A friend just sent me a picture of solar panels mounted vertically along a wall at Lincoln Financial Field in Philadelphia. Can solar panels on a wall really work?
Solar panels perform better with direct sunlight. Here in Southwest Florida, the sun reaches a maximum angle above horizontal of 86°on June 21 . On December 21, the shortest day of the year, the sun only reaches an angle of 40° above the horizon. On average, the maximum daily angle, also known as azimuth, is about 63°.
In Philly, the Sun’s average maximum daily angle above the horizon is only 50°.
In both locations, energy production is significantly impacted when solar panels are mounted vertically, but to a greater extent in Florida. Compared to an optimal tilt angle facing south, vertically mounted solar panels facing south would suffer a 42% loss in annual production in Southwest Florida. In Philadelphia, the annual production would be decreased by 33%, still significant, but easier to justify.
Obviously the installation at the Eagle’s home field* is not optimal, but it does produce power and it makes quite a statement, a likely goal of the owner or sponsor.
As the price of solar panels drops, sub-optimal tilt angles become more and more justified. In fact, we already minimize tilt angles on flat roofs in Florida because it costs more to tilt them up and increases the required distance between rows. There’s more value in increasing the number of panels rather than maximizing each panel’s output potential. In fact, mounting panels completely flat (horizontally) only reduces annual output by 8% compared to the optimum tilt angle. (note: a small tilt angle is required to keep panels clean and avoid pooling of water.)
For comparison sake, a solar panel at the equator mounted vertically (north or south facing) would produce about 60-70% less annual energy than a solar panel mounted horizontally.
If you see vertically mounted panels in most any location in the continental United States, the owner is probably just as interested in making a statement as they are in making solar power. However, it becomes more economically reasonable as you move toward northern latitudes.