Energy
Going Off-Grid in South Australia: When It Makes Sense (and When It Doesn't)
Going off-grid makes sense when connecting to the grid is expensive or impractical, which usually means rural and regional blocks a long way from the nearest line. For most homes that are already connected, it rarely stacks up financially. A grid-connected system with a battery usually gets you most of the independence for a lot less money and risk.
I've designed and sold off-grid systems across rural and regional South Australia and Queensland. The ones that work well all have one thing in common: they were designed for the worst week of winter, not an average day.
When off-grid is the right call
You're building on a block without power nearby. Before you decide anything, get a connection quote from SA Power Networks. On remote blocks, the cost of running a line in can be large enough that an off-grid system becomes the cheaper option, and you never pay a supply charge again.
You're replacing an unreliable or expensive connection. Some rural properties on long lines deal with regular outages. A well-designed off-grid system can be more reliable than the line it replaces.
You want full control and you're prepared to manage it. Off-grid means you're your own power company. That suits some people very well. It doesn't suit everyone.
When it usually doesn't make sense
If you're already connected in Adelaide or a regional town, disconnecting completely is rarely worth it. You'd give up feed-in credits, you'd need a much bigger system to get through winter, and you'd need a generator for the times it can't. For most connected homes, solar plus a battery on the right plan gets the bill close to zero while keeping the grid as your backup.
What actually determines the system size
Winter, not summer. An off-grid system has to cope with short days and runs of cloudy weather. Designers plan for "days of autonomy", meaning how many days the battery can carry the home without help. In my experience, two days of stored power is ample when there's a generator behind it, which lines up with the Australian standard for stand-alone systems (AS/NZS 4509).
The battery is the heart of it. On an off-grid system, the battery is what carries you through every night and every run of cloudy days. It's the most important part of the design, and the last place to cut corners.
Your real loads. Water pumps, heating, cooling, cooking, workshops: every one of them needs to be accounted for. Running heating or cooking on gas or wood can shrink an off-grid system considerably.
Plan for the generator
Power security is everything off-grid. There's no backup power line to fall back on, so a generator is strongly advisable. Modelling of Australian off-grid systems shows that even heavily oversized systems still need generator support at least once a year at some sites. Anyone who tells you a generator will never be needed isn't being straight with you.
An auto-start generator is less fuss because it kicks in on its own when the battery runs low, but it costs more. A manual-start generator is cheaper, but someone has to be there to start it. Either way, size it properly and budget for running it.
Rebates can still apply
Off-grid batteries can qualify for the federal battery discount, but only under conditions. The battery must be installed on a home that's lived in; sheds and bore pumps don't count. If the property is within 1 km of the grid, the battery generally needs to be VPP-capable, unless you can show that connecting would cost more than $30,000. The discount also tapers for larger batteries, so check the current rules with the Clean Energy Regulator before relying on it.
The mistakes I see most
Oversizing the solar on a closed-loop system. In a closed-loop system the battery and inverter talk to each other, and the battery decides how much charge it will accept. Adding panels beyond what the system can use doesn't buy you more power. It just means paying for panels that sit there curtailed.
Undersizing the battery. This is the big one. People trim the battery to bring the quote down, then find themselves running the generator through every cloudy stretch in winter. On an off-grid system, the battery is the last thing you should be saving money on.
The honest bottom line
Off-grid works brilliantly when it's the right fit and it's designed properly. It's an expensive mistake when it's sold to someone who'd have been better off staying connected, or when it's sized on a sunny-day estimate.
If you're weighing up off-grid for a rural property, or you've got a quote and want to know whether it'll actually get you through winter, that's exactly what a Clarity Session or Quote Review is for. Email jarrod@jarrodosborn.au anytime with a question before booking either one.
Weighing up off-grid? Get the design checked before you commit.