Synthetic ice surfaces are no different than any other flooring products with the exception that you can skate on it. With this I mean that in order to install flooring products such as ceramic tiles, hardwood flooring, flooring laminates or linoleum you must have a firm and flat sub-floor. This will help insure that your synthteic ice panels lay flat and the connections are virtually seamless.
Much the same way flooring laminates require a gap around the perimeter synthetic ice also must be treated like a "floating floor" that is allowed to expand and contract with temperature changes. To do this a slight gap must be made around the perimeter and no mechanical fasteners are to be used to secure the surface. This will lessen the "stress" on the surface especially on outdoor rinks in cold climate areas and large temperature "swings".
One of the begest enemies of synthteic ice is REAL ICE. During extreme cold weather freezing of the surface from ice build-up must be prevented. A frozen rink will not be able to expand in direct sunlight which will stress-out the surface and can cause stress cracks if provisions are not made.
If you are considering installing your synthteic ice rink on a grass you will need to install a sub-floor FIRST as grass will not be firm or flat enough to support your rink. A simple way to achieve this is by constructing a "shed deck" by using exterior grade plywood on top of pressure-treated stringers. Using manufactured sheating or materials will provide a good base for your rink to be installed.