I have heard that there are some Solar Charged Motion sensor Monitored systems available that might be what You need! They untilize a cellular signal as an alternative to WIFI and Your regular ISP!
I think that one Company calls there's a Yard Cam or site Cam ???
We are in Canada ,but these are American Companies, so No I'm not advertising any particular product. We need something similar here in BC ,but since We travel to the US and Mexico ,haven't found a solution.
Thinking about asking the neighbours to keep their eyes on Our place while We are away!