I have found very few options available for the common man to create a truly off-grid surveillance system. Basically there is the ARLO system that was until recently the king off the field, and the eufyCam 2 Pro system that I recently installed.
ONLINE REVIEW
A great review between the two systems can be found on YouTube at the
Home Tech Decisions channel.
What the eufy offers that most do not, is onsite recording of events triggered by motion and those recordings along with real time feeds are accessible via a phone app off-grid as long as you are connected to the same wireless network.
When the grid is up, you can access the camera's from anywhere in the world, when it is down you must be within 1000ft of the base or wifi router to do so.
STILL NEED 120VAC FOR BASE
You do need to provide power to the base unit (120VAC) and a wireless router, which you likely already have for internet at home.
With a wifi router and the base unit plugged into an inverter on your solar system or a portable "solar battery", you have 24/7 monitoring and video surveillance within 1000ft (wifi protocol limit) of the base unit.
Each camera must also be < 1000ft LOS (Line of Sight) from the base.
You can have up to 16 cameras per base unit (I have had 12 for over a year without issue) and the batteries are charged in place with a Micro USB connection. One charge should last up to a year if there is little motion and you are not live viewing all the time.
Setting mine up for max battery use and in an area that triggers on animals all the time, I have gotten 4 months on one charge. Other camera's I installed at the same time in low activation areas have 80% battery life still.
BOTTOM LINE
The 2K video has excellent resolution, the IR LEDs in the camera's provide great night vision and you can hear and speak through each camera. You can setup sensitivity and masking to suit your motion activation needs.