In this introduction, you will find information on the vesting contract credits and debits formula, the variables in the formula and how the various variables in the formula are calculated or obtained. The purpose is to provide you with an understanding of the formula, its variables and the derivation of the variables, and how you can check the vesting contract credit/debit shown in your bill.
Vesting contract credit and/or debit are calculated using the following formula:
Vesting contract credit/debit = ∑(Vesting Rate x Vested Quantity) where:
Vesting Rate = VCRPhh - PRPhh
Vested Quantity = Adjusted Energyhh x VHPhh
Getting the necessary data for the calculation
The following explains where the necessary data required in the formula can be obtained or calculated.
VCRPhh is the Vesting Contract Reference Price; this is the electricity price used in the vesting settlement and is calculated by the Energy Market Company (EMC). Half-hourly VCRPhh measured in $/MWh can be obtained from EMC's website www.emcsg.com.
PRPhh is the Payment Reference Price; this is the price consumers pay for their vested quantity of their electricity consumption. PRPhh ($/MWh) can be obtained from the Open Electricity Market website. PRPhh is updated every quarterly and is constant for each half-hour period in that quarter.
3. Adjusted Energyhh
Adjusted Energyhh is the half-hourly electricity consumption adjusted with the transmission loss factor and can be requested from SP Group by you or your retailer on your behalf by:
- Contacting our Market Support Services Operation Department via email at firstname.lastname@example.org or
- Calling our hotline at 1800 233 8000.
Please note that the Adjusted Energyhh does not include any metering data adjustments if there are any. When you or your retailer sends a request to SP Group for your half-hourly consumption data, SP Group shall forward to you the vesting contract credit/debit calculated for the metering data adjustments of the past month together with the half-hourly consumption data.
VHPhh is the Vesting Hedge Proportion; this is the percentage of contestable consumers' electricity consumption that is covered by vesting contracts and for which consumers pay the PRPhh. VHPhh varies every half-hourly and is expressed in the form of percentage (%).
There are nine (9) VHPhh, each corresponding to one segment of the three periods of Peak, Off-peak and Shoulder for Sundays and public holidays, Saturdays and weekdays. The VHPhh can be obtained from the Open Electricity Market website. The VHPhh is updated quarterly.
Below is an example of the VHPhh Table:
|Sunday and Public Holiday||0||24.67||37.31|
Each half-hour has its particular VHPhh. In order to apply the correct VHPhh percentage for a particular half-hour, you need to refer to the Day Profile Table which can be obtained from the Open Electricity Market website (please see illustration below). The Day Profile Table shows the applicable VHPhh for each half-hour with the first half-hour (period 1) starting at 00.01 am and ending at 00.30am, period 2 from 00.31 to 01.00 am etc.
5. Sample Day Profile Table
To select the correct VHPhh for a half-hour period, identify the correct VHPhh segment from the Day Profile Table. For example for the period 10.01am to 10.30am on 1 January 2004, it corresponds to period 21 for a public holiday in the Day Profile Table. The corresponding VHPhh segment for this period is "Off-Peak Sunday / Public Holiday" and the VHPhh from the VHPhh Table for "Off-Peak Sunday / Public Holiday" is 24.67%.
6. Vested Quantity
The Vested Quantity is calculated for the half-hour period (10.01am to 10.30am on 1 January 2004) by multiplying the Adjusted Energyhh of that half-hour period (10.01am to 10.30am on 1 January 2004) by VHPhh.
The formula is given below:
Vested Quantity = Adjusted Energyhh x VHPhh
7. Vesting Rate
The Vesting Rate is calculated for the half-hour period (10.01am to 10.30am on 1 January 2004) by the following formula:
Vesting Rate = VCRPhh - PRPhh
8. Calculating the Vesting Contract Credit/Debit
The vesting contract credit/debit for each half-hour period is calculated using the formula:
Vesting contract credit/debit for one half-hour period = Vesting Rate x Vested Quantity
The vesting contract credit/debit for one month (for example for January 2004) will be the sum of all the vesting contract credit/debit for all the half-hour periods for the month.
