Hello, thanks for your comment!
Power is a surname strongly associated with County Waterford, because it is one of the most popular surnames in the area. You're certainly right about the name's French origin, the name Power is derived from De La Poer, as you rightly suggest. The De La Poer family were Normans who left France and came to England with William the Conqueror in 1066. They then came over to Ireland with Strongbow in 1171, when Ireland was invaded by the Normans. To reward the service of Robert De La Poer, King Henry II of England gave him lots of land in County Waterford.
The De La Poer family continued to be rich and powerful throughout history. In 1704 the male line ran out and the only De La Poer left to inherit the family name was Catherine, who married another aristocrat, Sir Marcus Beresford. Their descendants were known as the De La Poer Beresfords, to honour both sides of their powerful family tree. Catherine and Marcus's son became the first Marquess of Waterford, and their descendants still hold that title and live in their ancestral home, Curraghmore House.
Although many people in Waterford are called Power, they are not necessarily related to the De La Poer Beresford family. De La Poer is believed to be derived from the French word 'poor', so many of the Norman invaders who arrived in Waterford probably had that name because they would have been descended from French peasants. I haven't come across any story about a shipwreck, but it could well be possible!
I'm afraid that there isn't yet an Ireland XO page for the parish of Portlaw, but my recommendation would be to look at the 1901 and 1911 census if you haven't already, which might give you a few more details. You can also check out our local guide for Stradbally parish, in case any of the historical sources listed there are of use!
Best of luck with your search!