There are two main disadvantages to HD CCTV.
1080P cameras produce 5 times more data than Standard definition cameras so for a given storage time you will need 5 times the hard drive capacity. A standard definition 4 channel DVR providing 20 days of rolling footage will only give 4 days as a 1080P HD system unless you fit a larger hard drive.
The solution is to increase the size of hard drive in the DVR and / or lower the frame rate (number of images taken per second). Increasing hard drive capacity by 5 times isn't always practical, lowering the frame rate is a no cost solution. In reality it's a combination of the two. We suggest a frame rate of between 3 and 6 frames per second.
Some people promote real time (25 frames per second) HD DVRs. This is the single biggest mistake you could make with an HD CCTV recorder. The amount of data generated is massive for little or no gain. Instead of 22 days rolling footage a 1080P real time DVR would give just a single day of footage. Have a look at our guide to Real time DVR recorders.
You could only record on motion detection but there are some serious drawbacks to this such as proving non delivery of internet ordered products as covered in our recording modes section.
The second thing to consider with HD CCTV is night time performance. Because the individual sensors on the image chip are smaller less light hits them. For this reason it is important to use good electronics. We could halve the purchase cost of cameras whilst still maintaining the same headline figures in their descriptions but they wouldn't work as well in low light conditions because they would have inferior electronics.