US20140360556A1 - Methods and systems for temperature regulation of roof mounted and solar tracker mounted photovoltaic modules - Google Patents

Abstract

One example solar energy system includes a solar tracker, a plurality of photovoltaic modules mounted to the solar tracker, and a temperature regulation system. The PV modules are configured to generate an electrical power output from solar energy incident on the PV modules. The temperature regulation system includes a thermal transfer fluid, a fluid pump operable to pump the thermal transfer fluid, and a plurality of fluid heat exchangers in thermal communication with the plurality of PV modules and in fluid communication with the fluid pump. The fluid heat exchangers are configured to transfer heat from the PV modules to the thermal transfer fluid.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application claims priority to U.S. Patent Application Ser. No. 61/833,262, filed Jun. 10, 2013, which is hereby incorporated by reference in its entirety.
FIELD
• This disclosure generally relates to temperature regulation and processing of thermal energy, and more specifically, to methods and systems for regulating the temperature of roof and/or solar tracker mounted photovoltaic modules and using the energy therefrom.
BACKGROUND
• Various devices can benefit from temperature regulation. In particular, many electronic and/or electrical devices benefit from temperature control or regulation. For example, photovoltaic (PV) modules are devices which convert solar energy into electricity. Some known PV modules convert around 85% of incoming sunlight into heat. During peak conditions, this can result in a heat-generation of 850 W/m²and PV module temperatures as high as 70° C. The electrical power produced by PV modules decreases linearly with increase in module temperature. For example, in bright sunlight, crystalline silicon PV modules may heat up to 20-30° C. above ambient temperature, resulting in a 10-15% reduction in power output relative to the rated power output for the PV module. Moreover, higher PV module temperatures may increase material degradation, such as thermal fatigue failure of interconnections between PV cells in the PV module. Accordingly, PV modules may benefit from reduced temperatures and/or from reducing a rate of increase in temperature.
• This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
BRIEF SUMMARY
• According to one aspect of this disclosure, a solar energy system includes a solar tracker, a plurality of photovoltaic (PV) modules mounted to the solar tracker, and a temperature regulation system. The PV modules are configured to generate an electrical power output from solar energy incident on the PV modules. The temperature regulation system includes a thermal transfer fluid, a fluid pump operable to pump the thermal transfer fluid, and a plurality of fluid heat exchangers in thermal communication with the plurality of PV modules and in fluid communication with the fluid pump. The fluid heat exchangers are configured to transfer heat from the PV modules to the thermal transfer fluid.
• Another aspect of this disclosure is a solar energy system including a plurality of photovoltaic (PV) modules mounted to the roof of a structure, and a temperature regulation system. The PV modules are configured to generate an electrical power output from solar energy incident on the PV modules. The temperature regulation system includes a thermal transfer fluid, a fluid pump operable to pump the thermal transfer fluid, and a plurality of fluid heat exchangers in thermal communication with the plurality of PV modules and in fluid communication with the fluid pump. The fluid heat exchangers are configured to transfer heat from the PV modules to the thermal transfer fluid.
• Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of an example PV module;
• FIG. 2 is a cross-sectional view of the PV module shown inFIG. 1 taken along the line A--A;
• FIG. 3 is a cross-sectional view of a heat exchanger;
• FIG. 4 is a temperature regulation system including the heat exchanger shown inFIG. 3;
• FIG. 5 is a cross-sectional illustration of an assembly including a heat exchanger attached to a PV module;
• FIG. 6 is a top view of an assembly including a heat exchanger integrated into a PV module;
• FIG. 7 is a cross sectional view of the assembly shown inFIG. 6 taken along the line A-A inFIG. 6;
• FIG. 8 is a top view of a stand-alone heat exchanger;
• FIG. 9 is a cross sectional view of heat exchanger shown inFIG. 8 taken along the line B-B inFIG. 8;
• FIG. 10 is a top view of a heat exchanger including a plurality of plastic spacers;
• FIG. 11 is a cross sectional view of heat exchanger shown inFIG. 10 taken along the line C-C inFIG. 10;
• FIG. 12 is a cross sectional view of a connection assembly for use as an inlet and/or outlet for a heat exchanger;
• FIG. 13 is a heat exchanger coupled to a device;
• FIG. 14 is a temperature regulation system including an in-ground secondary heat exchanger;
• FIG. 15 is another temperature regulation system including an in-ground secondary heat exchanger;
• FIG. 16 is a temperature regulation system with a secondary heat exchanger in a body of water;
• FIG. 17 is a temperature regulation system with a secondary heat exchanger to provide hot water;
• FIG. 18 is a temperature regulation system with a secondary heat exchanger to provide hot air;
• FIG. 19 is a temperature regulation system with a PCM based storage and heat exchanger to provide hot water;
• FIG. 20 is a temperature regulation system with a secondary heat exchanger to provide hot water to a hot water storage tank;
• FIG. 21 is a temperature regulation system configured to provide hot water to coils for underfloor heating;
• FIG. 22 is a temperature regulation system with a secondary heat exchanger to provide hot water to a pool;
• FIG. 23 is an assembly of PV modules including heat exchangers;
• FIG. 24 is another exemplary assembly of PV modules including heat exchangers;
• FIG. 25 is an exploded view of the inner and outer layers of an example heat exchanger;
• FIG. 26 is a partial view of the assembled heat exchanger shown inFIG. 25;
• FIG. 27 is a view of the heat exchanger shown inFIG. 25 attached to the bottom surface of a solar panel;
• FIG. 28 is a graph of output power of fixed tilt cooled and uncooled PV modules as a function of the time of day;
• FIG. 29 is a side elevation view of an exemplary system including a PV module and heat exchanger mounted on a solar tracker;
• FIG. 30A is a graph of output power of cooled and uncooled PV modules as a function of the angle of incidence of light on the PV modules;
• FIG. 30B is a graph of short circuit current of cooled and uncooled PV modules as a function of the angle of incidence of light on the PV modules;
• FIG. 30C is a graph of open circuit voltage of cooled and uncooled PV modules as a function of the angle of incidence of light on the PV modules;
• FIG. 30D is a graph of the temperature of cooled and uncooled PV modules as a function of the angle of incidence of light on the PV modules;
• FIG. 31 is a diagram of an example PV module mounted to a roof of a building;
• FIG. 32 is a diagram of a PV module flush mounted on the roof of a building;
