I kept my Phals on my South-facing back porch where they received some direct sunlight during the early morning hours. But around 10:30-11:00 they were already partially covered up by the shade of the trees, where they only received dappled sunlight during the hottest part of the day. Then, they would even receive a couple hours of direct evening sunlight before the Sun would set. But as others have pointed out, they were slowly acclimated to this bright light, and were sheltered from the hot midday Sun. The direct light they did receive was only during the early morning and late evening when it was always angled and less intense.
Then, during the hottest part of Summer, when the Sun's the furthest north of the equator that it gets, I had to move my Phals back underneath the shade of my back porch because the shadows of the trees no longer covered them. So they still received morning and evening Sun, but were still shaded during the hottest part of the day. Tho they did receive some very bright indirect light during those hours when the Sun's rays would hit the porch underneath the table that I had them on and radiate back upwards. I do however want to reiterate that this was only indirect light during the middle of the day. The only time they received any direct Sun was during the early morning and late evening hours.
Of course, I had to keep them well watered, which was quite often and even daily during the Summer months. As long as they were kept from drying out too much or for too long, they seemed to stay pretty happy and even stayed in bloom for most of the year. I even noticed one of my Phals that stayed in bloom the longest has even tried sending out yet another bud, but it seems to have stalled for now, now that it's beginning to cool off, and it hasn't gotten any bigger.
I haven't had any cases of sunburn all year and all my 'chids seem to be happy, so hopefully I'm doing something right, lol. Seeing as I gave them as much sunlight as possible, I'm hoping for yet another year full of blooms from them.