Whilst I've managed to create an account with pvoutput.org was simple enough, I found creating one on bdpv.com rather confusing...
Hmmm. I suspect something must be broken on the site - maybe indeed "No space left on device" as in the error message. I've emailed David Trebosc (admin of BDPV, and user 'bdpv' on this forum) to say you seem to be getting an error. I saw "No space left on device" on some pages this morning when adding my December numbers, but it didn't seem to be causing me any problems (of course, I wasn't trying to create an account). Hopefully David will post here (or reply to me).