I’m looking to use a pi 5 8gb board to build a security ip camera system.  It would manage and run up to 8 cameras and I would like to have a solar powered backup battery so if the power goes off it will still record and have web browser access to the recordings.  So could  pi 5 with 8gb have enough power to do this? The pi would be basically a nas that would have the ability to access each camera as well remotely control them like adjust panning focus and resolution.  The pi would have a onboard ssd drive to store the video/sound recordings and then after a period of time rsync (or what ever copying app) those files to either a cloud storage or offsite storage solution.  Has anyone done this before if so what were your results.

You are doing this all backwards. Determine your security needs and then build a system around your security requirements. A Pi is not a security requirement, it's a very low powered computing device that may or may not work (probably won't be powerful enough) to run your security system built around your security requirements.

The only things I see about PI security systems is integrating one camera with the Pi. Thats not a very good security system.

Look at Blue Iris which is the king of DIY home IP camera systems. It only runs on Windows, but you can use a intel box that supports quicksync for accelerated video transcoding.

ok thanks

Not powerful enough.  Recording video, especially at 4K with motion detection, takes a fair amount of processing power and memory.   My Blue Iris system that is running 6 1080p @ 15fps cameras is an AMD 5900x with 32GB RAM.   Runs about 50% CPU and 50% RAM, depending on how many remote devices I am watching it on.  16TB hard drive keeps about a week's worth of footage.

Also recording multiple video streams to a SSD will wear it out pretty fast.  I've tried.