Yes, you can monitor consumption only. The CTs can be used to monitor whole site consumption or sub-circuits, according to the requirements of the customers. However, such sites do not have a 'Performance' page because there is no solar production being monitored.
Also, if there is no whole site consumption/mains being monitored and only the consumption on the sub-circuits is being monitored, in that case, you would not see the Live Monitor (5 seconds interval data) on the customer dashboard either. Therefore, in order to activate the Live Monitor, there should be at least one channel allocated to whole site consumption (AC Load Net).