Which systems must comply? As stated in the section title, rapid-shutdown requirements apply to PV systems on buildings. If you are installing a roof-mounted PV system subject to NEC 2014, the rapid-shutdown requirements clearly apply to your project. If you are installing a ground-mounted or similar system where none of the PV system components or circuits contacts a building, the rapid-shutdown requirements do not apply.
This does not mean that all ground-mounted PV systems are exempt from rapid-shutdown requirements. Where PV system circuits from a ground-mounted PV system are physically attached to or penetrate a building, you should apply NEC 690.12. However, in this case, the conductors on or entering the building are subject to rapid shutdown, but the conductors off the building are not. Note that underground conductors that travel under buildings are not considered to be “on or in buildings.” Where buried conductors come up into a building, you are allowed to run them a distance of 5 feet from the point of penetration through the floor before installing a disconnecting means.