Source
https://www.eeca.govt.nz/assets/EECA-Resources/Research-papers-guides/Understanding-the-value-of-residential-solar-PV-and-storage-in-NZ.pdf — original source (opens in a new tab; the file is not redistributed)
EECA — the value of residential solar PV and storage in NZ (OT_104)
Definitive recent NZ residential solar + storage value study
EECA modelling of half-hourly demand and solar across four NZ cities under multiple price pathways. Its §7.1 self-sufficiency analysis is the strongest recent NZ primary for why off-grid autonomy is expensive, and it directly validates the model’s grid-tied design premise (D18/D37) and 3-slice temporal logic (D19).
Summary
EECA models the economics of residential solar PV and battery storage across Auckland, Wellington, Christchurch and Queenstown at half-hourly resolution under various distribution/retail price pathways. Solar PV delivers internal rates of return of ~8% (up to 11–12%), best at 3–5 kW-ac, comparable to utility-scale. Its most NI-relevant contribution is a quantified account of the cost of self-sufficiency: because NZ demand and solar are seasonally inverse (demand peaks in winter when solar is lowest), meeting annual needs from solar+storage alone requires impractically large systems — which is why, in EECA’s words, off-grid systems “almost always require a backup fossil fuel powered generation.” This is direct empirical support for the model’s grid-tied outage reserve (D37) and grid-import-counts-out rule (D18).
Key claims
- claim: "THE COST OF SOLAR-ONLY SELF-SUFFICIENCY (Table 18, verbatim). For a Cluster 0 8,000 kWh/pa ICP, the solar PV capacity needed to meet annual energy needs assuming storage over the period (no losses): YEAR (seasonal storage) - Auckland 5, Wellington 5, Christchurch 5, Queenstown 4 kW-ac ('would require a very large battery capable of storing hundreds of kWh over a long period'); MONTH - 24/14/13/12 kW-ac; WEEK - 45/31/25/19 kW-ac; DAY - 178/123/167/177 kW-ac. Conclusion (verbatim): 'it is very expensive to be self-sufficient with solar PV and battery alone, and/or requires substantial changes to energy use... This is why off-grid power systems almost always require a backup fossil fuel powered generation and some other form of heating... it illustrates why the connection to the electricity network is so important.'"
source_location: "Section 7.1 Solar PV and self-sufficiency; Table 18 (p.100)"
- claim: "SEASONAL INVERSE CORRELATION (Section 7.1, verbatim). NZ household demand and solar generation are 'typically inversely correlated; household energy demand is usually lowest in the summer when solar generation is highest, and household energy demand is usually highest in the winter when solar generation is lowest' - the structural reason self-sufficiency requires seasonal-scale storage."
source_location: "Section 7.1; Figure 39 (Christchurch demand vs solar by month)"
- claim: "GRID CONNECTION IS THE ECONOMIC BACKBONE (Section 7.2, verbatim). 'solar PV does not match most electricity consumption in New Zealand, which follows a pattern of higher consumption in winter particularly during peak periods'; solar PV alone does not limit peak demand. The key NZ economic benefit is distributed solar + battery (with suitable time-of-use prices) reducing distribution/transmission/peaking investment - not autonomy."
source_location: "Section 7.2 The importance of a connection to the electricity network"
- claim: "SOLAR PV ECONOMICS (Executive Summary, verbatim). Residential solar PV can be an 'investment that can provide internal rates of return above 8% and sometimes as high as 11-12%'; the solar PV capacity providing the maximum rate of return is '3 to 5 kW-ac, depending on annual [consumption]'; returns are 'comparable to utility-scale solar' and improve with higher annual electricity consumption. Modelling is half-hourly across Auckland, Wellington, Christchurch and Queenstown under multiple price pathways."
source_location: "Executive Summary; Sections 4-6"Neobiome Intelligence relevance
This is the strongest recent NZ primary evidence for the model’s grid-tied design choices. Three direct ties:
- D37 (grid-tied outage reserve) + D18 (grid-import-counts-out): Table 18 and the “off-grid… almost always require a backup fossil fuel powered generation” conclusion are direct empirical support for treating a genuine off-grid autonomy target as expensive/impractical and for the diesel-reserve backstop — corroborating CR_030 with a stronger, more recent, NZ-specific half-hourly study.
- D19 (3-slice temporal model): the seasonal inverse correlation (and the solar-vs-evening-peak mismatch) is exactly the coincidence the 3-slice logic exists to capture — annual averaging would hide it.
- Economics: the 8–12% IRR band and the 3–5 kW-ac optimal-return capacity are NZ-specific sanity checks for the engine’s solar sizing and payback/NPV outputs.
Feeds d01_renewable_energy_storage.
Research targets
Documents to retrieve
- None new. Appendix One (per-region half-hourly detail) is already OT_061.
Research gaps
- ⚠ Cover-date/version discrepancy (June 2025 vs the RT’s “2024”) — same study, confirm which edition is canonical if precisely citing.
Notes
Primary — the EECA parent report, read verbatim. data_quality: verified. Single-file (the Appendix One is already OT_061, ingested 2026-06-09 — not re-filed here). Retrieved from eeca.govt.nz (authoritative NZ-govt PDF; not AI-prepared, so no retrieval-provenance block). The off-grid/island LCOE dimension is separately held by LIT_033 (Rakiura) — this report is the grid-connected residential-value counterpart.
Connections
Links to
Sources (3): CR_030 · LIT_033 · OT_061
EDT domains (1): D01: Renewable Energy & Storage Systems
Referenced by
Sources (2): LIT_073 · LIT_084
EDT domains (1): D01: Renewable Energy & Storage Systems