This one is probably the most developed one.
https://www.raspberrypi.org/blog/nature ... e-cam-kit/
Pi3 are the most power hungry,
Zero or A+ are better for battery operation.
Zero W uses more power for the WiFi/BT.
Longest battery life is if you use the PIR to turn power on to the Pi, it takes video then turns itself off.
Fast booting time helps, I use Ultibo which means about 3 secs boot to snap vid/image time.
You will need a RTC to keep date/time, this could be used to turn power on/off at set times.
Motion based cameras using MotionEye OS or Pikrellcam on Raspbian Lite need the Pi and camera on all the time.
I use both for fixed installs, MotionEye works well with secondhand Sony PS3 Eyecams, $2-6.
A separate Smart Bluetooth module with RTC on board can be used to configure the PI without needing to wake the Pi.
An Adafruit Feather with LoRa could give you long range configuration or checking on vid/image status
This could also be triggered by the PIR sensor.
I have yet to see a very good solution for this using Pi's.
For solar you will need a panel of around 20+Watts on a Zero based system.
I was involved in the first low power cameras for this company http://digilant.com.au/
Even now, nearly 2 decades later, very hard to beat that original low power design but resolution is much better these days
Very few people could do it back then, it was hard to get actual sensors and data sheets, situation still similar today
Now just about anyone can with Pi's and big enough batteries
A simple solution is a Power bank, Zero, Pi Camera and PIR, shoved into a plastic clip-it type kitchen container.
Software wise the PIR can trigger a GPIO wakeup on halt mode, I think that may already be in Raspbian on GPIO4?
Night time with NOIR and you will need IR leds.
Osram have new IR LED with 60 degree angle that nearly matches the standard Pi camera lens.
You can strobe the LEDs to save power, normal Pi cameras don't have the strobe from the sensor coming out but there is a software solution.
Basically you turn the LEDs on for about 2ms at frame rate, getting that synced is the hard bit.
NiMH batteries for solar are easier than special charging circuits for Lithium Ion/polymer.
But I am tending towards LiFePO4 designs until Sodium Ion ones are available.
A good solar design will have a MPPT circuit for optimum solar usage, depends on solar world location.
A Pi solution will not be optimum but it can be quick and mostly off the shelf.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges