I have learned however that power should be turned on every few months or so otherwise a SSD can lose data. I've had my desktop off for about 2 months and was still good.
Laptops are being shipped with the OS installed on SSDs, some of which wait even one year before their first owner turns them on. With only months of data retention available, those systems would be DOA for many customers.
Even at the end of their service life, when the unit has reached it's manufacturer TBW rating, a SSD must still be able to ensure data retention for
at least 1 year at 30C. For a drive that is well under it's max TBW rating, data retention is significantly longer. (many years)
It's true though that keeping a SSD turned off in a hot environment (over 30C) can result in drastically reduced data retention, and can lead to data loss. Moral of the story: if kept off for long periods of time, store your SSD in a cold environment (bellow 30C).