REFERENCE TO CROSS-RELATED APPLICATION

This application claims priority to Provisional Application Serial No. 61/734,958 filed on December 7, 2012.

FIELD OF THE ART

[0001] Described are methods and systems that include improvements in solar panels and specifically to the application of solar panels as power sources for water pumps.

BACKGROUND

[0002] The efficiency of solar panels at converting light energy from the sun to electrical power degrades as the temperature of operation increases. This reduction is caused by a drop in open-circuit voltage as a result of band-gap reduction in the semiconductor devices that make up the cells of solar panels at high temperature. For crystalline silicon (Si) solar cells, the degradation can be as much as 0.45 percent per degree Celsius (0.45%/°C). For instance, in a solar panel having 15% efficiency at 25°C, a 5°C increase in temperature results in 2.25% degradation, thus reducing efficiency to 12.75%. Thus it is beneficial to maintain the operating temperature of the panel as low as possible to extract the maximum power. For applications such as rural off-grid water-pumping in hot climates, the panels can be subject to ambient temperatures as high as 35-40°C making it important to reduce the temperature of the panels using cooling techniques. [0003] Water pumps in rural environments are used to feed farms and other applications with running water from the ground, lakes or other sources. For water-pumping applications, solar panels can be used to power an electric motor that drives the water pump. Usually water-cooled solar panels have to be driven by an external pump which adds cost. To offset this cost, additional components like heat-pumps, holding tanks, and air-cooling are added to extract more energy, but these additional components also incur additional cost and complexity.

SUMMARY

[0004] Methods and apparatuses described herein are configured to divert a certain amount of pumped water extracted using a water pump to cool the solar panels coupled with the water pump. This is done to deflect or eliminate additional costs, which also increases the lifetime of the panels in hot climates. In at least certain embodiments, the system described includes solar panels, a water cooling circuit to cool the panels and a water bypass line to divert at least some of the pumped water produced at the water pump to cool the solar panels. This water that cools the solar panels becomes heated and can then be used further for warm water utilities or returned to the main flow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] These and other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures, in which: [0006] FIG. 1 depicts an example schematic of the solar panel cooling method using pumped water according to one embodiment.

[0007] FIG. 2 depicts an example of a cooling circuit on a solar panel according to one embodiment.

DETAILED DESCRIPTION

[0008] Throughout the description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. It will be apparent, however, to one skilled in the art that the embodiments described herein may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the various embodiments.

[0009] The techniques described herein are configured to divert a certain amount of pumped water, preferably ground water though other source from lakes or other sources can be used, extracted using a water pump to provide cooling water to cool solar panels coupled with the water pump that are used for its power. This diversion is performed to deflect or eliminate additional costs, which also increases the reliability and lifetime of the panels in hot climates. In at least certain embodiments, the solar panels include (1) a water cooling circuit to cool the panels and (2) a water bypass line to divert at least some of the pumped water produced at the water pump to cool the solar panels. This cooling water becomes heated and can then be used further for warm water utilities or may be returned to the main flow. A particular advantage of this system is that it is preferably a closed system that can operate when other electrical sources such as from the power grid serviced by utilities are not accessible, using battery back-up if required.

[0010] Pumped water from the ground or other sources typically flows through a pipe for domestic or commercial use or into farms for irrigation or consumption. The water pumped from the ground is usually at a much lower temperature than the ambient temperature of the region, and the temperature of other sources of water may in many instances be sufficiently low as well. This pumped water can be partially diverted using a water bypass line that causes the water to be circulated through an existing cooling circuit on the solar panel. In one embodiment, the cooling circuit includes cooling lines built into the back of the solar panels. One advantage of this is that the pump itself can be used to drive the ground or other source water through the cooling lines at the same time it is extracting it for use in farming or other applications.

[0011] FIG. 1 depicts an example schematic of the solar panel cooling method using pumped ground water according to one embodiment. In the illustrated embodiment, cool ground water 120 is extracted using a water pump 130. This water is pumped out of the output of water pump 130 along water line 125. The water in water line 125 can be used for various applications 180 as shown. At least a portion of the ground water 120 output from pump 130 can be diverted into a cooling circuit (see FIG. 2) of solar panel 150 using water bypass line 160. As is well known in the art, when solar panel 150 becomes energized from exposure to sunlight, it is adapted to produce electric power 140 therefrom. This electric power can then be used for a variety of purposes as is well understood in the art.

[0012] FIG. 2 depicts an example of a cooling circuit on a solar panel such as solar panel 150 according to one embodiment. In the illustrated embodiment, cooling circuit 200 is adapted to cool solar panel 150 through contact with the cool ground water 120 that is received from the water bypass line 160 circulating through the circuit. As shown, cooling circuit 200 includes various elements 220 that can be designed to allow the water 120 to flow therethrough. In the illustrated embodiment, the cooling circuit elements 220 are designed to maximize contact with the solar panel 150 so that it dissipates the heat from the panel through thermodynamic induction. Other cooling circuit designs can be used and the embodiments described herein are not limited to any particular design or pattern. For example, the cooling circuit can be disposed within and integral with the solar panel or alternatively can be associated with the solar panel, and constructed so as to attach to a back of the solar panel using some type of attachment mechanism, such as clips, screws, nuts and bolts and the like. The water returned from the panel cooling bypass can either be fed into a utility application 170 where warm water is required or returned back into the main stream.

[0013] The heat dissipation rate and the steady state temperature of the panels can be modulated by changing the flow rate of the pumped water sent to the cooling circuit as cooling water, such as cold ground water, using a control valve in-line with the flow (not shown). In addition, the geometry of the cooling lines on the panel 150 can be adjusted to achieve the desired temperature on the panel. The plumbing connectors between the pump bypass line and the panel cooling circuit are designed to allow the correct flow as well and can include in-line filters to prevent debris from entering the panel cooling circuit. The temperature of the cooling water and the cells inside the panel can be measured independently. In one embodiment, the temperature can be measured using low-cost thermocouples. This data can be used for two purposes: (1) for tracking the changes in panel power output as a function of panel temperature; and (2) for modulating the in-line valve to control the water flow of the cooling water through the cooling circuit. In one embodiment the in-line valve can be modulated such that either the desired temperature on the panel is reached or the temperature difference between the panel and the cooling water is minimized.

[0014] Other embodiments include an additional feature where part of the pumped water or cooling water is pushed as spray water thru a spray-bar along the top edge of each solar panel such that dust and debris can be periodically cleaned off. This is done to keep transmission losses thru the front-glass low. The spray feature can be timed to be toggled by a clock or timer.

[0015] In another embodiment, some of the pumped water, whether from ground water or some other external source, can be supplied to other filtration devices thereby allowing usage for drinking, agricultural and other uses where further purified water is necessary.

[0016] The techniques described herein are not limited to the specific embodiments discussed above. Although particularly described herein with reference to the preferred embodiments thereof, it should be readily apparent to those of ordinary skill in the art that changes and modifications in the form and details may be made without departing from the intended spirit and scope. In addition, these techniques are not limited to any specific type of solar panel. In addition, embodiments may include various operations as set forth above, or fewer or more operations; or operations in an order different from the order described. Also, an embodiment showing a singular component should not be considered limiting; rather, the invention is intended to encompass other embodiments including a plurality of the components, and vice-versa, unless explicitly stated otherwise.