Installing Rooftop PV
How homes are evaluated for solar, how a system works, and how it’s installed.
Lauren Coyne is the director of member collaboration at Amicus Solar. Before taking her current position, she worked with us at Namasté Solar, an employee-owned cooperative based in Denver, Colorado. Despite the fact that she’s spent the last decade working in the solar industry, Lauren has never lived in a home with a photovoltaic (PV) system—until now. We recently installed a 7.93kw system on Lauren’s house.
Though each job we do is a little different depending on how the home was designed and built, the type of roofing, and even the city we are working in, Lauren’s project is a good example of how we evaluate and install new systems on most existing homes. At Lauren’s house, the four-man crew simultaneously installed electrical equipment at the meter, ran conduit and pulled wires, and laid out and installed the feet and rails—known as “racking”—that holds the modules on the roof. All told, the system took two days to install.
Evaluating a house for PV
Most homes are great candidates for a PV installation; the exception is if they are significantly shaded. The systems are most effective when they are installed facing south. East-facing arrays are our second choice due to the development of afternoon clouds in our area, but west-facing roofs are still viable, just slightly less productive. North-facing roofs are typically not used for PV installations.
For optimal efficiency, modules would ideally be tilted to an angle that matches the location’s latitude. Unfortunately, this is rarely possible. For our location, the ideal pitch is approximately 39°, since Denver is at 39° latitude. In actuality, this roof had two pitches: The south-facing roof is tilted at 45°, and the east-facing roof is tilted at 30°. With these conditions, there is only a minor reduction…