leaving it as just "test G59" would probably be meaningless for all, except a tiny minority specialised in that field, and even then it would mean anything ONLY to those who know UK regulations inside out.

You need to add some minimum explanation, and possibly a reference to the actual standards.


What is G59 generation?
 G59 is an industry standard for generators greater than 16A per phase
◦ Energy Networks Association Engineering Recommendation G59/2-1
“Recommendations for the connection of generating plant to the
Distribution System of Licensed Distribution Network Operators -
Amendment 1”
 Up to 50kW there is a provision for type tested equipment similar to G83;
however
 Applications greater than 17kW per phase must use G59 approved relays
unless G59 type tested inverters are available
 G59 applications must be submitted for system studies and associated
network reinforcement where necessary prior to connection.

https://www.ofgem.gov.uk/ofgem-publications/43620/dnos.pdf