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NZ homeowner benchmark tool
Solar Offer Reality Check
This single-offer tool helps a homeowner benchmark a solar quote against broad New Zealand public guidance. It is designed to help users ask good questions if an offer appears to rely on unusually high generation, unusually high self-consumption, or unclear export assumptions.
What this tool checks
- Adjusted $/kWp using a battery-cost allowance when storage is included
- Annual generation per kWp against a broad NZ roof-performance range
- Self-consumption realism against a broad household-use benchmark
- Export limit, panel efficiency, and inverter sizing for extra sense-checking
Benchmark basis: This tool uses broad sanity-check bands informed by EECA home solar guidance and example systems, NIWA SolarView solar-resource guidance, and Electricity Authority export-limit guidance. These are homeowner screening ranges, not exact guarantees for a specific roof.
2. Reality-check summary
One offer benchmarked against NZ public guidanceArray size
——Adjusted $/kWp
—Battery-adjusted when storage is enteredGeneration intensity
—Quoted annual generation per kWpSelf / export
—Export is the remainder of generationEstimated annual value
—Using your import and export valuesEnter the offer details
The tool will highlight where the offer looks aligned with broad NZ norms and where you may want supporting evidence.
Rotary Dial 1 — Adjusted price per kWp
The green zone is a broad NZ solar-only benchmark zone. If a battery is included, a standard battery allowance is removed before calculating $/kWp.
Offer result: —
—
benchmark zone
$1,500Green zone: $2,000–$2,900$4,000
For solar-only systems, EECA example systems imply a broad residential range around $2,000–$2,900 per kWp. If a battery is included, this tool first subtracts a standard battery allowance.
Rotary Dial 2 — Annual generation per kWp
The green zone is the broad rooftop-output band for the selected NZ roof/location type.
Offer result: —
—
selected roof band
700Green zone: 950–1,3501,600
Choose the roof/location band above to match a conservative, typical or sunny NZ roof. The quote should usually sit somewhere within, or close to, that band.
Rotary Dial 3 — Self-consumption realism
The green zone is the broad self-consumption band for your daytime-use profile and battery setting.
Offer result: —
—
selected use profile
0%Green zone: 35–60%100%
If a quote assumes much higher self-consumption than normal, it can make payback look better. Ask how the figure was calculated and whether any manual override was used.
Questions or flags raised
- Enter the quote values to begin.
Panel efficiency fact-check
Typical modern residential panels often sit around the low-20% range. Always compare with the manufacturer datasheet.
Export-limit sensitivity
If the offer depends heavily on exports, the approved network export limit matters. If it is not stated, ask for it in writing.
Inverter sizing check
A moderate DC/AC oversize can be normal, but if the array is much larger than the inverter the quote should explain clipping assumptions.
!
This tool is designed to be neutral
It does not say another installer is wrong. It simply asks whether the quote sits within a broad NZ reality range and whether the assumptions appear to have been clearly disclosed.
3. Questions to ask if the offer looks too good
Use these to keep the discussion factual and fair- Can you show the design report with annual generation, kWh/year per kWp, self-consumption, export percentage, tariffs and export limit?
- Has the self-consumption percentage been manually overridden? If yes, what is the reason?
- Can you provide the exact solar panel datasheet showing wattage and efficiency?
- What export limit has the network approved for this property, and is export curtailment reflected in the savings model?
- Does the quote assume the household will shift more electricity use into the daytime?
- If a battery is included, what operating assumptions were used to increase self-consumption?
- If the array is oversized relative to the inverter, how much clipping has been allowed for in the annual generation figure?
- Can you provide the same quote using standard assumptions, without manual overrides, so I can sense-check it against NZ public guidance?
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Suggested homeowner wording
“I’m not saying your quote is wrong — I’m just checking whether the generation, self-consumption and export assumptions sit within normal NZ ranges and whether they’ve been fully explained.”
Public guidance references for the web page copy: EECA home solar pages and example systems, NIWA SolarView guidance for rooftop solar resource, and Electricity Authority guidance on default 10 kW export limits for straightforward small-scale residential distributed generation.