What about a solar powered mesh network build on commonly available LoRa chips and micro controllers ?

Does this exist already? Meshtastic doesn't do IP.

Sure does - MeshCore for example:

Quite active here in Czech Republic for example.

As for the IP protocol - maybe its too much overhead for this use case ?

MeshCore uses PKI and public key prefixes as addresses & for routing/repeating.

	▲	easterncalculus 2 hours ago \| parent \| next [-]
		Did not know this, thanks for sharing.
	▲	radec 3 hours ago \| parent \| prev [-]
		Or Reticulum. Nomadnet over lora works pretty well.

cowlevel 4 hours ago | parent | prev [-]

Who owns the spectrum?

In Europe it is using the 868 MHz ISM band with some duty cycle rules (maximu of 10% of every hour can be used for broadcasting).

In the US apparently 433 MHz is used instead.

	▲	happosai 3 hours ago \| parent [-]
		These bands are trivial to jam should any adversary want.