Transpower, as the System Operator, is responsible for publishing the medium-term security of supply assessment (SOSA) annually. This assessment uses forecasts of electricity supply and demand to assess the ability of the electricity system to meet New Zealand's needs over the decade ahead.
The analysis looks at existing generation as well as planned generation at different stages of the development process to determine whether there is enough electricity generation in the system to meet total demand across the country under a range of supply and demand scenarios, such as demand rising much faster than forecast or major industrial users ceasing operations.
It calculates both energy and capacity margins. Energy margins assess the adequacy of generation plus HVDC transmission capacity between the North and South Islands to meet expected electricity demand across the winter months under different supply and demand conditions. The capacity margin assesses the adequacy of generation and HVDC transmission capacity to meet peak winter North Island demand.
These margins are compared against security standards set by the Electricity Authority in the Security Standards Assumptions Document (SSAD).
Generators, other market participants and investors use the annual assessment to inform decision-making over the short- and medium-term, including about development of new generation.
Security of Supply Assessment 2023
The 2023 Security of Supply Annual Assessment is published below:
Updated SOSA Information
MBIE have updated forecasts of gas production and gas reserves. These forecasts are used as inputs to the annual Security of Supply Assessment, and the updates impact the results of some sensitivities in this analysis. The following document shows the impact these changes have on the 2023 SOSA.
Previous annual assessments
- 2024
Review of the security of supply annual assessment reference case assumptions and sensitivities
In Nov-Dec 2023 we asked for comment on the Reference Case and Sensitivities we use for the Security of Supply Annual Assessment. Linked below is the consultation document and submission documents of the responses we received.
Consultation Document
2024 SOSA Reference Case and Sensitivities Consultation Document
Submissions Received:
2024 RCA and S submission - MEUG.pdf (PDF 223.06 KB)2024 RCA and S submission - ERA.pdf (PDF 186.5 KB)2024 RCA and S submission - Nova Energy.pdf (PDF 178.62 KB)2024 RCA and S submission - Bryan Leyland.pdf (PDF 155.69 KB)Summary of Submissions
- 2023
Draft Security of Supply Assessment
In May 2023 we asked for feedback on the draft 2023 SOSA the submission period closed on 26 May 2023, please go to the Invitation to Comment: Draft Security of Supply Assessment page for further details.
Review of the security of supply annual assessment reference case
In December 2022 we asked for comment on the Reference Case and Sensitivities we use for the Security of Supply Annual Assessment. Linked below is the consultation document and a document containing the summary of responses we received.
- 2022
Security of Supply Assessment 2022
The 2022 Security of Supply Annual Assessment is published below:
2022 SOSA - Final Cover Note - Final Version.pdf (PDF 159.06 KB)2022 SOSA - Final Report - (Revised) Final Version.pdf (PDF 4.63 MB)2022 SOSA - Final Summary of Submissions - Final Version.pdf (PDF 272.35 KB)2022 SOSA - Final Supplementary Data - Final Version.xlsx (XLSX 2.94 MB)2022 SOSA - Final Appendices - Final Version.pdf (PDF 4.41 MB)Review of the security of supply annual assessment reference case
In February as part of the 2022 Security of Supply Annual Assessment we asked for comment on the Reference Case and Sensitivities we use for the Security of Supply Annual Assessment. The document linked below contains the comments provided by industry participants and our responses to them.
- 2021
The 2021 Security of Supply Annual Assessment is published below:
2021-10 Final ASA Report Cover Note.pdf (PDF 337.43 KB)2021-10 ASA Final Report.pdf (PDF 1.91 MB)2021-10 ASA Final Appendices.pdf (PDF 2.22 MB)SoS Annual Assessment 2021 - Final Supplementary Data.xlsx (XLSX 417.88 KB)Submissions
Contact Energy submission - 2021 SoSAA.pdf (PDF 193.23 KB)Energy Resources Aotearoa submission - 2021 SoSAA.pdf (PDF 374.4 KB)Gas Industry Co submission - 2021 SoSAA.pdf (PDF 274.74 KB)Nova Energy submission - 2021 SoSAA.pdf (PDF 214.03 KB)OMV submission - 2021 SoSAA.pdf (PDF 311.84 KB)Stephen Drew submission - 2021 SoSAA.pdf (PDF 176.29 KB)Vocus submission - 2021 SoSAA.pdf (PDF 161.78 KB)- 2020
The 2020 Security of Supply Annual Assessment is published below:
Final SoS Annual Assessment 2020 report AS PUBLISHED.pdf (PDF 5.59 MB)SoS Annual Assessment 2020 - Supplementary Data.xlsx (XLSX 91.45 KB)Submissions
- 2019
The 2019 Security of Supply Annual Assessment is published below:
Cover note for 2019 Security of Supply Annual Assessment.pdf (PDF 507.53 KB)SoS Annual Assessment 2019 report.pdf (PDF 2.65 MB)- 2018
The 2018 Security of Supply Annual Assessment is published below:
SoS Annual Assessment 2018 .pdf (PDF 1.86 MB)SoS Annual Assessment 2018 - Supplementary Data.xlsx (XLSX 59.06 KB)- 2017
The 2017 Security of Supply Annual Assessment is published below:
SoS Annual Assessment 2017.pdf (PDF 2.16 MB)