• FIG. 33 presents temperature measurements obtained for an uncooled PV module and a cooled PV module installed various distances above a roof;
• FIG. 34 is a temperature regulation system including a roof mounted PV module and heat exchanger; and
• FIG. 35 is a graph of the increase in PV module power output and the increase in water temperature, both as a function of the flow rate of the water through a heat exchanger.
• Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
• The embodiments described herein generally relate to temperature regulation and control. More specifically, embodiments described herein relate to methods and systems for regulating and controlling temperature using a heat exchanger. Specific embodiments are described herein with reference to photovoltaic (PV) modules. However, the teachings of the present disclosure may be applied to any device that may benefit from enhanced temperature regulation. Moreover, although various embodiments will be discussed with respect to cooling a device, it should be understood that the embodiments described herein may additionally, or alternatively, be used to heat a device with which they are used.
• Referring initially toFIGS. 1 and 2, a PV module is indicated generally at100. A perspective view ofPV module100 is shown inFIG. 1.FIG. 2 is a cross sectional view ofPV module100 taken at line A-A shown inFIG. 1.PV module100 includes asolar panel102 and aframe104 circumscribingsolar panel102.
• Solar panel102 includes atop surface106 and a bottom surface108 (shown inFIG. 2).Edges110 extend betweentop surface106 andbottom surface108. In this embodiment,solar panel102 is rectangular shaped. In other embodiments,solar panel102 may have any suitable shape.
• As shown inFIG. 2, thissolar panel102 has a laminate structure that includesseveral layers118.Layers118 may include for example glass layers, non-reflective layers, electrical connection layers, n-type silicon layers, p-type silicon layers, and/or backing layers. In other embodiments,solar panel102 may have more or fewer, including one,layer118, may havedifferent layers118, and/or may have different types of layers.
• As shown inFIG. 1,frame104 circumscribessolar panel102.Frame104 is coupled tosolar panel102, as best seen inFIG. 2.Frame104 assists in protectingedges110 ofsolar panel102. In this embodiment,frame104 is constructed of fourframe members120. In other embodiments frame104 may include more orfewer frame members120.
• Exemplary frame104 includes anouter surface130 spaced apart fromsolar panel102 and aninner surface132 adjacentsolar panel102.Outer surface130 is spaced apart from and substantially parallel toinner surface132. In this embodiment,frame104 is made of aluminum. More particularly, in someembodiments frame104 is made of 6000 series anodized aluminum. In other embodiments,frame104 may be made of any other suitable material providing sufficient rigidity including, for example, rolled or stamped stainless steel, plastic, or carbon fiber.
• FIG. 3 is a simplified cross-sectional view of aheat exchanger300 according to one embodiment of the present disclosure.Heat exchanger300 includes aninner layer302, afluid layer304, and anouter layer306. In this embodiment,fluid layer304 includes achamber305 and one or more spacers or spacing material (not shown inFIG. 3) to maintain a substantially consistent separation between inner andouter layers302 and306. The spacers are connected toinner layer302 andouter layer306 to, among other things, prevent bulging of inner orouter layer302 or306 when fluid is pumped intochamber305 offluid layer304.Seals308 connect inner andouter layers302 and306 to provide a substantially water tight seal aroundfluid layer304, and more specifically aroundchamber305. Thus, a heat transfer fluid, such as water, oil, ethylene glycol, etc., may flow throughfluid layer304 to extract heat from a device with whichheat exchanger300 is used, without the fluid contacting the device. In some embodiments, seals308 may be, additionally or alternatively, spacers or spacing material. Moreover, in some embodiments, seals308 may be integrally formed withinner layer302 and/orouter layer306.
• Inner layer302 is the portion ofheat exchanger300 that will be in contact with the device to be temperature regulated byheat exchanger300. Accordingly,inner layer302 is made from a material having relatively high thermal conductivity, such as aluminum, copper, etc. Moreover, the material forinner layer302 is selected to conform reasonably well to the surface of the device with which it will be used in order to provide sufficient thermal contact or thermal communication with the surface of the device. In this embodiment,inner layer302 comprises a sheet that is suitably made of metal. In other embodiments,inner layer302 may be an aluminum sheet.
• The thickness ofinner layer302 may be varied, e.g., to suit different uses. Thicker sheets may be used to provide increased rigidity and thermal transfer, but with a corresponding decrease in flexibility and/or conformability. In some embodiments,inner layer302 is a thin, metal foil. In one exemplary embodiment,inner layer302 is a metal foil having a thickness of about 0.1 millimeter. In another embodiment,inner layer302 is an aluminum foil having a thickness of about 300 micrometers. Other embodiments may use thicker or thinner metal foils. The use of thinner materials forinner layer302 may increase the flexibility ofheat exchanger300, reduce the weight ofheat exchanger300, and/or permit it to conform to more irregular shaped devices. In general,inner layer302 may be constructed from any thermally conductive material of sufficient strength and impermeability to retain a heat transfer fluid withinheat exchanger300.
• Outer layer306 is the portion ofheat exchanger300 opposite the side ofheat exchanger300 that will be in contact with the device to be temperature regulated by heat exchanger300 (i.e., opposite inner layer302). In some embodiments,outer layer306 is made of a material having relatively high thermal conductivity, such as a metal sheet or a metal foil, to permit heat to radiate fromfluid layer304 throughouter layer306. In other embodiments, outer layer is fabricated from a material that is not particularly thermally conductive, such as a plastic sheet or film. The thickness ofouter layer306 may be varied to suit different uses. Thicker sheets may be used to provide increased rigidity and thermal transfer, but with a corresponding decrease in flexibility and/or conformability. In some embodiments,outer layer306 is a thin, metal foil. In other embodiments,outer layer306 is a thin sheet that is suitably made of plastic. The use of thinner materials forouter layer306 may increase the flexibility ofheat exchanger300, reduce the weight ofheat exchanger300, and/or permit it to conform to more irregular shaped devices. In general,outer layer306 may be made of any material of sufficient strength and impermeability to retain a heat transfer fluid withinheat exchanger300. In one example embodiment,outer layer306 is a transparent acrylic sheet having a thickness of about three millimeters.
