FRANKFURT, Jan 15 (Reuters) - Germany's offshore wind capacity more than doubled last year as investors warm up to the technology, helping Europe's largest economy in its ambitious push into renewable power.

At the end of 2014, total installed offshore wind capacity stood at 2.35 gigawatts (GW), compared with 915 megawatts (MW) at the end of 2013, German engineering association VDMA said on Thursday.

Of the 2.35 GW, about 1.05 GW were connected to the power grid, VDMA said, highlighting the need to speed up network connections to reach Germany's goal of having 6.5 GW of capacity installed and connected by 2020.

"At the end of 2015 we will have about 3 GW of capacity connected to the grid, which equals an investment of about 10 billion euros ($11.7 billion) in the German offshore wind industry," Norbert Giese of VDMA said in a statement.

Overall, 543 offshore wind turbines have been installed off Germany's coast so far.

Unlike onshore farms, offshore parks face no limit on turbine size, while steady sea winds allow them to turn about 42 percent of the time, about double the "load factor" onshore.

But accounting for less than 1 percent of Europe's power consumption, it remains a niche technology for now, hampered by high costs and limited evidence on long-term impact from storms.

($1 = 0.8545 euros) (Reporting by Christoph Steitz; Editing by Mark Potter)