Orange juice and orange concentrate are not good ideas. Zest could work out well. But basically most citrus fruits, especially oranges, get a really stale and unpleasant taste when fermented (hence why "orange wine" doesn't exist). Orange zest, on the other hand, can give a very fresh and pleasant orange flavor. I've personally never tried this with cider as I personally don't think apples and oranges mix that well, but if you do try it, I think zest would be the best approach.
Can you get bitter ("Seville") oranges? I've used the zest and juice in ferments with great success, it's like the flavour of orange crossed with the acid of lemon. They're hard to find though, usually only come in season once a year and most get made into marmalade, but they freeze well if you want to stock them.