From "how much power do we use" to a parts list you can price in the index or the builder, with the New Zealand rules on what you may do yourself and what the law reserves for a licensed electrician. It is written for NZ homes, cabins and vehicles. It is general information, not advice about your house. Every rule is cited so you can read the source; the research notes behind this page carry the full citations and mark what could not be verified.
| Grid-connected, no battery | Hybrid (grid + battery) | Off-grid | |
|---|---|---|---|
| What it does | Panels feed the house, surplus exports to the grid | As left, plus a battery holds daytime surplus for the evening | No grid: panels, battery and inverter carry everything |
| Core parts | Panels, grid-tie inverter, mounting, isolator, cable, monitoring | Panels, hybrid inverter, battery, mounting, isolator, cable, monitoring | Panels, MPPT charge controller, battery bank, inverter or inverter/charger, fusing, monitoring |
| Typical NZ home | 3 to 6 kW; new installs now average around 6 kW | 5 to 10 kW with 5 to 15 kWh | Sized to load and winter sun |
| Who wires it | Licensed electrician; high-risk work, inspected | Licensed electrician; high-risk work, inspected | Extra-low-voltage DC (under 120 V DC) with no 230 V side is not prescribed work; anything at 230 V AC is |
| Lines company approval | Yes, before export | Yes, before export | No |
Daily use. Your bill or your retailer's app shows kWh per month or year. NZ homes average about 7,000 kWh a year, roughly 20 kWh a day (EECA, BRANZ Level); all-electric homes with heat pumps and a spa run 25 to 40.
Yield. No official NZ table of kWh per kW by city exists; NIWA's SolarView gives a per-address estimate, which is the number to use if you want to be exact. Modelled figures at optimal tilt (PVGIS, 2005 to 2023) run from about 1,140 kWh per kW a year in Invercargill through 1,230 Dunedin, 1,290 Hamilton, 1,340 Christchurch, 1,360 Nelson, 1,390 Auckland and Tauranga, to 1,430 Wellington. A real roof pitched and oriented as it happens to be makes 5 to 15% less than that; the builder applies a 10% roof factor. North is best; east or west costs 10 to 20%; shade costs far more than any panel spec makes back.
Array size. Daily use × 365 ÷ yield = kW of panels to make over a year what you use. 20 kWh a day in Wellington: 20 × 365 ÷ (1,430 × 0.9) ≈ 5.7 kW, or 13 × 440 W panels. EECA's own examples: 7 panels 3.5 kW with a 3 kW inverter, 12 panels 5.5 kW with 5 kW, 24 panels 10 kW with 9 kW; a 5 kW system covers "around 50 to 80%" of an average all-electric 3-person household (EECA). Roof area: about 35 m² for 5 kW, 70 m² for 10 kW.
Inverter size. Arrays are routinely 1.2 to 1.33× the inverter's AC rating (6.6 kW of panels on a 5 kW inverter is the classic pairing) because panels rarely reach nameplate. Since 11/05/2026 lines companies must offer a default export limit of 10 kW where feasible, or a dynamic limit that is 10 kW when the network is not congested (Electricity Authority); the old 5 kW single-phase default still applies on some networks and during congestion, so check yours before sizing above 5 kW.
Battery size (hybrid). Batteries are for the hours after sunset. Take the share of your daily use that happens then (50 to 70% for a working household), multiply by daily use, divide by 0.9 for round-trip losses. 20 kWh × 60% ÷ 0.9 ≈ 13 kWh usable. Batteries come in modules of 2.5 to 5 kWh that stack, so round up to whole modules.
Off-grid. Size for winter, not the annual average: a winter day yields about half the annual mean per kW. Then: system voltage (12 V for very small loads, 24 V for a cabin or van, 48 V above roughly 2.5 kWh a day so currents stay sane); battery Ah = daily Wh × days of autonomy ÷ (V × 0.8) for lithium; MPPT amps = array W ÷ V × 1.25; inverter continuous watts at or above the biggest set of loads you will run at once. A kettle alone is 2,000 W. BRANZ's rule: tilt panels at latitude plus 10° for off-grid (winter bias), latitude minus 10° for grid-tied.
Panels. Current residential modules are 400 to 500 W N-type. Price per watt is the fair comparison and the index shows it. Bifacial gains nothing on a roof. Expect a 10-year product warranty as the floor and 25 years from many makers, with a separate 25-year performance warranty (EECA warranty baselines).
Inverter. For the streamlined connection process it must be installed to AS/NZS 4777.1 and carry a Declaration of Conformity to AS/NZS 4777.2:2020 from an IANZ-recognised lab; in practice Vector, Wellington Electricity and Unison send you to the Australian Clean Energy Council approved-inverter list and Orion keeps its own list. Decide hybrid vs plain grid-tie now: adding a battery to a non-hybrid inverter later means a second inverter. Match phase to your supply. Warranties: 5 years is the floor for string inverters, 10 for microinverters; 10 to 15 is common.
Battery. LFP (LiFePO4) chemistry, 10-year warranties are the norm. Batteries are tied to inverter families (Sungrow with Sungrow, BYD or Pylontech per a compatibility list); check the inverter maker's list before buying the cheapest module. Installation follows AS/NZS 5139 (location, clearances, mechanical protection); batteries do not go in habitable rooms or ceiling spaces.
Mounting. Rails, roof interfaces (tin, tile or Klip-Lok clips) and clamps rated for your wind zone. Roof penetrations are the leak risk; use the manufacturer's flashing system. See §4 on building consent.
Isolation and protection. AS/NZS 5033:2021 (the edition cited in the regulations) no longer requires a rooftop DC isolator; one isolator at the inverter is normal. DC surge protection where the array is remote from the inverter. Cable is 4 or 6 mm² PV1-F/H1Z2Z2; connectors genuine MC4 or Staubli, never mixed brands.
Monitoring. A CT clamp on the switchboard turns the inverter app from "what I generated" into "what I used vs exported", which is the number that decides whether a battery is worth it.
Solar work in NZ sits under the Electricity (Safety) Regulations 2010 (ESR). In short:
Distributed generation up to 10 kW is governed by Part 6 of the Electricity Industry Participation Code (Electricity Authority):
Export rates published on retailer pages in August 2026 (check the page on the day; most are quoted excluding GST): Meridian 15c, 24c winter peak; Powershop 13c, 23c winter peak; Genesis and Frank 12.5c; Mercury 11.1c flat or seasonal time-of-use up to 20.4c; Octopus 19c peak / 14c off-peak (23c / 10c on its battery plan); Ecotricity 21c peak / 16c off-peak; Electric Kiwi 23c on one plan (incl GST); Contact does not publish a rate. From 01/07/2026 the large retailers must offer at least one time-varying export rate, and from 01/04/2026 lines companies pay a rebate for export at peak times (EA).
Import prices are roughly double the flat export rates. That gap is the whole battery case: every kWh shifted from export to self-use is worth the difference. A battery pays back sooner in a house that is empty in the daytime and heavy in the evening, slower where someone is home all day. EECA's June 2025 modelling put system returns at 6 to 14% a year without a battery, with batteries adding 1 to 2 points (EECA); the winter-peak export rates above have improved that since.
EECA's indicative installed prices (December 2025): 3 kW $8,500; 5 kW $11,500; 10 kW $20,000; adding a battery $5,000 to $15,000 (EECA). Market surveys in 2026 sit a little under that at around $2 per watt installed. Compare an installer's quote against the parts total from the builder plus labour, certification, inspection and the lines-company fee; if the gap is large, ask which line carries it.
Print or copy the builder's parts list. Ask each installer:
The Consumer Guarantees Act applies to anything you buy from a NZ trader regardless of the manufacturer's warranty; gear imported directly leaves you no NZ trader to claim against.