brackets to provide cooling air for the overall system of photovoltaic cells mounted upon the brackets. Edge flashing precludes water migration laterally at edges of the panels.

1 : A photovoltaic power generation system roof mounting system, comprising in combination:
 at least two photovoltaic elements of substantially planar form;   said photovoltaic elements coupled together and adapted to convert photonic radiation into electric power;   at least two mounting brackets including a higher mounting bracket above a lower mounting bracket, each said mounting bracket adapted to be interposed between at least one photovoltaic element and the roof;   each said mounting bracket having a similar form;   each said mounting bracket having a mounting portion closer to an upper side than to a lower side, said mounting portion adapted to be coupled to the roof in fixed position relative to the roof;   each said mounting bracket having said lower side opposite said upper side;   said lower side of said higher mounting bracket adapted to fit over at least a portion of said lower mounting bracket to define an overlapping portion;   at least one airflow pathway extending beneath said at least two mounting brackets from said lower side of said lower mounting bracket to said upper side of said higher mounting bracket; and   said pathway adapted to cool said photovoltaic elements and said mounting brackets at least partially by natural convection.   
     
     
         2 : The system of  claim 1  wherein said system includes a series of vertically spaced overlapping mounting brackets, with said pathway extending from a lowermost one of said series to an uppermost one of said series, with said pathway being continuous along its entire path. 
     
     
         3 : The system of  claim 2  wherein each said mounting bracket includes ribs on an underside of said bracket, at least one of said ribs extending at least partially horizontally and having at least one passage being formed therein to allow airflow continuously from said lower side to said upper side beneath each said mounting bracket. 
     
     
         4 : The system of  claim 3  wherein said ribs include a plurality of vertical ribs and at least one lateral rib, substantially perpendicular to said vertical ribs, said at least one passage formed in said lateral rib. 
     
     
         5 : The system of  claim 2  wherein said mounting portion includes a mounting rail with a planar surface having holes passing therethrough for receipt of fasteners to secure said mounting rail to the roof, said planar surface of said mounting rail including a perimeter skirt on an uppermost side of said planar surface extending down from said planar surface, said perimeter skirt including at least one gap therein, said gap adapted to allow airflow to pass through said skirt, said gap forming a portion of said at least one airflow pathway. 
     
     
         6 : The system of  claim 2  wherein an end piece is located below a lower side of a lowermost one of said series of mounting brackets, said undulating end piece configured to hold said lower side off of said roof and adapted to allow airflow therethrough. 
     
     
         7 : The system of  claim 6  wherein said end piece is an undulating end piece configured to include repeating troughs and crests which are sufficiently open to allow airflow to enter beneath said bracket by passing through said undulating end piece. 
     
     
         8 : The system of  claim 1  wherein said mounting portion is adjacent said upper side, said mounting portion including a skirt extending down from a top edge of said upper side, said skirt including a plurality of gaps therein, said gaps adapted to allow air circulation therethrough. 
     
     
         9 : The system of  claim 8  wherein each said bracket includes at least one wind clip on an underside of said bracket extending downward and positioned to be located adjacent said roof when said bracket is located adjacent said roof, said wind clips positioned to fit into at least one of said gaps in said skirt of an adjacent mounting bracket, such that said gap in said skirt provides both airflow therethrough and holding of said wind clip of an adjacent said bracket. 
     
     
         10 : The system of  claim 1  wherein at least two photovoltaic elements are assembled together into a single stack of layers with said photovoltaic elements forming one layer in said stack assembly, said stack assembly sized to be approximately twice as wide as one of said mounting brackets and similar in height to a height of a cell support structure of each said bracket, such that two adjacent laterally spaced mounting brackets are similar in size to one of said photovoltaic element stack assemblies for support of said photovoltaic element stack assembly upon said pair of adjacent laterally spaced brackets, said brackets adapted to be coupled together laterally in a manner allowing lateral motion therebetween, such that thermal expansion of said mounting brackets relative to said photovoltaic element stack assembly is accommodated by an expansion joint between said pair of mounting brackets. 
     
     
         11 : The system of  claim 10  wherein each said mounting bracket includes both a vertical expansion joint for vertical thermal expansion between each said mounting bracket and adjacent vertically spaced mounting brackets, and each said mounting bracket includes a lateral joint adapted to move relative to lateral joints of adjacent mounting brackets. 
     
     
         12 : The system of  claim 11  wherein said lateral expansion joint includes each said mounting bracket having one lateral side thereof configured with an over tab and an opposite lateral side of each said mounting bracket configured to include an under tab, said over tab and said under tab adapted to be complementally formed to fit together with said over tab overlying said under tab, and accommodating lateral motion therebetween. 
     
     
         13 : The system of  claim 12  wherein said lateral expansion joint is similar at joints between pairs of brackets underneath a common photovoltaic element stack assembly and at joints between adjacent brackets of different photovoltaic element stack assemblies. 
     
     
         14 : The system of  claim 1  wherein said system includes edge flashing, said edge flashing adapted to overlie lateral edges of said mounting brackets and underlie roof shingles on the roof and lateral to said system. 
     
