Roses can never get too much sun!!!
You may have gotten water on the leaves in the full sun, and the leaves got burnt, or you are lacking in a nutrient, which could very well be if they are in pots. Ongoing watering in pots causes leaching of the nutrients out of the bottom, leaving nothing in the soil.
Browning at the tips of leaves or a scorched looking leaf, usually means a hungry rose and it needs nutrients. You probably have a shortage of potassium or zinc or one of the micronutrients. Give them a good drink of compost tea and fish fertilizer and this should help.
You should also check the acidity of your soil. Roses prefer a PH balance of 6.0 to 6.5. If your soil is too alkaline, your rose will not be able to utilize the nutrients properly.
Roses are extremely heavy feeders, and require ongoing addition of nutrients. When you plant your roses, be sure to add lots of compost, manure, alfalfa meal, some epsom salt, bone meal, etc. to your soil. Also continue to mulch with these nutrients, and water with compost tea and fish fertilizer, and you should have glowing roses!
Hope this helps - let us know how they make out!
If you read a few of the other threads in this forum, and the organic forum, you can find out more about the nutrient needs of roses, and how to get them organically.
VAL (Grandpa's Rose)