How much sun do peaches need to fruit?

Question

How much sun do standard peach trees (pruned short) need in order to set fruit, if they have plenty of heat?

These particular peaches are seed-grown (so probably not exactly like the parent, which I think was an Elberta peach), and they may have crossed with our old nectarine tree.

Anyway, a relative of mine wants to plant them somewhere where other trees will be blocking most of the morning and early afternoon sun. I'm not certain they'll have enough sun to set any fruit (when they're mature; they're currently only about three years old, growing in a raised bed, in need of transplanting out). The rest of the afternoon sun will likely be partially filtered, too, but much lighter.

Answer 1

From experience, in the hot summers of northern Portugal, peaches fruit even under partial shade but the fruit is not very sweet. The more direct sunlight the sweeter the fruit seems to be.

Answer 2

Agree with Organic's answer - you may get fruit setting, but without sufficient UV rays on the foliage, less starch will convert to sugars within the fruits. They may ripen quite well, but will be less sweet.