Most Power over Ethernet (PoE) devices can easily be powered by an off-grid solar power system. Whether it's a camera, radio, audible alarm, or some other device; a properly designed solar system can support the load for many years with minimal intervention.
Most important is understanding the load. While many specification sheets give the maximum power consumption, most devices do not consistently operate at their maximum value, frequently you can also find a "typical" or "average" power consumption. Using the typical values can make your system cost effective and reliable. Also the operating voltage of the PoE device should not be a concern as a PoE router can be used to power the PoE devices. Many PoE routers can accept a nominal 12VDC or 24VDC input and produce an IEEE 802.3 output required for the load. It is important to add a conversion loss to the calculations to account for this, typical self consumption by PoE routers are less than 3W.
And one other consideration, since you already have communication to your PoE device, why not use a solar charger controller that has Ethernet capabilities. This will allow you to remotely monitor your system and make adjustments to increase the reliability and life of the components.
Let us design you a system and specify the components to support your PoE device.