The Description of the SAC Canopy AC Array
Not many people know that we actually have two PV arrays here on campus. The second one, called an AC array, is rated at 4.3 kW (much smaller than the Aquatic Center rooftop array [342 kW]) and is installed top of a canopy covering the sidewalk leading up to the Calloway Student Athletic Complex (SAC). You can see the AC array in the photo below, which was actually taken from the roof of the Aquatic Center. The square roof at bottom center is on top of the entryway to SAC; just above it, you can see the curved canopy covered by blue-colored solar modules. The photo here was taken just before the 1996 Olympics. The fences in front of SAC were part of Olympic security.
This next photo shows the canopy from ground level. This system was designed by Solar Design Associates of Harvard, MA. It consists of 18 240W Solarex multicrystalline Si modules.
On the back of each module is a power conditioning system (PCS) made by Advanced Energy Systems Inc. in Wilton, NH. These module-integrated PCS (MIPs) can be seen in the photo below. The smaller boxes with the rounded corners and the two conduits coming out of it are the junction boxes in which electrical connection to the PV modules are made. The junction boxes also house the bypass diodes (8 diodes, one for every 18 solar cells). Next to each junction box is a MIP. There are two MIPs visible in this picture. The one on the right, the slightly larger and squarer (and darker) one, is an older version. A newer version is seen on the left. This newer version incorporated some improvements which were field-tested in this array. We have recently installed the latest version of the AES MIPs (the "MicroInverters").
The above photo also shows that the modules in our AC array have a clear backskin; the moisture-proof sheet that covers the back sides of the solar cells in the module is transparent. In this way, light can get through between the solar cells, and the interconnections between the solar cells can be seen. Also the PV modules themselves are the "roof" of this canopy. Not only do they provide electricity, but they also provide shade and shelter. In this way, this system is also an example of how integrating PV into building structures increases its value and makes PV more economically attractive.
The electricity from our AC array currently is being fed directly into the main service entrance of the Calloway Student Athletic Complex (SAC), but it might later be used for something specific, such as charging an electric vehicle, batteries for lighting, or some other application. Our modeling predicts that we can expect just over 5 MWh of energy production from this array each year.