According to the journal's instructions for authors, it is recommended to use the MDPI style, which is up-to-date. (And the "Energies" style is a dependent of the MDPI style). Could you provide more details on where the DOI is missing?
MDPI journals don’t include DOI in references (they used to, but stopped several years ago and removed the DOI from the MDPI Zotero/CSL styles themselves)
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Could you provide more details on where the DOI is missing?