A mounting pad system for securing equipment, such as an HVAC outdoor unit or a standby generator, is provided in the form of a lightweight fillable pad member having a plurality of receivers located on a top surface of the pad member. The receivers are associated with attachment points located on the equipment and are used to secure the equipment to the pad. The pad member contains a filling port on its top surface and is configured as a molded hollow shell containing a gelling material which, when mixed with water, provides support to reduce deflection of the pad member caused by the equipment secured to the pad, prevents damage to the pad that would otherwise be caused by the expansion of internal contents upon freezing and prevents leakage of internal contents of the fillable pad in the event of an unintended breach in the hollow shell. The pad member is provided with at least one through-hole that acts as a supporting structure.