It started with our family needing a bit more space at home. We have enough elbow room for all the day-to-day life things, but we were all missing some creative space. And our teens could definitely do with a separate social space.
After exploring the possibility of moving house and calculating the long-term cost of getting a bigger mortgage, we eventually decided to upgrade where we are.
Also, facing the idea of leaving our garden, which we have cultivated for 17 years, is no small thing — as any gardener would know. It’s a living thing that you’ve come to know. When we first moved in, there was just grass and a sickly quince in the backyard. We now have a lush urban orchard full of food, flowers, and natives that would be hard to replace in a hurry.
All things considered, we decided that the most sensible option would be to build a sleepout in the backyard.
We hired a friendly local builder to construct a simple 19m² structure with no plumbing or sewerage. We just need electricity for lights, a bit of heating, and whatever projects or entertainment we need there.
We have an outside laundry about 10-15 metres from the build, so we assumed that we could dig a trench and connect the sleepout to the little fuse board in the laundry building. Easy small job.
We felt sure enough about this that we didn’t really factor it heavily into our budget. It was sort of a peripheral thing that wouldn’t be a big deal. Just hook it up and switch it on.
Well, unfortunately, that wasn’t the case.
It turns out there was not enough power going to our laundry to run another building off it, so the connection would need to go all the way back to our main switchboard.
That meant:
What we had thought would be a $2-3k electrical job was suddenly pushing $9-10k for wiring the sleepout and connecting it to the mains.
And, with an old house, you never know what you are going to find when you start messing around with things. We know from experience that the estimated budget for any project can quickly escalate. Scary. Granted, we are perhaps also a bit out of touch with inflation. It’s our first major renovation in seven years or so, but still, it made us really reassess our plans.
Now that we had some actual costs in front of us, we started thinking seriously about solar.
The bones of the sleepout.
It looked like we could get a modest solar kit with batteries for about the same cost, or less, than it would cost to connect the new building to the mains.
The connection part of the electrical quote alone was about $4k, and then we would also have to pay for the power ongoing. And power prices keep going up, so in theory, the idea of solar made a lot of sense. An equivalent upfront investment and then free power ongoing? Sounds good. Take my money!
But getting advice on solar has not been that easy.
There are suppliers of solar hardware, and then there are people who can install it. It was actually a bit difficult to firstly get clear advice from an electrician who knows solar, but also to get them to understand our actual power needs for the building. Our power needs are modest, and we can accept running out of power sometimes.
The advice we got was largely targeted at peak-use scenarios:
We are pretty sure we don’t.
And I get it, a professional wants to do best practice, so no one has reason to later complain.
But what if not over-investing is a key consideration?
We are taking on more mortgage for this project, and we know exactly how long it will take us to pay it off.
As soon as we started looking at solar kits and installations, we re-encountered the issue of unknown escalating costs.
Not only is it a lengthy process to get multiple quotes from someone who also fully understands our requirements, but as mentioned, there will always be unforeseen circumstances in any construction project.
So once again, we were faced with the possibility of a ballooning budget blowout.
It would be nice if there were a version of this that we could safely control ourselves without needing an electrician at every step. For example, if we started with a modest solar setup that turned out not to be enough, we would be reliant on an electrician to scale it up — again at an unknown cost.
What we were really looking for was a solution with a predictable cost that we could control. Eventually we came across portable power stations. A portable power station is essentially a very large battery bank with a built-in inverter that manages the comings and goings of different voltages. They have charging inputs for solar panels or an extension cord from a mains socket, and can output normal household electricity, so we can use normal appliances.
At this point in the plan, we divided the electrical project into two parts:
The interface between the two will be a caravan plug on the outside of the building, where we can plug in our power station, or an extension cord if we ever get desperate.
It's slowly coming together!
At the moment, we can get a plug-and-play solar system for between $3-4k, depending on the brand, with 3kWh of battery storage. In theory, a couple of solar panels should be able to charge that each day if it is not too cloudy.
We have a fairly rudimentary understanding of what 3kWh of electricity actually means. For example, we know that our whole household uses an average of 13kWh per day, so 3kWh sounds kind of reasonable for one room that we don’t use every day.
However, we do want to keep it warm so that it stays healthy and mould-free. With 3kWh, we could run a small 500W heater for around six hours, or run the heater for a couple of hours along with the lights and a 100W sewing machine, which would do.
As you can probably tell, there are still quite a few “ifs” and “depending ons” in this plan. But as I said earlier, we are up for it.
If it is not enough, we can plug in expansion batteries and add more solar panels. Some brands support this, some don’t. Make sure you also understand your power station’s maximum solar input so you know how many panels you can actually add in the future.
At this stage, this is still all hypothetical.
I’ll be sure to follow up with a proper reality check once we have the wisdom of hindsight and can say whether any of this actually worked the way we imagined.
This is the first article in a two-part series about building our backyard sleepout and experimenting with an off-grid-style solar setup. The second article will cover how the system actually performed once everything was installed and in daily use.