Vesting contract credit/debit for January 2004 = ∑(Vesting Rate x Vested Quantity)
Please note that both VCRPhh and PRPhh are presented as dollars per MWh ($/MWh) and so the vesting rate is also in $/MWh. Your consumption data (and hence the vested quantity) is likely to be in kWh; to convert the vesting rate to $ per kWh divide the vesting rate by 1000 before calculating the vesting contract credit/debit.
9. Checking the Vested Quantity on the Bill
The Vested Quantity that appears on the bill is the total vested quantity (in kWh) for the entire billing period. To calculate the Vested Quantity, apply the formula in Paragraph 6 for each half-hour period in the entire billing period. The total will be the Vested Quantity for the entire billing period that is reflected in the bill.
Please note: if there are adjustments to the metering data, the Vested Quantity for the adjustments will be shown as an additional line item in the bill. Please see illustration below:
The Vested Quantity calculated by the formula will not include the adjustments to the metering data. You can obtain the Vesting Quantity for the adjustments to the metering data from SP Group, please see Paragraph 3 above.
10. Checking the Vesting Rate on the Bill
The Vesting Rate that appears on the bill is the weighted average vesting rate (in $/kWh) for the entire billing period. It is calculated as follows:
- Divide each of the half-hourly vesting contract credits/debits calculated by the formula in Paragraph 8 by the total Vested Quantity for the entire billing period
- Add up the results of the calculation. The total gives the weighted average vesting rate which is reflected in the bill. Please note that this is not the rate used in the calculation of Vesting Contract Credit/Debit; it is displayed on the bill for reference only.
11. Checking the Vesting Contract Credit/Debit on the Bill
The Vesting Contract Credit/Debit that appears on the bill is the total vesting contract credit/debit (in $) for the entire billing period and is calculated as described in Paragraph 8 above. Please note that if there are adjustments to the metering data, the Vested Credit/Debit for the adjustments will be shown as an additional line item in the bill. Please see illustration in Paragraph 10 above.
12. Interpretation of the Vesting Contract Credit/Debit on the Bill
The Vesting Contract Credit/Debit may be positive or negative as a result of the calculation. A negative amount means it is a vesting contract debit and the consumer has to pay more for the vested portion. A vesting contract debit will therefore appear as a positive item in the bill with a positive vesting rate. Conversely, a negative vesting rate will result in a vesting contract credit and will appear negative in the bill, meaning there is a deduction from the amount the consumer has to pay.
An example of Vesting Contract Credit/Debit
The allocation of vesting contract credit/debit is calculated by the following formula:
∑(VCRPhh- PRPhh) x (Energyhh x TLF x VHPhh)
For a given half-hour period;
Energy = 5,000 kWh
TLF = 1.10
VHP = 0.50
VCRP = S$ 0.10 (per kWh)
PRP = S$ 0.08 (per kWh)
(VCRPhh- PRPhh) x (Energyhh x TLF x VHPhh) = (0.10-0.08) x (5000 x 1.10 x 0.50) = S$55
This is a vesting contract credit; the customer receives a refund of S$55 against his/her electricity payment for this half-hour period.
Note: This appears as a negative value on the bill - it is a credit to customer.
VCRPhh = Vesting Contract Reference Price
*PRPhh = Payment Reference Price
Energyhh * TLF * VHPhh = Vested Quantity
Energyhh = Energy consumed
TLF = Transmission Loss Factor
*VHPhh = Vesting Hedge Proportion; proportion of contestable consumption covered by vesting contract
*HPhh= Hedge Price to generators
*HQhh = Hedge Quantity allocated to the generator
*output components from VCC application
hh refers to a given half hour period
- EMA's Procedures for Calculating the Components of Vesting Contracts
- Regulated Supply Services Code
- Market Support Services Code