Most PV systems are installed within a few days of installers starting work. It’s likely to take longer to get the installers there in the first place and to qualify for any solar rebates, credits, or incentives prior to installation of the system. If you’re planning on setting up a net metering system, it may also take the utility company a bit longer to set up a bidirectional electric meter.
It’s possible to install solar on a home so quickly because modern PV systems are developed for easy interconnection. Many modern PV systems are almost like plug-and--play electronics these days, with wiring integrated into the panel, ready for hook up to an inverter, which converts the direct current power produced by the panels into alternating current used by most appliances in your home.
With a flush-mount rooftop PV array, the solar equipment installers simply need to install the panels directly on your roof, wire them to the inverter, shut the power off to your home (should only take a few minutes) and hook the inverter to your home and the grid (when installing a grid-tied system). Installing a battery back-up for non grid-tied homes takes a little longer as well.
Depending on where you live, some roof-top mounted systems need a greater tilt or their orientation must be slightly out-of line with the roof. For such systems, a mounting rack is needed for the panels. It takes a little longer, likely a few hours to a day or two.
If you’re installing a heliostat (sun-tracking) or PV system in a field, it also won’t take much time to install, just enough for the cement foundation to cure, the mounting system to be set up, the panels wired to the inverter, and the wiring to be tied to the home or building where you use the power.
Talking with an installer or a friend that’s already installed solar can be a huge help in learning what to expect when installing a PV system on your building. They can tell you how long it will take, but more importantly (if you want to save money on the system), they can tell you how much time you need to apply for all the incentives that will make your system’s payoff much shorter.