Can it be implemented with reasonable means? – Many ideas never make it because they make a product too expensive compared to the value they offer, or because you would need 20 years of research to find a solution.
What big an impact could your idea have? How is your idea answering any of the UN sustainable development goals (SDG’s)? What national challenges is your solution addressing?
Would your customers buy only once or would they come back regularly? – E.g. an indestructible fridge would be a great idea – but each customer would buy only one in her/his lifetime and you probably could not build a sustainable business.