To put that power draw into context: A portable solar panel produces 30 kW in full sunlight. Thus you need at least 4 to run BIE at all. But their average power output across a full Nauvis day-cycle is just 21 kW, meaning you'd need 5 of them to power it all the time. More that 6 of a Modular Armour's 25 equipment grid squares just for the BEI and its power! But far worse, covering that 100kW draw through Nauvis's night would demand 226kJ of battery capacity - more than 11 Mk1 personal batteries.
The two solutions I see are:
- Substantially reduce the BEI's power drain. A 10kW drain would mean a single solar cell and two batteries would be enough to run it, and with ~ half the solar cell and 3/4 the battery left over to help with other functionality.
- Make the BEI only cost power when actually standing on a belt.