What we look for when upgrading an off-grid system
A good off-grid upgrade starts with understanding what’s already on the property. Recently we visited a property in the Avon Valley where the owners wanted to add a new solar and battery system to a newly built shed. Before we design anything new, we walk through the existing setup to work out what can stay, what can be reused and what the new system needs to handle.
In the video below, we take you through that site visit step by step, from checking the existing inverter to measuring the surge load on the property’s bore pump.
Watch the Avon Valley site visit on YouTube
Step 1: Checking the existing Victron system
The property already runs a Victron MultiPlus-II 3 kW inverter/charger, fed by three strings of solar panels. Our first job was to confirm it’s healthy and doing what it should.
One of the big advantages of Victron gear is how easy it makes diagnosis. The notifications and settings screens show any faults straight away, so if something’s wrong we can usually pinpoint it quickly. In this case there were no notifications and no issues. The panels were producing well, the batteries were charging and discharging correctly, and the inverter was performing as it should.
That’s a good result for the owners. A healthy existing system means the new work can complement it rather than replace it.
Step 2: Planning the new shed install
The new system will go on a recently built shed. When we assess a roof, the first questions are how the panels will be mounted and where they’ll sit. This shed ticks the boxes: it’s solidly built, well insulated and has strong structural members up top, which makes for a secure panel installation.
Access matters too. The roof is relatively flat, so we can set up and tie off a ladder safely and install edge protection or use a harness and rope where required.
Inside, we look at where the inverter and battery will live. Solar and battery equipment derates in heat, so we keep it away from the warmer northern wall and use the cooler space available.
On equipment, we’re weighing up two options:
- Another Victron system, so it ties in with the existing setup the owners already know how to use
- A Sigenergy system, with one or two battery units depending on the final sizing
Step 3: Sizing the battery for winter, not summer
We size batteries on winter loads and winter production. Summer is easy: long days and strong sun mean plenty of yield. The real test is winter, when the days are shorter and the battery still needs to be full and ready when you need it.
That’s why we generally don’t install anything under 20 kWh of storage. It gives the household a few days of autonomy when grey, overcast weather settles in during the cooler months.
A lot of people judge a battery system on its summer performance and overlook winter. Designing for the hardest season is what makes an off-grid system reliable all year round.
Step 4: Allowing for the bore pump’s surge load
Bores are one of the most commonly underestimated loads on a rural property. The pump here is rated at 2.2 kW and 20 amps, and it’s a direct-on-line (DOL) start. DOL pumps can surge to around seven times their rated output at start-up, so this small bore needs roughly 14 to 15 kW available every time it switches on.
If that surge isn’t allowed for in the design, the system can trip off. That’s why we check every bore before we size an inverter.
The owners currently rely on a generator for the bore. That’s not ideal in summer, with fire bans in place and the risk of needing to start it during a fire. In our designs we integrate the bore into the system so owners can start their bore and reticulation remotely, without needing to be on site when a fire is coming through.
Why it pays to use electricians, not a sales company
Off Grid WA was started because we didn’t want to be another solar sales company. The solar and battery industry is full of businesses selling one-size-fits-all packages. We’re different: we’re electricians.
That means we look at the whole property, from the existing inverter to the bore out in the paddock, and design a system around how you actually live and work. We take pride in delivering off-grid systems that are reliable, so you can rely on us as your supplier for the long term.
Planning an off-grid upgrade or a new system for your property? Contact Off Grid WA to book a site assessment, and watch the full Avon Valley walkthrough on YouTube to see how we approach it.