Intermediate demand, also called intermediate load, refers to the amount of electric demand created by a customer or a group of customers during the hours between minimum load hours and peak load hours. For many utilities, intermediate loads occur between the mid-morning and late afternoon. However, this varies by location and is often different during colder winter months. In regions with significant amounts of rooftop solar production, intermediate demand may occur earlier in the day or may not be applicable. System operators must ramp supply sources as loads grow. The sources of supply turned on or ramped up to meet demand in the intermediate period are often called intermediate generation.