Despite claims to royal heritage, Sola now works in the humble environment of a restaurant in the town of La Bisbal near Girona.
According to The Sunday Times, he believed he had powerful links when a private helicopter arrived to pick him up during military service so he could visit his adoptive father.
As a result, he began to send letters to the palace, demanding a meeting with his 'father', but he never received a reply.
He told the paper: "I've no choice now but to put pressure on him.
"Every Spaniard has the right to know where he is from. I don't want to hurt the king or country. I wish Felipe all the best."
He got inspiration from Ingrid Saritau, who also claims the former Spanish king is her father.
Ingrid says her mother Liliane Sartiau first met King Juan Carlos in 1956 in France and again in 1966 in Luxembourg where she was conceived.
In 2012, she said: "My mum told me who my father was while we were watching the TV together."
Her case is partly to blame for Spanish MPs signing legislation that would reinstate his immunity from prosecution, a right he lost when he gave up the throne to his son
Mr Sola believes the Spanish King, said to have bedded more than 1500 women in a 'Don Juan-style' romantic career, met his birth mum during a trip to the Catalan capital in the fifties from a military academy in Zaragoza where he was studying.
Barcelona-based author Pilar Eyre, made the explosive claim King Juan Carlos, 71, had an affair with Princess Diana in a book she published earlier this year.
Another royal biographer, Lady Colin Campbell, has long insisted that the Princess and the King embarked on an affair while on a cruise with their spouses in August 1986.
On July 2 Juan Carlos announced that he would hand over to his 46-year-old heir, Crown Prince Felipe.
- Daily Mail