Where can I get archived hourly wind speed data for Germany?
The MERRA dataset has data for the world from 1979 to date. It updates frequently.

You can get the data as HDF or NETCDF. If your GIS package doesn't read those, there will be translation packages around the web to convert them into a suitable format.

You'll want the U- and V- wind data. You might want pressure too. And possibly even turbulence data.

If you're interested in using this for simulating wind generation, then I highly recommend the paper by Cannon et al on analysing the MERRA data for wind energy simulation.

You might also be interested in the CFSR data, which runs 1979-2010: in connection with using this paper for wind energy simulation, see this paper by Sharp et al.

(I've previously posted this elsewhere on StackExchange)