The give imports and exports, but they don't specify partners.  That would probably be something that you'd have to delve into national databases to get at.

What I've put up here is only the gross generation.  Many states export and import power so basically, generation≠ consumption.  Germany imports power from France, but is a net exporter overall.

As far as those 4 countries (Denmark, Sweden, Norway, and Germany.)

Trade (GWH)
             Denmark  Sweden  Norway Germany
Imports      10427    16052   5285   45953

Exports      11377    14736   15320   62508

So there is a lot of trade, but we don't know with who.  Norway has a huge electricity surplus, and gets nearly 100% of its power from hydro.  Germany produces a lot from coal, and has a more modest surplus, accounting for size differences. Norway has a production surplus of 7.3%, while Germany has an export surplus of only 2.6% of total production.

Trading across an integrated grid could help up the percentage coming from non-hydro renewables, because hydro could be held in reserve to be used when wind or solar wasn't covering demand.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

The Nord Pool market (the Nordic Power Exchange) is the single power market for Norway, Denmark, Estonia^[1], Sweden and Finland. It was the world's first multinational exchange for trading electric power.^[2][3] As of 2008^[update], Nord Pool is the largest power derivatives exchange and the second largest exchange in European Union emission allowances (EUAs) and global certified emission reductions (CERs) trading.^[4] The derivatives and emission allowances and credits market is operated by Nord Pool ASA while the physical electricity market is operated by Nord Pool Spot AS. The international derivative products, the clearing house and the consulting services are provided through the cooperation with NASDAQ OMX Commodities.