Yes - the libbi battery and inverter can be installed outside.
The libbi controller must be installed inside.
See full product details in the libbi Datasheet
What about Relative Humidity?
Relative Humidity (RH) is defined as the amount of moisture the air can contain as a percentage of the maximum moisture it can hold, at a given temperature; where the dewpoint temperature and actual air temperature are the same. It doesn't mean that the relative humidity must be 100% percent in order for it to rain — it must be 100% where the clouds are forming, but the relative humidity near the ground could be much less.
The Libbi Inverter has been tested to IEC60068-2-30, which specifies a minimum of 95% RH. In terms of relative humidity testing, it is difficult to maintain >95% RH in a test chamber, hence why this figure is quoted on our datasheet. Note, the Libbi battery has a maximum RH of 90%. The product is rated at IP65, protected against dust ingress and jets of water from any direction. Therefore, installing both the inverter and battery in a suitable location outside is acceptable.
Will libbi work when it's freezing outside?
While the lowest recorded temperature is -26.1°C, in Newport in 1982, the product may be installed outside of the home, where temperatures would typically be greater than -10°C.
However, if the ambient temperature drops below -10°C, the firmware monitors the internal temperature and may inhibit functionality. Through charging/discharging the equipment will self-heat, therefore the relative temperature between ambient and the equipment, should not affect the normal operation.