First you need to know how good is your wifi coverage where you will installed this camera, as a rule of thumb if your phone 2.4Ghz can get decent speed, then should be no issue. You can get those battery ip camera with optional solar panels. Not that I recommend this model but here is the link as an example! Solar Ezviz

And for those of you still using default/simple password for your HIK/Dahua quickly go update to latest firmware & changed to a more secured password.
IPVM