Off-grid solar

Putting things right on an off-grid system in southern Tasmania

On a recent off-grid job in southern Tasmania, part of our design didn’t suit the way the property uses power. In this short video, George explains what went wrong, why it matters on sites that run freezers and other motor-driven appliances, and the equipment we’re installing to put it right for the owner.

George on site in southern Tasmania, with the Sigenergy system behind him and the replacement Victron gear ready to go.

Read the video transcript

Hi guys, it's George from REST Energy. This is probably, I suppose, not a great day for us, but behind us you'll see a Sig 10 kilowatt inverter with three batteries, gateway. It's off-grid, in southern Tassie. We made a bit of a blunder when we designed this off-grid system, I must admit. It is running freezers predominantly, which is an inductive load, so we thought the Sig'd be able to handle it, but it can't. It's giving us lots of problems and tripping out randomly. The next couple of days we're going to spend, we're going to rip the Sig out, and we're going to replace it with more traditional off-grid equipment which we do normally use. That's the Victron, Victron MultiPlus. She's all here ready to go. We've got two 16 kilowatt MPS Australian-made lithium batteries. And that's going to replace the Sig. We've all got it in front of us, it's not going to be too bad once we get into it. Anyway, onwards and upwards.

What happened on this job

This off-grid system in southern Tassie was built around a Sigenergy (Sig) 10 kW inverter with three batteries and a gateway, installed at the property’s shed. Freezers make up most of the load on the site, and when we designed the system we expected the Sig to handle them. On this property it hasn’t, and the system has been tripping out at random, which is a real problem on a site with no grid to fall back on.

As George says in the video, we made a blunder in the design, and we would rather be upfront about that. Our off-grid solar page says we stand behind our designs and that your system will perform to the specification we design it for. When one of our systems doesn’t do that, it’s our job to fix it, so over the next couple of days the team is taking the Sig out and installing the more traditional off-grid equipment we normally use.

Why freezers and other inductive loads matter off-grid

Freezers, fridges, water pumps and other appliances with an electric motor or compressor are known as inductive loads. When a motor starts, it draws a much bigger burst of current for a moment than it needs once it’s running. You’ll often hear this called startup surge or inrush current.

On a grid-connected home, the grid supplies those surges and nobody notices. On an off-grid property, the inverter and batteries have to supply every one of them, on top of whatever else is running at the time. Freezers add to the challenge because their compressors switch on and off many times through the day and night, so the system has to handle that surge over and over, including the times when two or more motors start close together.

If the inverter and battery setup isn’t matched to how those loads behave, you can end up with the kind of random tripping we’ve seen on this job. That’s why we look at the type of appliances a property runs as closely as the total amount of power it uses.

What we’re putting in instead and why

The replacement is a Victron MultiPlus inverter-charger with two MPS Australian-made lithium batteries, which George describes in the video as 16 kilowatt batteries. Victron Energy inverter-chargers and Australian-made Mictronix (MPS) lithium batteries are the proven off-grid equipment we list on our off-grid solar page, and it’s the setup George calls the “more traditional off-grid equipment, which we do normally use”.

Choosing this gear for a freezer-heavy site comes down to matching the equipment to the load. Sigenergy is still one of the battery brands we supply and install, and our Derwent Valley case study is a home running fully off the grid on Sigenergy battery storage. On this particular property, where freezers make up most of the load, we are going back to the Victron and MPS setup we normally use for off-grid work.

The new equipment is on site and ready to go, and as George put it at the end of the video, it’s onwards and upwards from here.

What this means if you’re planning an off-grid system in Tasmania

Every off-grid design should start with a full load assessment of everything you’ll run, and it helps to tell your installer about anything with a motor or compressor in it. When you’re planning a system, it’s worth talking through:

Appliances with motors: freezers, fridges, bore and water pumps, workshop tools and anything else that starts and stops on its own.
How often they cycle: how many times a day those appliances switch on, and whether several of them might start at once.
Winter use: how your power use changes through a Tasmanian winter, when there’s less sun to recharge the batteries.
Backup power: whether a backup generator makes sense for your property.
Future plans: anything you might add later, like another freezer, a workshop or a pump for a new water supply.

It also pays to choose an installer with off-grid experience who will stand behind the design if something isn’t working the way it should. You can read more about how we approach stand-alone power on our off-grid solar page, compare the solar batteries we install, or check the areas we service around Tasmania. If your property is already on the grid, our home solar page covers grid-connected and battery options.

Frequently asked questions

What is an inductive load?

An inductive load is an appliance that uses an electric motor or compressor, such as a freezer, fridge, water pump or power tool. These appliances draw a short burst of extra current when they start, and on an off-grid property the inverter and batteries have to supply it.

Can an off-grid solar system run freezers?

Yes, plenty of off-grid properties run freezers. The inverter and battery setup needs to be designed around how they start and cycle, which is why we begin every off-grid job with a full load assessment of everything the property will run.

Do you still install Sigenergy?

Yes. Sigenergy is one of the battery brands we supply and install, along with Sungrow, SolaX, FranklinWH, Tesla Powerwall and Australian-made Mictronix (MPS). We choose the equipment for each job based on the property and what it needs to run.

What should I do if my off-grid system keeps tripping out?

Start by talking to the installer who designed it, and give them as much detail as you can about what was running when it tripped. If you’d like to talk to us about an off-grid system in Tasmania, you can contact our team or call (03) 6170 1641.

Talk to us about off-grid power for your property

Tell us a little about your property and what you need to run, and we will give you a straight answer on what suits it.