• FIG. 4 is a simplified diagram of a closed loop temperature control orregulation system400 including heat exchanger300 (heat exchanger may alternatively be referred to as a meshplate).Heat exchanger300 is coupled to adevice402 that may benefit from temperature regulation provided by heat exchanger. In this embodiment,device402 is a device, such asPV module100, that generates heat andheat exchanger300 is used to reduce the temperature and/or slow the rise in temperature ofdevice402. In other embodiments,heat exchanger300 may be used to increase the temperature ofdevice402 and/or slow the decrease in temperature of device.
• In this embodiment, apump404 pumps a thermal transfer fluid (e.g., a coolant) to an inlet (not shown inFIG. 4) ofheat exchanger300. The transfer fluid passes intochamber305 offluid layer304 through the inlet. Withinchamber305, the thermal transfer fluid draws off heat fromdevice402, via thermal conduction through connection ofinner layer302 todevice402. The thermal transfer fluid exitsheat exchanger300 via an outlet (not shown inFIG. 4) and is directed to a fluid heat exchanger406 (also referred to herein as a secondary heat exchanger). As will be described in more detail below,fluid heat exchanger406 may be any heat exchange device suitable for extracting the heat carried by the thermal transfer fluid. For example, fluid heat exchanger may be a radiator, an extended length of thermally conductive conduit, a condenser, etc. Moreover, in some embodimentsfluid heat exchanger406 may be part of another system, such that heat extracted from thermal transfer fluid may be used by the other system. In one example embodimentfluid heat exchanger406 is a radiator used to warm the air inside a structure. In another embodimentfluid heat exchanger406 is used to heat water.
• As will be readily understood by those of ordinary skill in the art,system400 may, additionally or alternatively, be used toheat device402. In such embodiments, thermal transfer fluid having a temperature greater thandevice402 is pumped bypump404 toheat exchanger300. Withinchamber305, the thermal transfer fluid loses its heat todevice402, via conduction throughinner layer302.Fluid heat exchanger406 then increases the temperature of the heat transfer fluid beforepump404 returns the fluid to heatexchange device300. Asingle system400 may be used to selectively heat orcool device402 through use of a dual purposefluid heat exchanger406 or separate, selectable, fluid heat exchangers406: one for heating the thermal fluid and another for cooling the thermal fluid. Thus,device402 may be cooled bysystem400 when temperatures are relatively high, and warmed bysystem400 when temperatures are relatively cool.
• Acontroller408 controls operation ofsystem400. More specifically,controller408 controls operation ofsystem400 to obtain a desired amount of cooling and/or heating ofdevice402. In some embodiments,controller408 may monitor a temperature ofdevice402 with a sensor (not shown). Other embodiments do not includecontroller408. In this embodiment,controller408 is configured to control operation ofpump404.Controller408 may operate pump404 continuously, intermittently, and/or may pulse pump404 to achieve a desired heating/cooling ofdevice402. In some embodiments,controller408 may additionally, or alternatively, control operation offluid heat exchanger406 and/orheat exchanger300. In still other embodiments,controller408 may also control operation ofdevice402. For example,controller408 may be a PV system controller that controls operation of a direct current (DC) to alternating current (AC) power converter extracting power from aPV module device402.
• In this embodiment,controller408 is configured to operatepump404 other than continuously.Controller408 can operate pump404 at a duty cycle of less than 100% in some embodiments becausesystem400 coolsdevice402 faster than thedevice402 heats up whenpump404 is turned off (i.e., not pumping). In one example,device402 isPV module100 andsystem400 is operable to cool down thePV module100 twice as fast as thePV module100 heats up due to the high heat capacity and low thermal conductivity ofPV module100. In this example,controller408 may operate pump404 with a duty cycle between 30% and 50%. This may provide significant energy gain while reducing pumping costs and coolant usage.
• Controller408 may be any suitable controller, including any suitable analog controller, digital controller, or combination of analog and digital controllers. In some embodiments,controller408 includes a processor (not shown) that executes instructions for software that may be loaded into a memory device. The processor may be a set of one or more processors or may include multiple processor cores, depending on the particular implementation. Further, the processor may be implemented using one or more heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. In another embodiment, the processor may be a homogeneous processor system containing multiple processors of the same type. In some embodiments,controller408 includes a memory device (not shown). As used herein, a memory device is any tangible piece of hardware that is capable of storing information either on a temporary basis and/or a permanent basis. The memory device may be, for example, without limitation, a random access memory and/or any other suitable volatile or non-volatile storage device. The memory device may take various forms depending on the particular implementation, and may contain one or more components or devices. For example, the memory device may be a hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, and/or some combination of the above. The media used by memory device also may be removable. For example, without limitation, a removable hard drive may be used for the memory device.
• FIG. 5 is a cross-sectional illustration of an assembly includingheat exchanger300 attached toPV module100.
• In this embodiment,solar panel102 includes afront glass500,solar cells502 surrounded by anencapsulant504, and aback sheet506. In this embodiment, theencapsulant504 comprises ethylene vinyl acetate (EVA). In other embodiments, any other suitable encapsulant may be used. In this embodiment, backsheet506 is a polyvinyl fluoride (PVF) material. In other embodiments, backsheet506 may be any other suitable back sheet material or a laminate of materials, including, for example a laminate of PVF surrounding a polyester material.
• Thermal transfer fluid entersheat exchanger300 viainlet508 and passes throughchamber305 tooutlet510. Aspacer512 is contained withinchamber305.Spacer512 separates inner andouter layers302 and306 and slows the flow of the thermal transfer fluid throughchamber305 to permit the thermal transfer fluid to absorb heat fromsolar panel102. In this embodiment,spacer512 includes a mesh. More specifically, mesh is a woven-plastic mesh. In other embodiments,spacer512 may include a non-woven mesh, a metal mesh, a sponge, spacer strips, capillary tubes, or some combination of the above. In this embodiment,mesh512 is attached to inner andouter layers302 and306 and substantially fillschamber305. In one exemplary embodiment,mesh512 is approximately 300 micrometers thick.
• Heat exchanger300 may be permanently or semi-permanently integrated intosolar panel102, or may be a standalone component that may be removably attached to a device. Astandalone heat exchanger300 may be coupled todevice402 by any suitable means to provide a thermally connection betweeninner layer302 and a surface ofdevice402. In some embodiments,heat exchanger300 is connected todevice402 using a thermally conductive adhesive, including for example a double-sided, thermally conductive tape.
