This slide shows that in a photovoltaic unit, the management of heat is important.  Furthermore, any material which could potentially produce oil or residue that could collect on the cell would not be suitable. On a typical unit there might be several different thicknesses of materials being used.  This can be determined by the design of the housing, the type of component being used, and the power that needs to be dissipated.  Traditional silicone based materials would struggle to fulfil the design criteria here as over-compression could lead to oil bleed whereas traditional non-silicone products could be too hard to remove significant tolerance stack-up. T-Global can manufacture custom moulded shapes if there is a specific need.  This can be a nice solution as it eliminates extra labor to place additional pads and the logistics and packaging can be unique to how the customer wants it.