UK Emissions Trading Register and/or the Ozev Scheme for EV Charger installers?

[Sparky's Auntie]

Hi there, please be patient with me because I'm old and still learning. My electrician nephew is being inundated with EV Charger requests. He's fully qualified and has NICEIC accreditation too. I registered him for Ozev, but if I'm honest I don't understand it. Should he also be on the UK Emissions Trading Register too, and what are the benefits?

I've googled and trawled through the forum but you lot all seem to know what you're talking about, and I wondered if you could explain it to me in lay mans terms