This post describes a ‘Unicorn’ – something which I would buy if it existed (for a reasonable price).
Z-Wave networks are aimed at Home Automation and build a mesh of a combination of battery powered (mostly sensor) devices which are very sparing on their network use, and mains powered devices, such as switches, which, in addition to their normal function – say turning an appliance on and off, act as repeaters for the radio signals from the battery powered devices.
As Home Automation extends into the garden, it would be useful to be able to extend the network without the need to run mains power to everywhere.
A Solar powered Z-Wave repeater would need to listen all the time for messages to relay onwards – so it’s radio would need to be on permanently, and it would need enough battery capacity to handle the transmission and reception it would, need, and a suitable sized solar panel to keep the battery topped up, even during winter or long periods of low sunlight. A range of models might be needed, depending on latitude and number of devices it is relaying for – or it could be more economic to produce one model which would cover 80 or 90% of the requirements.
This could enable other products such as solar watering systems, open/closed sensors for garden gates, sheds etc, water level sensors for ponds, smart bird feeders which could report when they were empty, detectors for next boxes which show when an occupant enters or leaves (note that nest cameras have a much higher battery and network requirements – so need WiFi and a much larger battery, or Power Over Ethernet), and many other possibilities.