Solar powered LTO battery for 5v use below freezing.
That is one of the enclosures using the 18650, but I don''t know the specifications of that solar panel. This "Unify" enclosure is similar, but designed for a slim battery, and with this solar panel; Solar Panel Specifications: Open circuit voltage: 6.1V (±10%) Short circuit current: 95mA (±5%) Voltage at nominal power: 5V (±10%)