Solar that pays on your irrigation, chilling and effluent loads
Design, financing and installation management for Canterbury dairy farms. Milking runs before dawn, so we size solar to the loads that run in daylight, and prove it on your bills first.
The short answer
Solar pays on Canterbury dairy farms with daytime load: irrigation and effluent pumping, milk chilling and water heating, not the pre-dawn milking peak. A typical 30 kW shed system costs $54,000 to $78,000 installed in 2026, and EECA's Kaiwaiwai case shows a 54 kW array saving $17,000 to $20,000 a year.
Canterbury runs the largest dairy herd in the country, and its farms carry the daytime loads that make solar work: irrigation pumping, milk chilling, effluent systems and water heating. Milking itself peaks before dawn, so the honest solar case is built on those all-day loads, not the shed. Where they are present, and in Canterbury they usually are, the numbers stack.
We are not an installer. Involve Energy models the system against your own bills, arranges the financing stack and project-manages SEANZ-certified local crews through to commissioning, so you get an owned asset, an independent model and one point of accountability.
Where solar pays on a Canterbury dairy farm
- Irrigation and effluent pumping: the best solar match on the farm, running hardest in daylight through the dry months.
- Milk chilling and refrigeration: compressors cycle all day, every day of the season.
- Water heating: shift cylinder heating onto daytime timers and it becomes a solar load.
- The wider connection: pump sheds, workshops and dwellings on the same ICP soak up generation that would otherwise export.
The full picture, including the pre-dawn milking caveat and a worked EECA example, is in our guide to solar for dairy farms.
How it works
- 1
Feasibility
Send twelve months of power bills, ideally half-hourly data. We model system size, generation against your actual load, self-consumption, cost, savings and payback on your numbers, not industry averages.
- 2
Financing
We apply the Investment Boost deduction and match the remainder to the best available green or interest-free business lending, sized so the repayment sits at or below your current bill wherever the numbers support it.
- 3
Installation
Certified local crews install and commission the system. We manage the lines company approval, the electrical certification and the programme around your milking and irrigation calendar.
- 4
Monitoring
Once live, we watch performance, flag anything underperforming and report your actual savings against the model, year after year.
Start with a conservative estimate in the calculator below, then send a year of bills for the half-hourly version. The Investment Boost and financing options are explained in full in the guides.
What the numbers look like
| System size | Indicative installed cost | Indicative annual saving | Indicative payback |
|---|---|---|---|
| 30 kW | $54,000 to $78,000 | $7,000 to $8,000 | 6 to 10.5 years |
| 60 kW | $98,000 to $135,000 | $14,000 to $17,000 | 5.5 to 9 years |
| 100 kW | $140,000 to $180,000 | $24,000 to $28,000 | 4.5 to 7 years |
| 250 kW | $275,000 to $375,000 | $60,000 to $70,000 | 3.5 to 6 years |
Proof it works here
Kaiwaiwai Dairies
Kaiwaiwai Dairies in the Wairarapa runs a 54 kW ground-mounted array that cost about $110,000 and saves $17,000 to $20,000 a year, a five and a half to six and a half year payback. More than 90 percent of generation is used on site across irrigation, effluent and chilling; export income is only about $267 a year. Figures as published by EECA.
- System
- 54 kW
- Installed cost
- $110,000
- Annual saving
- $18,500
- Payback
- 6 years
Source: EECA case study
Run your own numbers
Conservative assumptions, fully disclosed, no contact details needed.
Your indicative numbers
Conservative, ex GST, modelled not promised
System size
54 kW
Sized to your daytime load
Installed cost
$89,794 to $125,589
Confirmed with certified installers
Investment Boost, year one
about $6,031
A 20% immediate tax deduction, worth this in cash at the 28% company rate. Not a discount.
Estimated annual saving
$12,895 to $15,163
70% of generation used on site
Indicative payback
5.5 to 9 years
Net of the Investment Boost benefit
Asset life
25+ years
Panels keep producing long after payback
Bank green business loans: 1.0% for 3 years
Your current bill
$4,000/month
Loan repayment
$2,257/month
Estimated saving
$1,169/month
The loan caps at $80,000, so the repayment shown covers that portion; the remainder is financed separately. The full financing stack is part of the feasibility study.
On these numbers the monthly repayment of $2,257 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.
- Canterbury yield modelled at 1200 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.
Get these numbers checked properly
The real model is built from twelve months of your bills. Send your details and we will do it for you; we reply within one working day, no obligation.
Straight answers
Is solar worth it on a Canterbury dairy farm?
Often, where there is real daytime load. Milking peaks before dawn, so solar pays on irrigation and effluent pumping, milk chilling and water heating instead, and Canterbury farms tend to run all three. A half-hourly analysis of your year of usage gives the honest answer before you spend anything.
Does solar pair well with irrigation pumping?
Yes, it is the best-matched load on most Canterbury farms. Pumps run hardest through daylight in the dry months, exactly when panels produce most. Irrigation including electricity cost around 31 cents per kilogram of milk solids on the average irrigated Canterbury farm in 2020-21 (Farmers Weekly), and power prices have risen since.
What size system does a dairy shed need?
Installers commonly quote around 30 kW for a typical rotary shed, roughly 55 to 70 panels, producing 150 to 200 kWh a day in the peak milking month. Irrigation-heavy farms justify far larger arrays. The right size follows your daytime load, not the shed, which is what the feasibility study works out.
How do Canterbury farmers pay for solar?
Most stack the Investment Boost tax deduction (20 percent immediate deduction on new assets) with rural green lending. ASB has offered a Smart Solar Loan at 0 percent for five years on up to $150,000 of on-farm solar and battery for rural customers; dated offers like this lapse and renew on bank timetables, so we only ever show what is live on the day you run the numbers.
What about winter, when the cows are dried off?
South Island winter output runs around 40 to 60 percent of summer, which matches dairying reasonably: the heavy irrigation and chilling months are also the high-sun months. The annual model we publish accounts for the full seasonal shape month by month rather than averaging it away.
See your farm's numbers before you commit
Send a recent power bill and we will model system size, cost, savings and payback against your actual usage, the pre-dawn caveat included. Independent, no obligation, yours to keep.