I've wondered how the British hobby has handled their energy costs. It seemed like a lot of people were leaving the hobby when the energy crunch hit there.
Tanks aren't efficient heating sources, though I think we should all say they are to grow the hobby. I mean, telling the truth is so 20th century. If you build an insulation wall around a tank, it looks awful, but you can do things. Some insulation is good. A tight cover is good. Several tanks bunched in a room together is better than one. You can then heat the individual room.
And as I always repeat, research saves money. Look at the temps your fish really need, not the ones the pet store says. This hobby was popular before 99% of us were born, and in my Canadian environment, houses were poorly heated back then. Tropical fish will die if cold, but if you can maintain their lower range natural temps, they thrive. I know local aquarists who insist on having tanks in the 30s/80s, and who are harming their fish and their budgets with that level of heat. Look into it, and a lot of fish are fine at 22-24 decrees, but are kept at 26 to 30. It's expensive and wasteful.
I bought some preset heaters cheap at one point, and they kept their tanks at 26c. Why? The fish liked 24c.
Follow this and there will be some unemployed Discus and other really warm water species - but we don't keep many of those.
My neighbour up the road put in solar panels, and I hope to talk with her in the Spring. It's a big cash outlay here, and in comparison to
@fishorama 's California habitat, our energy demands for heat are way higher. Plus California is rumoured to have this mythical thing called sunshine. That thing that vaguely glows greyly through the clouds is apparently free range down there. People who attempt to sun worship here rapidly become atheists.