• FIG. 6 is a top view of anassembly600 includingheat exchanger300 integrated intoPV module100.FIG. 7 is a cross sectional view ofassembly600 taken along the line A-A inFIG. 6.
• Inassembly600,heat exchanger300 is integrally formed withPV module100 and does not need to be separately adhered toPV module100. Moreover,heat exchanger300 uses backsheet506 ofPV module100 asinner layer302. Spacer strips602 extend between inner layer302 (i.e., backsheet506) andouter layer306 to definecavity305. Although not shown inFIGS. 6 and 7,cavity305 also includesspacer512. In this embodiment,spacer512 is ametallic mesh512 capable of withstanding the heat and pressure of lamination withPV module100. In other embodiments,cavity305 may include any other suitable filler and/or spacer.Outer layer306 extends aroundspacer strips602 to adhereheat exchanger300 toPV module100 and facilitate sealingcavity305.
• FIG. 8 is a top view of a stand-alone heat exchanger300 of one embodiment.FIG. 9 is a cross sectional view ofheat exchanger300 taken along the line B-B inFIG. 8. The embodiment ofheat exchanger300 shown inFIGS. 8 and 9 is not integrally formed with any device and may be attached to any device, such asPV module100, by any suitable type of attachment. In this embodiment, two sets ofseals308 are included aroundspacer512.
• FIGS. 10 and 11 show anexample heat exchanger300 in which spacer512 includes a parallel arrangement of plastic spacers.FIG. 10 is a top view, andFIG. 11 is a cross sectional view taken along the line C-C inFIG. 10. The illustratedheat exchanger300 provides a serpentine fluid flow throughheat exchanger300. The serpentine fluid flow provides increased heat transfer as compared to non-serpentine fluid flows.Heat exchanger300 shown inFIGS. 10 and 11 may be integrated into a device or may be astandalone heat exchanger300. The gap between adjacent spacers may be any suitable distance that ensures good fluid flow within the system to improve heat transfer and reduce bloating issues.
• FIGS. 25,26 and27 show anexample heat exchanger300 includingparallel chambers305 through which heat transfer fluid passes.FIG. 25 is an exploded view of the inner andouter layers302 and306.FIG. 26 is a partial view of assembled inner andouter layers302 and306.FIG. 27 is a view of theexample heat exchanger300 attached to thebottom surface108 of asolar panel102. Although three and fourchambers305 are shown inFIGS. 25-27,heat exchanger300 may include any suitable number ofchambers305, whether more or fewer.
• In this embodiment,inner layer302 is a substantially flat sheet,outer layer306 is a corrugated sheet, and bothinner layer302 andouter layer306 are aluminum. Alternatively, inner andouter layers302,306 may be any other suitable thermally conductive material. Moreover,inner layer302 andouter layer306 may be made of different materials.Inner layer302 is attached toouter layer306 byspot welds2500 betweenchambers305. Alternatively or additionally,inner layer302 may be attached toouter layer306 by any suitable connector(s), including rivets, nuts and bolts, adhesives, etc.Heat exchanger300 shown inFIGS. 25-27 may be integrated into a device or may be astandalone heat exchanger300.
• In one example, aheat exchanger300 shown inFIGS. 25-27 was used tocool PV module100 positioned in a fixed position (i.e., without solar tracking). A twenty liter per hour (LPH) flow rate of water fluid throughheat exchanger300 produced a 12% power gain and output water that was 2° C. hotter than the input water. A 2.5 LPH flow produced a 3% power gain inPV module100 and output water that was 11° C. hotter than the input water. Thus, by varying the rate of flow of water, or other thermal transfer fluid, throughheat exchanger300, the amount of cooling (and accordingly, the power gain) and the temperature gain of the water may be varied.FIG. 28 is a graph comparing the maximum power output ofPV module100 with the heat exchanger300 (the “cooled module”) to the maximum power output of anuncooled PV module100 as a function of the time of day.FIG. 35 graphs the increase in power output of thePV module100 and the increase in temperature of the water used for cooling (i.e., outlet temperature minus inlet temperature) both as a function of the flow rate of water through theheat exchanger300.
• FIG. 12 is a partially schematic cross section of asuitable connection assembly1200 for use atinlet508 and/oroutlet510 of any embodiment ofheat exchanger300.Assembly1200 includes amale component1202 positioned insideexchanger300 and extending throughouter layer306. Afemale component1204 is positioned outside ofheat exchanger300 adjacentouter layer306.Female component1204 receives and surrounds the portion ofmale component1202 that extends outside ofheat exchanger300. A portion ofouter layer306 is trapped betweenfemale component1204 andmale component1202.Tubing1206, used to transport thermal transfer fluid to and fromheat exchanger300, is inserted intofemale component1204 tocouple tubing1206 tomale component1202.Assembly1200 forms a liquid tight connection toheat exchanger300. Thermal transfer fluid (e.g., a suitable coolant) may be transferred, viatubing1206 andassembly1200, from outside ofheat exchanger300 to the interior ofheat exchanger300, and vice versa.
• FIG. 13 is a partially schematic view ofheat exchanger300 coupled to adevice1300. The device may be any suitable device that may benefit from temperature regulation provided byheat exchanger300.
• FIGS. 14-22 illustrate various embodiments of closed loop temperature control orregulation system400 includingheat exchanger300. It should be understood that any of the embodiments ofheat exchanger300 described above may be used in thetemperature regulation systems400 shown inFIGS. 14-22. At least some of thetemperature regulation systems400 described herein utilize thermal energy produced by thePV modules100 for other useful purposes and thus are sometimes referred to herein as solar energy systems.
• FIG. 14 is a simplified diagram of atemperature regulation system400 includingheat exchanger300 coupled toPV module100 and an in-groundsecondary heat exchanger1400. Thesecondary heat exchanger1400 is a fluid retaining tank positioned underground. Thesecondary heat exchanger1400 may be made of metal, plastic, or any other suitable material or combination of materials. Fluid from thesecondary heat exchanger1400 is pumped throughheat exchanger300 bypump404. The heated fluid exiting theheat exchanger300 flows back to thesecondary heat exchanger1400. The heat stored in the fluid insecondary heat exchanger1400 is dissipated through thesecondary heat exchange1400 into the ground. The dissipation of heat into the ground occurs particularly at times when the fluid is not being used to cool thePV module100, such as a night. Thesecondary heat exchanger1400 is buried a depth “h” below theground level1402. In some embodiments, h is a depth belowground level1402 at which the annual ground temperature is relatively constant. Alternatively, the depth h may be any other suitable depth. In some embodiments, additives (e.g., charcoal, metal dust, etc.) may be added to the soil surrounding thesecondary heat exchanger1400 to enhance the heat transfer between thesecondary heat exchanger1400 and the ground. In still other embodimentssecondary heat exchanger1400 may be positioned on or above ground level.
