This is a great question and one that more people need to ask when considering a solar installation. It is a critical part of your system but since it is out of site under the panels, few people give much thought to it. A full size system can mean up to 90 roof penetrations and it is imperative that every one of them be leak free for the life of your system. An inexpensive system like butyl tape which can be seen in this video does not meet the requirements of the building code, will invalidate your roof warranty and will eventually leak. At the other end of the scale is the PV Quickmount system. It is probably the most expensive mounting system out there but it is also the best. It is all aluminium and stainless steel and even though it costs $1,500 more than the cheaper ones, we feel it is money well spent. We are in business for the long term and we simply cannot afford the risk of a leak in your roof.