“ag su solais na greine”
or
“ag su solas na greine” ?
I would assume the first, but I know the rules on genitives following verbal nouns are weird if there are other qualifiers (at least this is the case according to Nualeargas).
ionsú sholas na gréine (the absorption of the sunlight, ionsú mar ainmfhocal gnách) a déarfainnse.
Ach:
Tá X ag ionsú solas na gréine. (X is absorbing the sunlight, ionsú mar ainm briathartha)
Ní cheart “solais na gréine” a úsáid, ceapaim.