Low-cost wind, solar, nuclear, and hydro can lower wholesale prices.
Grid operators generally use the lowest-cost available power first while keeping the system reliable. Wind and solar have no fuel cost; nuclear and much hydropower also cost little to keep running. When these sources are plentiful, higher-cost plants run less often and wholesale prices fall.
When clean power is abundant, prices can fall to zero or below. Local grid data shows which data centers can reach that power.