Analysis of Solar Array in a Solar Window Wall
Engineering
EE 195
The emergence of renewable technologies has been increasing dramatically over the past decade. The solar wall concept is an old idea that has been reinvented by Narinder Kapany, to take advantage of the new materials and concepts to integrate heating, cooling and electricity generation. Thus, this new solar wall is to be multifunctional by providing Air Conditioning and solar energy to either residential or industrial buildings. The current embodiment of this solar wall now includes the solar energy function by having a solar array of 60 Parallax solar panels embedded inside the top portion of the window wall and a glycol heat exchanger to be able to transfer the generated heat inside the window wall to an external system. We analyzed the efficiency of the solar array to determine if the array should be static or movable to track the sun, to determine what effects shadowing from the solar panels and structure of the wall have on the array, the efficiency levels of the array based on the direction of installation and to assess the efficiency of the solar wall’s A/C function.
In order to test these factors we created a system to collect, store and sort the voltage levels of each solar panel while simultaneously measuring the temperature for the air and glycol heat transfer solution while collecting data from the solar array. The hardware in the system included eight 8-1 Motorola multiplexers, two Arduino Uno microcontrollers, an Ambient Weather solar meter, two thermocouples and a thermometer rod. The software LabView was used to collect and sort the voltage levels from each of the 60 solar panels, Mathlab was used to analyze the shading effects and Excel was used to graph all other figures. Each measurement for the solar panels and temperature of both the air and glycol inside the wall were taken at 20 minute intervals. Within each interval, the angle of incidence for the solar array was changed between 0˚-20˚ and the direction of the wall with the respect to the sun was changed. It was seen that the efficiency of the solar panels decreased by 50% when the temperature inside the wall reached 40˚C. Most of the shading issues were shown in three downward diagonal patterns across the array and appeared to be independent of the array’s angle of incidence with respect to the sun. The shading is believed to be due to the structure of the wall.
We found that the optimal angle of incidence for the solar array occurred at 10 degrees while the optimal direction of installation was in a south direction (as expected). We also analyzed the data to determine the amount of W/m2h for the optimal direction of installation of the wall and angle of incident of the solar array. We determined that the difference of power collection at the different angle of incidence only varied at most by 1.5%, thus indicating that a fixed solar panel array would be sufficient for near optimal performance without the added complexity of having to move the individual panels. We found that the temperatures of the air and glycol heating/cooling solutions reached 109˚F. Overall the solar array produced energy at an efficiency level of 67%, with the best configuration for the wall to face south at an angle of 0˚. The next step in optimizing the solar window wall is to look at the amount of power versus cost of each of the 60 solar pane and to redesign the structure of the solar wall to optimize efficiency.
