We've put a few applications into NEDL on behalf of our clients. In general they are cautious about 10kw machines: mainly due to overvoltage and loss of mains - the loss of mains issue can be sorted with a second relay but the overvoltage issue is harder to deal with.
However in all occcasions where there have been difficulties with a 10kw, they have been ok with a 6kw machine - under G83 so it practically plug and play.
So with a 6kw machine the only major hurdle is planning, and if you habe permission from the national park, then that's already sorted.
As Bryan says a 6KW Eoltec produces almost as mush as a 10KW machine, so it might be worth exploring. Pls let me know if we can help
Ben Cosh (an impartial installer)