Solar energy is collected as heat during the day, and circulated into the tank, where enough is stored to continue running the Stirling engines through the lunar night. Most of the plant can be fabricated on the Moon out of plentiful local materials fairly early in the development of a colony. Power through the night from plants produced locally is a key technology for settlement.
NOTE: If you'd like to do something with this model, it's better to get it from our GitHub repo. This one has had its guts removed to reduce the file size. https://github.com/briligg/moonwards Also visit us at www.moonwards.com