Also they are very small plants to be producing berries already. It's probably a sign of stress. But full sun is really what you need to produce berries, you will just have to water more if the weather is hot. Feel the temperature of the pvc tube and if it is hot when it's in the sun, maybe try wrapping it with foil, or painting it white to keep it cooler?
I would remove the berries, water more, fertilize and grow a big, bushy plant that will produce normal size berries. The leaves should be twice that size, and darker green than that, and each plant should be 10in. or a foot tall and wide, with many more leaves than that before they are ready to bloom and produce.
Your planter idea is clever, but I'm thinking not really big enough for the plants to develop a healthy root system.