Andrew,
The energy market here is deregulated and, as always when that happens, it's fubar.
I just happen to live in a city which has half-way decent prices.
We do have different rate structures for electric heating, etc. I pay a bit more because I support Ökostrominitiativen - environmentally friendly power generation.
No seasonal rates but I pay a fixed sum every month and always get a bit back at the end of the year.
I do know people who are rate-tourists, changing providers regularly to save money. Since the law requires your local provider to deliver power without interruption,it is possible to save money if you have the patience to do it.
Gas is a total disaster, completely incomprehensible.