• FIG. 15 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and an in-groundsecondary heat exchanger1500. Thesecondary heat exchanger1500 is a serpentine array of tubes positioned underground. Thesecondary heat exchanger1500 may be made of metal, plastic, or any other suitable material or combination of materials. The heated fluid exiting theheat exchanger300 flows through thesecondary heat exchanger1500 before returning to theheat exchanger300. At least some of the heat stored in the fluid is dissipated through thesecondary heat exchange1500 into the ground. Thesecondary heat exchanger1500 is buried a depth “h” below theground level1402. In some embodiments, h is a depth belowground level1402 at which the annual ground temperature is relatively constant. Alternatively, the depth h may be any other suitable depth. In some embodiments, additives may be added to the soil surrounding thesecondary heat exchanger1500 to enhance the heat transfer between thesecondary heat exchanger1500 and the ground. Although shown as a vertical array of tubes,secondary heat exchanger1500 may be a vertical array of tubes, a horizontal array of tubes, an array of coils, an array of vertical and horizontal tubes, an array of arbitrary angled tubes, and/or any suitable combination of horizontal tubes, vertical tubes, arbitrary angled tubes, and coils.
• FIG. 16 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger1600. Thesecondary heat exchanger1600 is a serpentine array of tubes disposed in a body ofwater1602. Thesecondary heat exchanger1600 may be made of metal, plastic, or any other suitable material or combination of materials. The heated fluid exiting theheat exchanger300 flows through thesecondary heat exchanger1600 before being returned bypump404 to theheat exchanger300. At least some of the heat stored in the fluid is dissipated through thesecondary heat exchange1600 into the body ofwater1602. In the illustrated embodiment, the body of water is an open body of water, such as a lake or pond. Alternatively, the body ofwater1602 may be an underground body of water, including a reservoir, an underground lake, an underground river, etc. Although shown as a horizontal array of tubes,secondary heat exchanger1600 may be a vertical array of tubes, a horizontal array of tubes, an array of coils, an array of vertical and horizontal tubes, an array of arbitrary angled tubes, and/or any suitable combination of horizontal tubes, vertical tubes, arbitrary angled tubes, and coils.
• FIG. 17 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger1700. The cooling fluid flows throughheat exchanger300 in a first fluid loop. Thesecondary heat exchanger1700 is configured to transfer at least some of the heat contained in fluid exiting theheat exchanger300 to a secondary fluid loop. In the illustrated embodiment, the secondary fluid loop provides heated water for residential, commercial, industrial, or any other suitable application. More particularly, thesecondary heat exchanger1700 receives the heated fluid from theheat exchanger300 and cooler water from a water supply (not shown). Asecond pump1702 pumps the water tosecondary heat exchanger1700. The heat contained in the fluid exiting theheat exchanger300 is transferred to the water pumped into thesecondary heat exchanger1700. The reduced temperature cooling fluid is returned to theheat exchanger300 bypump404. The heated water exits thesecondary heat exchanger1700 and is delivered for use.
• FIG. 18 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger1800. The cooling fluid flows throughheat exchanger300 in a first fluid loop. Thesecondary heat exchanger1800 is configured to transfer at least some of the heat contained in fluid exiting theheat exchanger300 to a secondary fluid loop. In the illustrated embodiment, the secondary fluid loop provides heated air for residential, commercial, industrial, or any other suitable application. More particularly, thesecondary heat exchanger1800 receives the heated fluid from theheat exchanger300 and a cooler air input. A pump, fan, blower, or other suitable motivator (not shown) forces the cooler air intosecondary heat exchanger1800. The heat contained in the fluid exiting theheat exchanger300 is transferred to the air insecondary heat exchanger1800. The reduced temperature cooling fluid is returned to theheat exchanger300 bypump404. The heated air exits thesecondary heat exchanger1700 and is input to anauxiliary heater1802 to provide additional heat to the air. Alternatively, the heated air exiting thesecondary heat exchanger1800 is delivered for use without heating by anauxiliary heater1802.
• FIG. 19 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger1900. The cooling fluid flows throughheat exchanger300 in a first fluid loop. Thesecondary heat exchanger1900 is a phase change material (PCM) combined heat storage and heat exchanger configured to transfer at least some of the heat contained in fluid exiting theheat exchanger300 to a secondary fluid loop. In the illustrated embodiment, the secondary fluid loop provides heated water for residential, commercial, industrial, or any other suitable application. More particularly, thesecondary heat exchanger1900 receives the heated fluid from theheat exchanger300 and cooler water from a water supply (not shown). Asecond pump1902 pumps the water tosecondary heat exchanger1900. The heat contained in the fluid exiting theheat exchanger300 is transferred, via a phase change material, to the water pumped into thesecondary heat exchanger1900. The reduced temperature cooling fluid is returned to theheat exchanger300 bypump404. The heated water exits thesecondary heat exchanger1900 and is delivered for processing and/or use.
• FIG. 20 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger2000. The cooling fluid flows throughheat exchanger300 in a first fluid loop. Thesecondary heat exchanger2000 is configured to transfer at least some of the heat contained in fluid exiting theheat exchanger300 to a secondary fluid loop. In the illustrated embodiment, the secondary fluid loop provides heated water for residential, commercial, industrial, or any other suitable application. More particularly, thesecondary heat exchanger2000 receives the heated fluid from theheat exchanger300 and cooler water from a water supply (not shown). Asecond pump2002 pumps the water tosecondary heat exchanger2000. The heat contained in the fluid exiting theheat exchanger300 is transferred to the water pumped into thesecondary heat exchanger2000. The reduced temperature cooling fluid is returned to theheat exchanger300 bypump404. The heated water exits thesecondary heat exchanger2000 and is delivered to an insulated hotwater storage tank2004. Thestorage tank2004 includes anauxiliary heater2006 to provide additional heat to the water stored in thestorage tank2004. Alternatively, theauxiliary heater2006 may be omitted. The heated water stored instorage tank2004 is delivered from the hotwater storage tank2004 for processing and/or use. In the illustrated embodiment,pump2002 pumps water fromstorage tank2004 tosecondary heat exchanger2000, while the water supply provide water intostorage tank2004 as needed. Alternatively, water may be provided tosecondary heat exchanger2000 from the water supply directly.
