are you hoping to just use a solar panel, or a solar system with charge controller and a decent battery setup to provide the power feed to the camera?
The panel only will struggle to provide a stable 1 or 2A feed I would think, especially if there is any cloud cover and as the sun progresses through its arc as the day ticks by, giving more/less output from the panel so the camera operability may well be intermittent. Then of course at night there'd be no power.
For the battery bank approach you'd need to size up the batteries according to the max drain rate you anticipate for the camera which will vary when using the PTZ functions and also any IR. The batteries are likely to be either SLA (bulky, heavy) or Lithium (smaller, lighter and expensive) and the panels would need to be sized to deliver a lot more current than the camera drain if you hope to recover charge during sunlight hours.
All in a pretty expensive way to go compared to powering it from the normal main electrical feed, any particular reason for wanting to do it this way?