recs, page-5

Also the clearing house and $40 price is mentioned here.
https://www.rec-registry.gov.au/faqs.shtml#faq18

STC Clearing House
What is the STC Clearing House?

The STC Clearing House is a new facility under the SRES (Small-scale Renewable Energy Scheme) that facilitates the exchange of STCs between buyers and sellers at a fixed price of $40 (excl. GST). Use of the STC Clearing House for these transactions is optional. If you do not wish to use the STC Clearing House for these transactions, please refer to the REC Registry Online Registration Guide.

For more information regarding the STC Clearing House please contact the Office of the Renewable Energy Regulator on (02) 6159 7700 or [email protected]. The ORER website will also contain comprehensive quick reference user guides from 5 January onwards and is located at www.orer.gov.au.