What would solar do for your power bill?
Thirty seconds to an honest, indicative answer. Conservative assumptions, all of them disclosed below the results. The real model is built from twelve months of your bills.
Your indicative numbers
Conservative, ex GST, modelled not promised
System size
69 kW
Sized to your daytime load
Installed cost
$108,823 to $148,646
Confirmed with certified installers
Investment Boost, year one
about $7,209
A 20% immediate tax deduction, worth this in cash at the 28% company rate. Not a discount.
Estimated annual saving
$18,779 to $22,257
80% of generation used on site
Indicative payback
4.5 to 7.5 years
Net of the Investment Boost benefit
Asset life
25+ years
Panels keep producing long after payback
ASB Smart Solar Loan: 0% for 5 years
Your current bill
$4,000/month
Loan repayment
$2,146/month
Estimated saving
$1,710/month
Reverts to a floating business rate after five years.
On these numbers the monthly repayment of $2,146 sits at or below your current bill of $4,000 while the loan runs, and the power keeps getting cheaper after it ends.
How this is modelled (assumptions v2026-06-v3)
- Power valued at $0.25 to $0.30/kWh ex GST (savings are never valued at the top of the commercial tariff range).
- Export credited at $0.08/kWh, the conservative end of current buy-back rates.
- Installed cost interpolated from 30 kW ($1,800 to $2,600/kW) down to 500 kW ($1,100 to $1,500/kW), 2025/26 working ranges.
- Central Otago and Queenstown Lakes yield modelled at 1260 kWh per kW per year.
- Self-consumption capped by your daytime usage profile and held below typical vendor claims; sizing targets 90 percent of daytime load.
- Investment Boost stated as the year-one cash value of the 20 percent immediate deduction at the 28 percent company rate. It is a tax timing benefit, not a discount.
- No power price escalation and no panel degradation in simple payback; omitting escalation outweighs degradation, so the net effect is conservative.
Indicative only; not financial or tax advice. The feasibility study models your site from twelve months of actual bills.
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