A bin level monitoring system utilizes an optical sensor housed in a housing. The housing is attached at or near the opening of a bin or other storage structure without the need for a hanging bracket. The sensor housing can be clipped or directedly attached to the bin opening or lid of the bin, such as at the lip of the opening. The shape of the housing aids in directing the particulate material into the bin housing, while protecting the sensor. The location of the sensor and housing provides ideal location to best monitor and evaluate the amount or volume of material product in the bin at a given time.