     
         15 : The system of  claim 14  wherein said edge flashing includes a top plate adapted to overlie a top surface of said mounting bracket and a bottom plate adapted to be located adjacent the roof and beneath the shingles mounted on the roof, with a web joining said top plate with said bottom plate. 
     
     
         16 : The system of  claim 15  wherein said web of said edge flashing between said top plate and said bottom plate taper in height to cause said top plate to be closer to said bottom plate of an upper end of said edge flashing than at a lower end of said edge flashing. 
     
     
         17 : The system of  claim 1  wherein each of said photovoltaic elements is coupled together in series with at least one adjacent photovoltaic element which coupled photovoltaic elements are in turn each coupled to a J-box assembly adapted to be formed within a solid housing to be resistant to moisture, with two leads extending therefrom, one of said leads extending to an adjacent panel of photovoltaic elements on one side with the other lead extending to an adjacent panel of photovoltaic elements on the other side, and with the leads adapted to be coupled to other J-boxes of other photovoltaic element panels or combined as strings of sufficient current and voltage, to combine power from different arrays of photovoltaic element panels. 
     
     
         18 : A method for managing thermal heating of photovoltaic panels, comprising in combination:
 providing at least two photovoltaic elements of substantially planar form; the photovoltaic elements adapted to convert photonic radiation into electric power; at least two mounting brackets including a higher mounting bracket above a lower mounting bracket, the mounting brackets adapted to be interposed between at least one photovoltaic element and the roof; each mounting bracket having a similar form; each mounting bracket having a mounting portion closer to an upper side than to a lower side, the mounting portion adapted to be coupled to the roof in fixed position relative to the roof; each mounting bracket having the lower side opposite the upper side, the lower side of the higher mounting bracket adapted to fit over at least a portion of the adjacent lower one of the at least two mounting brackets to define an overlapping portion;   providing an open pathway extending beneath the at least two mounting brackets from the lower side of the lower mounting bracket to the upper side of the higher mounting bracket;   locating a second similar photovoltaic element at least partially overlapping the first photovoltaic element, the open pathways beneath the elements aligned together to allow natural convection airflow beneath both of the brackets.   
     
     
         19 : The method of  claim 18  including the further step of interlocking adjacent mounting brackets that are adjacent each other but vertically spaced from each other, such that the mounting brackets tend to hold each other down. 
     
     
         20 : The method of  claim 18  wherein said mounting brackets are configured to overlap laterally in a sliding fashion to accommodate thermal expansion across the joint between the laterally overlapping mounting brackets. 
     
     
         21 : The method of  claim 18  including the further step of sealing lateral edges of an array of multiple photovoltaic panels by configuring edge flashing with a top plate adapted to reside above a lateral edge of the photovoltaic panel and a bottom plate adapted to reside above a roof and beneath shingles on the roof, with a web jointing the top plate to the bottom plate. 
     
     
         22 : A bracket for supporting a photovoltaic power generation element upon a roof, the bracket comprising in combination:
 a photovoltaic element support plane on an upper surface of the bracket;   a plurality of vertical ribs extending down from said photovoltaic element support plane and adapted to hold the bracket above an underlying roof surface;   a mounting rail adjacent an upper side of said bracket, said mounting rail adapted to be attached to the roof;   said bracket having a bottom rail on a side of said bracket opposite said mounting rail;   said mounting rail adapted to reside beneath a bottom rail of an adjacent higher similarly formed mounting bracket; and   at least one wind clip coupled to said bracket, said wind clip adapted to fit beneath a mounting rail of an adjacent lower mounting bracket, such that the pair of mounting brackets support each other and wind loads are resisted.   
     
     
         23 : The bracket of  claim 22  wherein said wind clip is a thin elongate structure adapted to be located directly adjacent the roof, said wind clip sized to fit within a gap in a skirt extending down from an upper edge of a planar surface of said mounting rail, said gap in said skirt acting both to allow airflow therethrough and to receive said finger therein. 
     
     
         24 : The bracket of  claim 23  wherein said bracket includes an air circulation pathway beneath said bracket to facilitate natural convection. 
     
     
         25 : The bracket of  claim 24  wherein said bracket includes at least one lateral rib extending substantially perpendicular to said vertical ribs, said lateral rib including at least one passage passing therethrough, such that airflow can occur from a lower end of said bracket to an upper end of said bracket at least partially through said at least one passage. 
     
     
         26 : The bracket of  claim 22  wherein said bracket is adapted to overlap laterally with adjacent photovoltaic element panels to form lateral joints, with said lateral joints configured to fit between adjacent brackets under a common photovoltaic element subassembly, or between adjacent photovoltaic element subassemblies. 
     
     
         27 : The bracket of  claim 26  wherein each photovoltaic element assembly is sized to fit upon two adjacent laterally spaced similar mounting brackets with a lateral joint interposed between said two brackets, said lateral joint adapted to expand and contract laterally due to thermal forces.