CALCULATING YOUR FEED-IN TARIFF

Your Feed-in PEA on a time of use tariff

There are three key differences in a time of use tariff compared to the flat network tariff:

1. It will consider if the time interval is in peak, off-peak or shoulder period of your assigned network tariff,
2. where there are stepped rates, it will use the first network rate, and
3. any demand charges will be billed directly as a separate charge on your account.

In order to determine your Feed-in PEA on a time-of-use tariff, we first need to determine your Customer Feed-in PEA.

We determine this by multiplying the total price (which is the sum of the wholesale price and the network price, updated every 5 minutes) by your electricity export for that period. We do this for the whole billing month.

Let’s say the wholesale price was 1 c/kWh during the first price period and your export was 4 kWh.

We’d multiply these together and repeat this multiplication every time the wholesale price changed (i.e. every five minutes). We’d then again divide the total by your total electricity export for each price period.

This value is called the Load Weighted Average Price (LWAP).

Below is an illustrative example (note that price intervals reset every 5 minutes and a typical billing period is about a month, so this is a very simplified example):

In this example, the relevant calculation would be [ (7 x 0) + (1 x 4) + (7 x 3) + (16 x 0)] / (0 + 4 + 3 + 0) = 3.6 c/kWh.

We then need to determine your Time Weighted Average Price (TWAP). We calculate this by adding up the total price for each price period in the billing month, then dividing the total by the number of price period for the billing month.

In the above example, this would result in a calculation of (7+ 1 + 7 + 16) / 4 = 7.8 c/kWh.

To get your Customer Feed-in PEA we subtract these two figures from one another. In this example your CFPEA would be 3.6 c/kWh – 7.8 c/kWh = – 4.2 c/kWh.

Now that we have your Customer Feed-in PEA, we need to subtract the Benchmark Feed-in PEA from it to get your actual, final, billing period Feed-in PEA (that’s the amount that is added or subtracted to the Feed-in Tariff in your bill)

If your Customer Feed-in PEA is less than the Benchmark Feed-in PEA, your Feed-in PEA that month would reduce your FiT rate for that bill, and in some cases can result in additional charges if your home export is very inefficient.

Using the same examples from above, with a FiT rate of 4.9 c/kWh and an example Feed-in PEA of –4.2 c/kWh, your FiT rate would be calculated as follows:

CFPEA – BFPEA = FPEA

or

-4.2 c/kWh – (- 6.9 c/kWh) = 2.7 c/kWh

In this example, your Feed-in PEA would be 2.7 c/kWh. This would mean you’d receive additional credit to your FiT rate for that month, which would be calculated as follows

FiT + FPEA = FiT Rate

or

4.9 c/kWh + (2.7 c/kWh) = 7.6 c/kWh

If your Customer Feed-in PEA is below the Benchmark Feed-in PEA, your Feed-in PEA that month would be negative, decreasing your FiT rate in that month’s bill.

Using the same examples from above, with a feed in tariff of 4.9 c/kWh and an example Feed-in PEA of -10.1 c/kWh, your FiT rate would be calculated as follows:

CFPEA – BFPEA = FPEA

or

-10.1 c/kWh – (- 6.9 c/kWh) = -3.2 c/kWh

In this example your PEA would be -3.2 c/kWh, meaning you’d receive a decrease to your FiT rate for that month. This would be calculated as follows:

Base rate + PEA = electricity price

or

4.9 c/kWh + (- 3.2 c/kWh) = 1.7 c/kWh