Their system is designed to easily start and stop to take advantage of wholesale wind and solar electricity rates, which are more like $0.02/kWh during certain parts of the day and times of the year. They sacrifice uptime for even cheaper electricity. If their capital costs and fixed opex are low enough this is a good strategy.

Here's an article about this strategy form the CEO: https://www.cell.com/joule/pdf/S2542-4351(20)30002-7.pdf