“Spanish consultancy AleaSoft Energy Forecasting recorded negative hourly electricity prices for all but one European energy market it analyzed during the first week of April, including in the Spanish and Portuguese markets for the first time. It also registered an all-time production record for photovoltaic energy in Portugal and the second highest value ever recorded in Italy”
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.