Investigating an Effective Cooling Strategy to Minimize Water Consumption

My research project had begun all the way back in the summer of 2019, the world was in quarantine and I was itching to learn something new. From previous years I had done some research involving water filtration and was thinking of conducting new research for another type of renewable energy, as it is something that I was passionate about. A few weeks went by and I got in contact with my mentor, and discussion had begun of what I had wanted to do. My mentor had given me some ideas on something to deal with Solar Panels, and that's when I had begun to start research in ways to make a solar panel more valuable with its energy production. This led me to do research and test in water delivery, different types of nozzles to splash water, the layout of this manifold system to deliver water, and even the basics of how a solar panel works. As I had begun to work on this project I loved I realized my skills in presentations, Excel, poster-making, and design were growing even more. I believe not only did I learn from my project knowledge-wise, but I also matured with understanding all the elements that go into a research project, which has led me here!

Rationale: This project is important because it uses solar energy, and the usage of solar panels will help with electricity power plants. Solar energy is a renewable resource that has started to reduce the load of fossil fuels being required, so this project helps to bring on the benefits of installing solar panels to your house in order to reduce the amount of electricity that comes from fossil fuels, and maximize the amounts of power you could produce in your own backyard. This project also helps with the labor that electricity grids, and keeps the electricity in the grid balance. This allows for an on-demand of a 10% to 15% boost of PV plant output.

Intro:

Solar Panels work to convert light from the sun, which are particles of energy called photons into electricity. As the time of the day changes, the power produced by the sun will change directly to the pattern of the sun because at some point of the day not all of the sun’s photons will reach the panel. A pattern of the sun generated by the solar panel throughout a full day of the sun being out is called a bell curve.

The temperature has an environmental impact on the output of the solar panels of energy because the temperature relates to power. If the temperature of the panel were to decrease, the power would increase, and if the temperature were to increase, power would decrease. This is because heat reduces the output efficiency. And taking into consideration that if a panel were to have a high temperature, the solar panel’s measured temperature coefficient which is just the percent change in power output over a change of temperature, for every 1°C above 45°C the efficiency will decrease 0.44%, by using multiple thermocouples across the backside of a solar panel, measurements of a solar panel's temperature are able to be collected throughout the day.

So in order to find an overall effective way to cool solar panels to maximize the power output of a solar panel at solar noon, a cooling system must be installed in order to cause an even distribution of cooling throughout the area of the panel, which will decrease the overall temperature of a solar panel and increase the power output.

Development of Manifold:

The manifold is an arrangement of spray bars and nozzles, and it is the delivery device that I had built in order to automatically splash water to the back of the solar panel. The manifold has spray bars that alternate between a 7 nozzle and 6 nozzle spray bar from positions 2-6. This is so that I could have more coverage since when I was doing the test I was only able to have about 7 nozzles maximum per bar. It alternates so that the runoff of an initial splash can have a pattern between spaces that weren't originally splashed. The reason why position 1 is known as a 7 special is that there is an electrical box in the top center that I tried to avoid getting wet. What also went into the development of the manifold was considering the total GPM (gallons per minute) of the overall manifold, since I wanted to limit the amount of water need to splash. Because it may be true that will be lots of saturation across the back of the panel there will be more cooling occurring, but there could also be a situation where I put too much water on the panel during a cooling cycle (when water is put on).

Graph 5: Effective Temp Coefficient: This graph demonstrates the effective temperature coefficient that was found for the number of times the water was pulsed during the duration of the 15-minute cooling event. The temperature coefficient was found by developing an equation of the percent change in power output over the change of temperature. The closer the coefficient was to −0.44%, which was the solar panel’s rated temperature coefficient the better the panel was cooled evenly

Graph 6: Collected Power Increase vs Predicted Power Increase: This graph compares the collected power increase from all the days a test was run to what was supposed to be the power increase (predict power increase). The calculated power increase was found by multiplying the temperature drop by the calculated temperature coefficient. The predicted power increase was found by multiplying the temperature drop by the panel’s rated temperature coefficient.

Graph 7: Temperature Drop vs Power Increase in Relation to Water Consumption

This graph compares the temperature drop and the power increase of all the data sets that were collected on days that a test was run while the sun was out, correlating to how much water they used. It can be seen that at certain points some results had the same amount of power increase, yet had different amounts of water splashed on. This demonstrates that large amounts of water aren’t always better to effectively cool the panel. What matters is the distribution of the water.

Conclusion

The hypothesis states that the evaporation of water can be used to effectively cool a solar panel with minimal amounts of water runoff. This hypothesis can be considered to be partially supported. Considering that the minimal amounts of water were able to effectively cool the panel which is demonstrated by the power increase in the data being relatively close to the predicted power increase. But due to the fact that the majority of the effective temperature coefficient was of the panel’s rated temperature coefficient, the panel was not evenly cooled. Also because the element of water evaporation was never measured, a calculation wasn’t able to be made to demonstrate how fast water evaporated from the heat exchange between the back of the panel and the splashed water. During the conduction of the test in the time cycles occurring during the duration of the cooling event, one was able to physically see the evaporation take place, but no way of measuring the evaporation was calculated. The manifold did have the success of being able to cool the panel, letting the temperature drop, and having the power increase, but just not as evenly covered as predicted.

Video 1: This shows how a testing cycle is done with the manifold splashing on the water to the back of the solar panel.

Video 2: This video demonstrates another cooling cycle where the timing has a shorter off time (number of seconds in between each splash). The drip pattern (the runoff from the initial splash from the nozzle) is able to be shown and how it covers some areas of the panel where there was originally no splash occurring.

(Youtube links attached, too)