Global installed wind power capacity is expected to rise to 650.8GW by 2020 from about 364.9GW in 2014, according to a new report from research and consulting firm GlobalData.

According to the report, the future demand growth is expected to increase worldwide investment in wind energy projects to $101bn by 2020 from $70bn in 2013.

Wind turbine manufacturers developed about 11% of gearboxes, 48% of rotor blades and 43% of generators in-house in 2013.

In 2006, about 10% of gearboxes, 62% of rotor blades and 37% of generators were manufactured in-house, the report reveals.

GlobalData senior analyst covering power Prasad Tanikella said: "Depending on wind power component supplies, turbine manufacturers make strategic decisions over whether or not to produce the equipment in-house.

"Some of the major manufacturers, such as Enercon and Vestas, prefer to develop components within their business structure, to avoid issues with quality control and design confidentiality."

Tanikella noted that that the turbine manufacturers are seeking several component suppliers for smooth production due to steady growth in the global wind power market.

Various long-term agreements are being signed between turbine manufacturers and their suppliers.

Tanikella said: "Overall, component costs are decreasing as a result of reduced raw material prices. We therefore predict a low growth rate for the wind turbine components market over the forecast period, despite wind power investment seeing a significant increase by the end of 2020."