"a great solace" is correct and can be used in written English.
It is typically used to refer to something that brings comfort or relief in difficult times. Example sentence: "The support of her family was a great solace during her difficult time."
Friendship has been a great solace.
And this is a great solace to many — for instance, Christian ideas of redemption and reconciliation.
During her recent separation, she found practising Beethoven's concerto a great solace.
In both cases the lure of the old-time religion is a great solace to the defeated.
I remember on Twelfth Night – a worrying time, during which he was a great solace to me – I was trying to run through something with the cast and I had a large stick of some sort in my hand.
It won't happen, I'm really underneath utterly in love and sold on my Elizabeth and it's a great solace to me that you are with Lota, and I am sure it is the will of the heavens that all is as it is.
This became a source of great solace to her, in her paralysis; she had no idea, she later told me, that such powers of memory and imagery were available to her. (I now suspect that such powers are not too uncommon in visual thinkers; I know one artist, a highly geometric thinker, who does diagramless crosswords mentally, manipulating the letters and their squares in his head while he is painting).
A great source of solace has been her friendship with Rosie O'Donnell, whom she met at a screening seven years ago.
When you spend all day alone with patients — which is to say alone — the company of colleagues becomes a great source of solace and reassurance and of stimulation.
As a parent, I have taken great solace in Winnicott's maxim of being not a perfect but a "good-enough mother".
