Webcam for remote location

Hi,
I’d like to build a webcam system that runs from the battery and solar energy. My target hardware is:

  • Raspberry Pi zero W
  • Raspberry camera module v3 wide
  • external wifi antenna or
  • 4g USB stick

I understand the power consumption of a RPi zero w is about 120-150 mA at 5 V. When it takes pictures, it is higher. I might be ok with the external wifi antenna (no additional power consumption) but might need a 4G USB stick with a SIM card. That consumes additional mAs for sure.

I’m not really good at these calculations, but I guess the total consumption per day would be:
200 mA x 5 V x 24 h = 24 Wh.
If my battery is a 100 VA battery, does it mean the camera could run 4 days without a solar charge?

In principle I could take 1 photograph every 5 or 10 minutes and put the RPi into some kind of “sleep” mode. But I would be interested to make long exposures during night time.

Has anyone built a similar system before? Or, is there something on the market like this?