• FIG. 21 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger2100. Thesecondary heat exchanger2100 is an array ofcoils2102 for underfloor heating or in-wall heating. Thecoils2102 are disposed underneath the surface of a floor and/or within the walls (not shown) in a home, office, warehouse, etc. In some embodiments, thecoils2102 are disposed within a floor, such as by being embedded in a concrete foundation. Thesecondary heat exchanger2100 may be made of metal, plastic, or any other suitable material or combination of materials. The heated fluid exiting theheat exchanger300 flows through thesecondary heat exchanger2100 before being returned bypump404 to theheat exchanger300. At least some of the heat stored in the fluid is dissipated through thesecondary heat exchange2100 into the floor and/or through the walls.Secondary heat exchanger2100 may be include a vertical array of tubes, a horizontal array of tubes, an array of coils, an array of vertical and horizontal tubes, an array of arbitrary angled tubes, and/or any suitable combination of horizontal tubes, vertical tubes, arbitrary angled tubes, and coils.
• FIG. 22 is a simplified diagram of anothertemperature regulation system400 includingheat exchanger300 coupled toPV module100 and asecondary heat exchanger2200. The cooling fluid flows throughheat exchanger300 in a first fluid loop. Thesecondary heat exchanger2200 is configured to transfer at least some of the heat contained in fluid exiting theheat exchanger300 to a secondary fluid loop. The secondary fluid loop provides heated water for heating a body of water. In the illustrated embodiment, the body of water is apool2202. Alternatively, the body of water may be a pond, a lake, a tub, or any other body of water that may benefit from heating. Thesecondary heat exchanger2200 receives the heated fluid from theheat exchanger300 and cooler water from thepool2202. Asecond pump2204 pumps the water tosecondary heat exchanger2200. The heat contained in the fluid exiting theheat exchanger300 is transferred to the water pumped into thesecondary heat exchanger2200. The reduced temperature cooling fluid is returned to theheat exchanger300 bypump404. The heated water exits thesecondary heat exchanger2200 and is delivered to thepool2202.
• PV modules100 includingheat exchangers300 may be mounted to any suitable support structure. For example, aPV module100 withheat exchanger300 may be mounted to a ground based rack, a roof (whether directly or via a rack), a solar tracker, etc.
• FIG. 29 is a side elevation view of asystem2900 includingPV module100 and heat exchanger300 (not visible) mounted to asolar tracker2902.Tracker2902 is a horizontal single axis tracker configured to rotate thePV module100 about an axis of rotation (going into the page) atpoint2904. Alternatively, thetracker2902 may be a multi-axis tracker, a single axis tracker rotating about a different axis of rotation, or any other suitable solar tracker. Moreover, although asingle PV module100 is shown inFIG. 29,system2900 may include more than onePV module100.
• Solar trackers (sometimes referred to herein as trackers or tracking devices) are used to alter the position of one ormore PV modules100 mounted to the tracker to attempt to control an angle ofincidence2906 of sunlight on the PV modules. Typically, the desired angle ofincidence2906 is normal (i.e. ninety degrees) to thePV module100. This substantially maximizes the solar energy that is received by thePV modules100 throughout the day. The increased light intensity on the PV module increases the output current of thePV module100, thereby leading to increased power output. The introduction of trackers can boost the output power of a solar power plant by, for example, 10%-35%. The increased light intensity on thePV module100 also increases the temperature of thePV module100.PV modules100 mounted on solar trackers will often be 10° C.-15° C. hotter than asimilar module100 mounted in a fixed position.Heat exchanger300 reduces the temperature of thePV module100 and offsets at least a portion of the increased temperature of thePV module100.
• FIGS. 30A-30D compare the characteristics of an uncooled PV module100 (i.e., without a heat exchanger300) and a cooled PV module100 (i.e., with a heat exchanger300) for various angles of incidence of light on the PV module. In this example, the light was generated using a lamp and the indicated angle of incidence is relative to normal. Thus, at an angle of 0 degrees, thePV module100 faces the lamp directly and receives the most incident light from the lamp.FIG. 30A presents the output power of themodules100 as a function of the angle of incidence.FIGS. 30B and 30C show the short circuit current and the open circuit voltage, respectively, of thePV modules100. The temperature of thePV modules100 is shown as a function of the angle of incidence inFIG. 30D. As can be seen, the cooled module remained significantly cooler than the uncooled module. The cooledmodule100 provided higher open circuit voltages at substantially the same short circuit current as theuncooled module100, thereby generating more output power.
• As mentioned above,PV modules100 may be mounted to a roof of a building. As is well known, a significant amount of heat enters a building through the roof from sunlight shining on the roof. Placing PV modules on a roof shades the portion of the roof under the PV module from the sun, thereby reducing the temperature of the roof and potentially reducing the amount of heat entering the building through the roof.FIG. 31 is a diagram of aPV module100 mounted to aroof3100 of abuilding3102. InFIG. 31,PV module100 is mounted such that it is spaced a distance d from the surface ofroof3100. The distance d is selected to provide clearance to permit air (e.g., wind) to pass between theroof3100 and thePV module100 to facilitate cooling thePV module100. Reducing the distance d reduces the wind loading that thePV module100 applies to theroof3100, at the cost of reduced cooling of the PV module (because less air can flow between thePV module100 and the roof3100). When thePV module100 is flush mounted onroof3100, as shown inFIG. 32, the distance d is reduced substantially to zero and the PV module's contribution to wind loading of theroof3100 is substantially minimized. However, the cooling produced by air passing between thePV module100 and theroof3100 is nearly eliminated. Use ofheat exchanger300 with roof mounted PV modules reduces the temperature of themodule100 without reliance on the airflow between thePV module100 and theroof3100.
