Most people are probably familiar with photo-voltaic (PV) systems. You see them on plenty of houses and also large arrays on the ground near large campus sites like hospitals and government facilities. If you swing by Denver International Airport you go right past a two megawatt system that will produce over three million kWh annually!
Whether you are building a custom home or an office building it is good to know ahead of time if a PV system is something you want to incorporate. Since the orientation of the system is critical to its effectiveness we’ll want to organize the site and building form accordingly. A ground mount system will require a good amount of area on the site that has to have solar access and won’t be in shade in a couple years should an adjacent building be constructed.
An excellent solution is to put the array on the roof of the commercial project or residence itself. Again, knowing ahead of time allows it to be incorporated successively into the design. I frequently see PV systems that are poorly laid out, primarily on single-family homes, due to site and roof constraints – that is something to avoid.
PV systems work best when they have good southern exposure. That tends to encourage an East/West building axis – the building is longest in that direction. The interesting thing is that this is also a great form for improved thermal performance in our climate. It’s hard to control sunlight on the east and west sides of a structure and easy on the southern side. By better controlling the sunlight we can prevent a building from overheating due to morning and evening solar heat gain.
Of course less heat gain on the building means less air-conditioning and for a home that means lower electricity usage in the summer. In the winter to low sun can be let into the home to supplement the gas-fired heating system.