When I was looking for a surveillance camera, I came across this LTE camera from K&F Concept.

Two points were decisive for me:
1. The camera should be able to be operated without an external power source.
2. The camera should have online functions.

On point 1:
The K&F Concept 4g camera has a built-in battery. The battery can be charged using the included cable. In addition, a solar panel is included in the scope of delivery, which can be attached directly to the camera or to the wall of the house. In the past few weeks it has been relatively sunny and the battery was always fully charged thanks to the solar panel. I'm curious if that will also be the case in autumn / winter.
To point 2:
The camera has a SIM card slot. A sample SIM card is included in the scope of delivery. K&F Concept offers cloud storage of the video material for a corresponding fee. The camera can also be connected to your cell phone and controlled and configured via the K&F Concept app.

The built-in motion detection activates the camera and sends a push message to the app. The camera can be rotated 355°/ 95° in two directions in the app.
The camera offers a good picture (2K) both during the day and at night.
The two-way sound is acceptable, but depends on where / how high the camera is mounted.

So far I am very satisfied with the product.