• FIG. 33 presents temperature measurements obtained for installation with various distances d (referred to inFIG. 33 as “Height”) for anuncooled PV module100 and a cooled PV module100 (i.e.,PV module100 with heat exchanger300). As can be seen, the temperature of the PV module100 (whether cooled or uncooled) increased as the distance d decreased. The cooledmodule100, however, was significantly cooler than theuncooled module100 at all heights and had a smaller temperature change than theuncooled module100 as the distance d changed. Moreover, when distance d was reduced to zero (i.e., themodules100 were flush mounted), the temperature of the cooledmodule100 was still less than the temperature of the uncooled module at any distance. Similarly, the temperature of the roof under thePV modules100 increased as the distance d decreased. The roof temperature under the cooledPV module100 remained cooler than the roof under theuncooled PV module100 at all distances d. Thus, a cooled PV module100 (i.e., including heat exchanger300) may be installed spaced apart from theroof3100, flush with theroof3100, or anywhere in between to achieve a desired wind loading on theroof3100, reduction in roof temperature, and/or aesthetic appearance of the installed system.
• Moreover, as shown inFIG. 34, a roof mountedPV module100 andheat exchanger300 may be used as part of any of the exampletemperature regulation systems400 described above. The cooling fluid passed through the heat exchanger may be used for additional purposes as described above (for example with respect toFIGS. 17-22). Thus, atemperature regulation system400 may include roof mountedPV modules100 that reduce the temperature of the roof, thereby reducing the temperature in the building and reducing the cost to cool the building. Thesystem400 also provides hot water (or other thermal transfer fluid) that may be used to heat drinking water, heat non-potable water, heat an environment, etc., thereby further reducing electrical usage (and costs) for the building.
• Additionally, a roof mountedPV module100, may be recess mounted into the roof. The amount of recess into the roof may be varied to vary the distance between thetop surface106 of thePV module100 and the surface of the roof. In some embodiments, the PV module may be recessed to position thetop surface106 of thePV module100 level or below the surface of the roof. Recessing thePV module100 into the roof reduces the wind loading on the PV module100 (and thereby reduces the wind loading on the roof). The reduced wind loading may permit fewer structural components to be used to mount thePV module100 to the roof, thereby reducing costs.
• It should be recognized that the temperature regulation systems described above may be combined without departing from the scope of this disclosure. For example, a temperature regulation system may include thesecondary heat exchanger1700 and thesecondary heat exchanger1400. Cooling fluid exiting thesecondary heat exchanger1700 may be delivered tosecondary heat exchanger1400 for further heat dissipation. Moreover, the systems described herein are not limited to the uses described above. For example, systems of this disclosure may be used to provide a low grade energy input to vapor absorption systems for cooling applications. Other uses include a wide range of heating applications in the food product industry, dairies, breweries, distilleries, automobile industry, machine industry, chemical industries, paper and pulp industries, timber processing, etc.
• Although the exemplary embodiments were described above with reference to asingle device402 and/or asingle PV module100, the apparatus, methods, and systems described herein are not so limited. Atemperature regulation system400 may include more than oneheat exchanger300 coupled to one ormore devices402.FIGS. 23 and 24 illustrate two exemplary configurations of such systems. InFIG. 23, thesystem400 includes fourheat exchangers300.PV modules100 are coupled to eachheat exchanger300. The fluid flows through theheat exchangers300 in parallel. Cooling fluid branches off from aninput2300, e.g. the output ofpump404, to provide cooling fluid to eachheat exchanger300. The cooling fluid exiting eachheat exchanger300 is provided to anoutput2302 to be delivered to a secondary heat exchanger. InFIG. 24, the cooling fluid flows through fourheat exchangers300 in series. The cooling fluid output from oneheat exchanger300 is input to thenext heat exchanger300 in the series. The cooling fluid from the last heat exchanger in the series or delivered to a secondary heat exchanger for extraction of the heat in the cooling fluid. The parallel configuration shown inFIG. 23 provides for a greater cooling fluid flow rate than the series configuration shown inFIG. 24. The series configuration ofFIG. 24 provides a higher output temperature for the cooling fluid than the parallel configuration shown inFIG. 23. Moreover, the parallel configuration ofFIG. 23 may provide more even cooling of thePV modules100 than the series connection ofFIG. 24.
• The heat exchangers and systems described herein generally provide inexpensive and effective ways to regulate temperature of a device, such as a PV module. Moreover, the temperature regulation provided by the exemplary heat exchangers and systems may permit PV modules to be mounted without the significant gap typically needed between the back of the PV module and an underlying support (such as a roof) to permit natural convective cooling of the PV module. Such flush mounting of PV modules may decrease wind loading on support structures and reduce installation costs. Moreover, experiments have shown that the temperature of the surface beneath PV modules including the exemplary temperature regulation systems may be lower than the surface beneath a PV module without the exemplary temperature regulation systems. This can reduce conductive and/or convective heating of space below the mounting surface. In roof mounted installations, the space beneath the mounting surface may be the interior of a building. Accordingly, the exemplary systems may facilitate reducing the cooling costs of a building to which PV modules are attached.
• Some embodiments of the heat exchangers disclosed herein can be integrated into the backsheet structure of a PV module using only an encapsulant and can thereby capitalize on existing manufacturing infrastructure and corresponding economy of scale. Some embodiments of the heat exchangers can be used with a simple attachment mechanism to be affixed to nearly any PV modules, thereby making it field-retrofittable and easy to clean and/or replace. These heat exchangers are thus usable to convert a conventional PV system or module into a PV-thermal system.
• Moreover, coolant losses in the exemplary heat exchangers and systems will be negligible in a properly constructed system because coolant is retained within the system, i.e., it is a closed loop system, and there is no provision to allow coolant to intentionally escape. When used to cool PV modules, some heat exchangers of this disclosure have produced a decrease in PV module temperature of 18-20° C., and increased power output of the PV modules by about 10% at peak operating conditions. Other implementations may result in greater or lesser temperature reductions and/or greater or lesser increases in PV module efficiency. Furthermore, some embodiments provide useful dissipation of the heat extracted from a device. For example, the extracted heat may be used to provide heated water, to heat a pool or other body of water or liquid, and/or to heat air.
• When introducing elements of the present invention or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
• As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims (24)

