STCs – Everything That You Need To Know

As of 20th July 2017, the prices of STC have dramatically fallen. Unfortunately, that affected every single solar industry company in Australia. The STC dip price has caused an enormous problem within the industry, and in turn, increased 5kW solar power systems costs by at least $1000. However, do you know how STCs work, and when the prices expected to drop again?

The first question that you need to know is what STCs are? Small-Scale Technology Certificates are part of a government incentive scheme for householders and businesses that have solar power systems up to 100kW. That scheme is called the Renewable Energy Target, or RET. For every megawatt-hour of renewable energy that is generated by an accredited solar panel, they will receive an STC.

STCs – How Are They Calculated?

The number of STCs that you are entitled to have some particular prerequisites for the calculations. In this section, we will take a quick look over what those are, and how you can calculate the number of STCs that you are entitled to.

Stcs Calculator
Stcs Calculator / Photo by Ashraf Ali
  1. Complete solar energy system size. – This part is pretty easy to calculate. It is the number of panels multiplied by the wattage produced by each panel.
  2. Solar zone rating. – For Australia, the country has four zones. Each of those zones has different classifications that you add to the multiplication. If you do not know which zone you live in, then you can download a list of zones by postcodes.
  3. Years remaining. – The final piece of the puzzle is how many years remain until the scheme phases out. From 2017 till 2030, there are different numbers that you multiply. Therefore, they went from 14 in 2017, down to 1 in 2030.

Therefore, for example, if you have a system capable of 6.48kW, with a 5kW inverter and 24 x 270W solar panels in Perth, you use this as your calculation:

6.48kW x 1.382 (zone 3) x 11 (2020) = 98.50896 STCs.

If you wish to make a calculation based on your own circumstances, please check this online calculator.

Value Of STCs

STCs are not a fixed price value. They are very much like shares in this respect, as they fluctuate following supply and demand.

Value Of Stcs
Value Of Stcs / Photo by Adam Nowakowski

However, as with stocks, owners, and registered agents of these small-scale renewable energy systems can sell through two options:

  • Open market. – Here you can sell your STCs for an uncapped amount.
  • STC Clearing House. – These clearinghouses have a fixed price to sell your STCs. At this point in time, those prices are $40 (ex GST) each.

However, there is a process that you must follow to trade those STCs. In the next section, we will look at the process.

Trading STCs

The process is this:

  • Certificates need to be created and registered with the REC Registry.
  • However, the price will depend on where you are selling, as described above.
  • Negotiation can then take place via the seller and buyer. However, that negotiation is only for open market sales.
  • Payment made directly into the nominated bank account of the seller.
Trading Stcs
Trading Stcs / Photo by Austin Distel

The clearinghouse can have some significant price differences. Furthermore, they can also go into a surplus. It is when there is a surplus that those prices are immensely lower than that of when there is an undersupply. Knowing what the renewable energy target is of the year that you are in is how you calculate if there is a surplus or not. Therefore, the longer you wait, the lower the price will be, hence the problem that we now face.

At the time of writing this, the STC price at the open market is $38. Therefore, there is no reason why anyone would purchase through the clearinghouse, even if there is a surplus. Furthermore, you need to know that STC sales will have a different turn around times, based on the number of sellers and buyers. If there are more buyers than sellers, your STC will sell instantly. However, if there are more sellers than buyers, you could sit on yourSTCs for an infinite amount of time.

Solar Rebate

As you have seen, the speed at which you require a sale can have a dramatic impact on their cost. However, if you wish to sell them quickly, some retailers offer you a POS (Point Of Sale) cost to sell them on your behalf. Many of the solar customers will decide to exchange their STCs for a discount on their PV system. However, one thing you have to note is that the lowest price an STC has held is $16, while the cap remains at $40.

If you use that calculation above, at a median of $28 per STC, you will see that you can gain a $2,758 discount on a high-quality system, which equates to around 20%.


It is unlikely that the price of STCs will rise again because of the changing and decreasing the third point of calculation. Therefore, you will probably never get a chance as good as today to sell and upgrade your system. Remember that the better the system you buy now, the more STCs you will gain.


Written by M Eduard

M. Eduard was born and raised in San Francisco, CA. Eduard spent his MBA summer internship at Sungevity, a residential solar energy retail company in Oakland, CA. He started this website to share his knowledge about renewable energy.