Hybrid material mat

A method of manufacturing at least a part of a wind turbine blade, the method comprising the steps of:

• providing a plurality of individual hybrid material mats, wherein each said individual hybrid material mat comprises a plurality of glass fibre rovings provided on a carbon fibre substrate, the carbon fibre substrate consisting essentially of carbon fibres, said plurality of glass fibre rovings arranged in a first layer on a first side of said individual hybrid material mat, and said carbon fibre substrate arranged in a second layer on a second side of said individual hybrid material mat, the first layer of said individual hybrid material mat having at least one carbon fibre tow positioned among said plurality of glass fibre rovings on said carbon fibre substrate within the first layer, wherein said at least one carbon fibre tow provides for a potential equalization between said first side and said second side of said individual hybrid material mat, and wherein said at least one carbon fibre tow extends along a longitudinal direction, and each of the glass fibre rovings extends along the longitudinal direction such that each of the glass fibre rovings extends parallel to the at least one carbon fibre tow;
• arranging the plurality of individual hybrid material mats in a mould, wherein the plurality of individual hybrid material mats at least partially overlap in a stack in the mould such that the stack forms alternating first and second layers of adjacent ones of the individual hybrid material mats, wherein the at least one carbon fibre tow of each said first layer is positioned between the carbon fibre substrates of respective second layers of adjacent ones of the individual hybrid material mats to provide potential equalization across the stack;
• infusing said plurality of individual hybrid material mats with a resin;
• and
• curing said resin to form at least a part of a wind turbine blade.