1-20. (canceled)

21. A solar energy system comprising:

a plurality of photovoltaic (PV) modules mounted to the roof of a structure, the PV modules configured to generate an electrical power output from solar energy incident on the PV modules; and

a temperature regulation system comprising:

a thermal transfer fluid;

a fluid pump operable to pump the thermal transfer fluid; and

a plurality of fluid heat exchangers in thermal communication with the plurality of PV modules and in fluid communication with the fluid pump, the fluid heat exchangers configured to transfer heat from the PV modules to the thermal transfer fluid.

22. The solar energy system ofclaim 21, wherein the PV modules are mounted to the roof of the structure spaced a distance from the roof.

23. The solar energy system ofclaim 21, wherein the PV modules are mounted to the roof of the structure with substantially no distance between the PV modules and the roof.

24. The solar energy system ofclaim 21 further comprising a secondary heat exchanger in fluid communication with the fluid pump and the fluid heat exchanger, the secondary heat exchanger configured to dissipate at least some of the heat contained in the thermal transfer fluid.

25. The solar energy system ofclaim 24, wherein the secondary heat exchanger comprises an array of tubes or coils.

26. The solar energy system ofclaim 21, wherein the array of tubes or coils is configured to be buried underground.

27. The solar energy system ofclaim 21, wherein the array of tubes or coils is configured for disposition under a floor to provide underfloor heating.

28. The solar energy system ofclaim 21, wherein the array of tubes or coils is configured for disposition in a body of water.

29. The solar energy system ofclaim 21, wherein the array of tubes or coils is configured for disposition within walls of a structure to provide room heating in the structure.

30. The solar energy system ofclaim 21, wherein the array of tubes or coils is configured for disposition within walls of a structure to provide room heating in the structure.

31. The solar energy system ofclaim 24, wherein the secondary heat exchanger is configured to indirectly dissipate at least some of the heat contained in the thermal transfer fluid to a second fluid.

32. The solar energy system ofclaim 31, wherein the second fluid is air.

33. The solar energy system ofclaim 31, wherein the second fluid is water.

34. The solar energy system ofclaim 33, wherein the secondary heat exchanger is coupled to a water storage tank to provide the water to the water storage tank after dissipating at least some of the heat contained in the thermal transfer fluid to the water.

35. The solar energy system ofclaim 33, wherein the secondary heat exchanger is coupled to a body of water to provide the water to the body of water after dissipating at least some of the heat contained in the thermal transfer fluid to the water.

36. The solar energy system ofclaim 35, wherein the body of water is a pool.

37. The solar energy system ofclaim 31, wherein the secondary heat exchanger comprises a phase change material based heat exchanger.

38. The solar energy system ofclaim 31, wherein the second fluid is ethylene glycol.

39. The solar energy system ofclaim 31, wherein the second fluid is a thermal transfer fluid.

40. The solar energy system ofclaim 21, wherein the PV modules are mounted to the roof of the structure recessed into the roof.

41. The solar energy system ofclaim 22, wherein the PV modules are configured to reduce a temperature of the roof below the PV modules.

42. The solar energy system ofclaim 22, wherein the plurality of PV modules are operable to generate a greater electrical power output than similar PV modules that are not in coupled to the temperature regulation system.

43. The solar energy system ofclaim 22, wherein the temperature regulation system is configured to provide at least some of the heat transferred from the PV modules for use in one of a residential application, a commercial application, and an industrial application.

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