There are many different types of solar panels. Some are hard panels that are silicone based, while some are flexible thin film. As of this writing the silicone based panels are more efficient but are a little more expensive. The more panels put on the roof the more electricity gets generated, so the incentive is to squeeze as many panels on the roof as possible. Find a reputable solar dealer and they can probably offer you multiple business models to pay for the panels. Options are available from you buying the panels outright and taking the deductions (Federal 30%, possibly state) to the solar provider leasing the roof, selling you the electricity at a set price for a period of years and then taking the deduction. Things to look for from the solar provider are web based software to show the electricity output and some sort of error notification if one of the panels fails (which may knock out a whole string of panels).
If you decide to put the panels on your roof there are some impacts to the roof. The panels are typically warranteed for twenty years. If your roofing system will not last twenty years then it should be replaced before the panels are installed. Installing a new roofing system after the panels are installed is much more expensive. Can the cost of a new roofing system required for the installation of the solar panels be included in the Federal or State deduction? We have heard it may be – consult your tax adviser as it could be a substantial amount of money.
The waterproofing layer should be relatively tough. If a single-ply membrane is used it should have a reinforced scrim in it (all PVC and TPO membranes have to be reinforced, while EPDM comes in reinforced and non-reinforced). Aisles should be left between the panels to allow HVAC technicians to service machinery. Depending on the traffic in these aisles walk pads or walkways should be installed. The fewer penetrations the panels make the less likely the roof is to leak. If the panels rest on the roof there should be a buffer or slip sheet between the panels and the waterproofing layer. It makes sense to allow for a few weeks to elapse between the installation of the new roof/waterproof layer and the installation of the solar panels. This time allows for some rain to make sure the roofing is leak free before being covered by the panels.
If you have a manufacturer’s warranty on a roofing system (and we highly recommend this) the roofing system should have been inspected upon completion. Many manufacturers require a re-inspection upon completion of the solar installation (for a small fee). One issue in installing the panels is how does a roofer repair a leak. If the roofer can’t get to or find the leak some of the solar panel(s) may have to be removed and later re-installed. Manufacturer’s warranties do not cover this expense (termed overburden).