93
Negative electricity prices registered in nearly all European energy markets
(www.pv-magazine.com)
everything about energy production
...heaters are the one thing that's 100% efficient. And if you want to go even further, look up heat pumps.
I mean, kinda? What sort of heater are we talking about and how do we measure its efficiency? But, if the definition is just converting energy to heat, without specifying where the heat needs to be, then sure. Every heater has 100% efficiency. Otherwise, there will always be a loss at transport and others.