Tank will have a 3D background, so not much if any sun light will pass through the back - only the sides of the tank. No one's home during the day, so the lights will only be on from 6 - 9 pm. Thoughts and experiences?
If your tank is being hammered with direct sunlight for most of the day, IME, you will suffer huge algae issues. I would avoid the DSL at all costs.
Seems to me that the sun heating up the water would be an issue. Even though the back would be blocked from the light, the heat will still warm up the tank.
I have had problems with spot algae when direct sunlight hits it. On an unrelated issue please be aware that sunset hygro, hygrophila polypserms rosanervig, is highly invasive and is on the federally banned list.
http://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/weedlist.pdf