Art. 17 III Directive 2019/944 for the internal market for electricity:

"Member States shall ensure that their relevant regulatory framework contains at least the following elements:

[...]

(c) non-discriminatory and transparent rules and procedures for the exchange of data between market participants engaged in aggregation and other electricity undertakings that ensure easy access to data on equal and non-discriminatory terms while fully protecting commercially sensitive information and customers' personal data;

[...]"