Government backing has pushed on-farm solar up the agenda for a lot of New Zealand farmers lately, and it has plenty of them taking a hard look at how they power the place. The appealing idea is that solar might now cover the entire operation and leave the generator sitting idle.
How true that turns out to be depends on two things: what you run, and when you run it. Get clear on those and the picture sharpens quickly.
The push towards renewable power hasn't skipped the farm gate. Through the Energy Efficiency and Conservation Authority (EECA), a demonstration programme co-funded solar and battery systems on farms around the country, covering setups from 30 kWp up to 500 kWp with support of up to $200,000 per farm.
Applications for that funding have since closed, but it did its job and got plenty of farmers thinking seriously about solar for the first time. EECA still runs a solar helpline and publishes independent guidance, so the interest is very much alive. A smaller power bill is an easy thing to want, though no amount of funding changes the one limitation that matters: the sun isn't always up when your farm needs power.
On a clear day, solar is hard to beat. Once the panels are installed and paid off, or subsidised, the electricity they generate can significantly reduce your power bill.
Daytime jobs like water pumping, milk cooling, running the workshop and keeping the shed lit are all well suited to it, and the savings stack up year after year. If most of your heavy power use happens while the sun is up, solar will pay you back handsomely.
Farms don't keep daylight hours, and your power demand won't politely wait for the panels to warm up. The moments that put real pressure on your setup tend to be the ones solar handles worst:
On its own, solar leaves a gap in every one of these. Batteries are supposed to fill them, though that comes at a price we'll get to shortly.
Getting a handle on your farm's peak power draw is the first step before committing to any system, solar or otherwise. AgriQuip's generator size calculator gives you a quick read on the capacity your operation needs.
Batteries hold your daytime solar so you can use it after dark, which sounds like the fix for everything until you see the quote. Storage is expensive, and the more days of independence you want, the steeper it gets.
Building a battery bank big enough to run a working farm through several sunless days in a row is a serious outlay, and the cost doesn't stop once it's installed. Most farm batteries last somewhere between 10 and 15 years, losing capacity the whole way, and replacing a bank that size is a bill you'll feel.
You can certainly put together a solar and battery system that keeps the farm running through most conditions. The trouble sits in that word "most". Sizing it to survive the genuinely bad stretches, the ones that would otherwise cost you production, pushes the price into territory that's hard to justify.
Plenty of farmers who opt for solar power keep a generator anyway, and there is sound reasoning behind it. A generator works in weather that flattens solar output, and it works at any hour.
A properly sized generator can power the whole farm on demand, give full output regardless of season, and cover the exact moments when solar or storage falls short. On a dairy operation where one missed milking carries a real dollar cost, that reliability tends to win the argument.
A properly sized generator gives you:
Treating solar and industrial size generators as competitors misses how neatly they fit together. Solar takes care of your routine daytime running costs and keeps trimming the power bill over time, while a generator covers the emergencies, the demand peaks, and the long grey spells when the panels can't keep up.
Run both, and you have almost every situation a farm throws up covered: low-cost power for the everyday, and dependable power for the days that would otherwise hurt. The farmers who get the most out of the EECA funding are the ones treating solar as a way to lower their long-run electricity costs, while keeping a well-matched generator on standby so a fortnight of foul weather never turns into a fortnight of lost production.
Solar is a sound long-term investment, but it isn't designed to provide complete energy independence for most dairy farms. If you want confidence that your whole operation will keep running whatever the weather does, take a look at AgriQuip's range of diesel generators, built to step in when solar and storage aren't enough.