There are three technologies in the PoE domain-end-span devices (also called in-line powered switch), mid-span devices, and powered patch panels. All these have pros and cons:

• A typical end-span device comes with a lower wattage than required by the device. So an additional power supply unit is required to supply the required power. Also the mean time between failure (MTBF) of a powered switch is 20 percent more than that of a normal non-powered switch, because of all the additional power equipments going in. However, the biggest drawback is that the powered switch transmits data and power over the same pairs inside the cable, thereby increasing the chances of data loss.
• A mid-span device on the contrary resides between the switch and the patch panel. The biggest differentiator of mid-span over end-span is that the data pairs and power pairs are separate. This helps maintain the data integrity.
• The powered patch panel is an attempt in saving the rack space. The biggest problem with the powered panel is that it restricts the moves, adds and changes (MACs). Also, in an existing setup if you want to make it PoE-ready, the only option will be to go for a mid-span. Like an end-span device, the panel also transmits data and power over the same pairs inside the cable, there by increasing the chances of data loss.