I can't say I have any experience but I've read a bit. The tip to minimising your maintenance/electricity would be a reasonable water volume, heavily planted with low light plants and under stocking how many fish you have.
I'm not entirely sure what you've got to work woth or what you want, or how much electricity is costing you, but is running say a 5-10g betta tank, or something similar, with a HOB
going to be viable?
Plants you could look at are water wisteria, amazon swords, java moss, java fern, moneywort, duckweed, anacharis, anubias, water lettuce. amongst many. The fast growing stem plants and floating plans will help a lot (wisteria, moneywort, anacharis, and duckweed and water lettuce) in reducing nitrates,somewhat minimising the need for water changes.
A nitrate reactor is also something you could consider to minimise nitrate build up.
Shrimp or snails could possibly be a welcome addition too, helping detritus clean up, the shrimps being a good source from time to time for the fish. Fish can go a week without being fed ok, months perhaps not.
LEDs would be the way to go for minimising electricity. Or you could have it in partial sunlight, but you'd have to be wary of algae.
An alternative to this, but I'm not sure how well ot works for your plans, is a sump with a refugium. It can house fast growing stem plants to reduce nitrates if you don't like them in the tank, add water volume to dilute chemicals in the water (eg nitrates).
All depends on size constraints really, and what you personally want of your tank. Not sure if this has helped or given you any ideas, but I hope it has.
Edit: just found another recent thread you may be interested in: Self-Sustaining Tank???