Are multiple shallow cycles harmful for batteries?

As for all that I've read about any type of dc battery - yes, shallow cycles hurt. That is why such careful planning goes into equipping a home with solar dc. You need to store a bit more than you'll use in a day but not much more. I'm not solar at home but I have a friends who are. Their battery budget came in just enough to cover their normal daily usage in battery bank storage which was perfect, any more battery and it would have gone to waste.