That might be their real problem. I mean, everywhere else on the planet, the value of menial labor greatly exceeds the cost of the lighting a human needs to be able to work. If they are, indeed, only providing lighting during daylight hours, they are only utilizing 1/3 to 1/2 of the industrial capacity they have invested in. They bought a tractor plant, but because they won't turn on the lights, it's production is far short of its capacity.
For want of a lightbulb, the production was lost. For want of production, farming equipment was lost. For want of farming equipment, the harvest was lost. For want of a harvest, the people were lost.
If the value of electricity to run a lightbulb so greatly exceeds the value of human labor, I would expect that they would have human powered generators to convert low-value human labor into high-value lighting, so that other laborers would have the light they need to produce.