Some of these NUCs support a wide range of DC support voltages from 12-19V DC, probably making them ideal for custom made DC-DC converters or converters with not so good voltage regulation.
This one has 12-19 V DC support https://www.intel.com/content/www/us/en/products/boards-kits/nuc/kits/nuc7pjyh.html Probably we can integrate with a 12V solar PV system having a lead acid battery whose voltage varies anywhere from 14.4V when the solar power is available to 12.56V at full charge to 12V having at 20-40% remaining charge. Adding a DC-DC converter can boost the voltage to desirable ranges.