In this example, you could probably have your cake and eat it too.

If your energy bill was going to be $200 on the credit price, but since you stream your sats, it costs you the equivalent of $160 in btc terms... even if you're irresponsible with your energy use it might cost ~$180, you'll still end up saving more sats than if you were consuming normally at the credit price.

I'd assume once your wallet runs out then they'd just start charging the credit price and bill you if you don't top up within a certain period of time.