Two years ago, we made the leap to full-time boat life aboard our 60ft x 10ft Dutch barge.
And with that came the challenge of designing an off-grid electrical system that could sustain us through all seasons, particularly the tough winter months.
We’ve already spent the best part of 3 years in our off-grid campervan that we drove around the world. And I designed and built the electrical system there myself.
So I wasn't a complete amateur going in. But the level of complexity on our boat was substantially more.
Not least because we had to work out what on earth the previous owner had done (most of it wrong) and then almost start again from scratch.
Below I want to take you through the rounds of changes we have made, to ultimately have a pretty epic off-grid boat electrical system. Complete with lithium ion batteries.
Let’s get into ….
We bought our barge in 2023, from an intermediary broker who had no real understanding of the boat and its past.
We have friends who live on boats and they came and took a look prior to buying. It seemed a pretty good deal, based on what was in there, though it was clear some things would need work.
As do all boats really!
I’ll be honest, we ended up needing to do a lot more to the electrical than I’d of liked. In the end spending roughly £6,000 on upgrading almost everything; and we did pay a professional company to do the work.
We didn’t HAVE to spend this much, but we wanted a really good spec of gear, both for peace of mind and also for making the boat more attractive to buy once we came to sell it.
Our Dutch barge has a large wheelhouse, which provides the perfect storage space for our battery bank. The batteries are installed below the boards beside the engine bay, keeping them secure and out of the way.
The batteries in there (4 x 115ah lead acids) ended up being pretty knackered.
We designed our electrical system to be as efficient and self-sufficient as possible, ensuring that all our appliances and devices have the power they need.
All our wiring runs through the bulkhead and sideboards, distributing power throughout the boat. We didn’t have to replace too much wiring in the ceilings themselves (though we did eventually replace all the ceiling lights from halogen to LED (trust me, this makes a HUGE difference).
Since we live aboard year-round, our power system needed to support:
The previous owner was hooked up constantly to the grid. So though he had batteries that needed charging and all 240v to go through his inverter; it didn’t matter what he ran.
For us, that all had to change.
Our power outputs ended up being much higher (as we work from the boat and wanted an air fryer) but we also needed more storage as recharging would be more sporadic.
We basically wanted all the mod-cons of living in a house, but in a house. As little compromise as possible.
In 2023 when we did our first round of massive updates, we installed lead carbon batteries. These got us through our first year and ended up being far better than straightforward lead acids.
They cost slightly more but can be abused a bit more, and do charge slightly faster. However by late 2024 we knew that we wanted to make the switch to lithium for our second winter on the boat.
Initially, we installed 8 x 115Ah lead carbon batteries. At the time, these seemed like the best balance between cost and performance. Lead carbon batteries were an improvement over standard lead-acid options because:
However, despite these advantages, we quickly encountered frustrations and limitations:
During our first winter, managing power was a constant worry.
We’d check battery voltage multiple times a day, trying to avoid dipping too low.
If we needed extra power in the evening, we often had to run the generator later at night, which wasn’t ideal.
After a year of dealing with voltage anxiety, we switched to 2 x 24V 300Ah lithium batteries from Roamer.
The improvements were immediate:
We had already used Roamer for almost 3 years in our camper. That's why we went for them.
In fact, talking to Roamer directly is what puts us at ease.
Very few boats (I don’t know any) even use lithium yet for their battery storage. Because in the past there have been a few damaging stories where people have installed dodgy lithium in their boats and there have been fires.
Nowadays, lithium is so much more stable, affordable and safe.
The 300ah battery in our van has been exposed to temperatures as low as -10 and as high as 40 degrees, driven halfway around the world.
So we know that Roamer makes great batteries and that the ones we put in our boat will never be exposed to the same levels of temperature variation.
Better still, the pricing between lithium and lead carbon really isn’t that big. Lithium can be:
On narrowboats in particular, I see lithium becoming the new norm very soon. They are limited to 2-4 leisure batteries simply because of space, nothing else.
With higher average electricity needs nowadays, I feel like more and more narrowboat owners will start making the switch simply because there's no other choice.
To learn more about our experience with these batteries read our in-depth Roamer batteries review here.
And you can check out Roamer batteries through their store here.
Okay let’s talk now about how we actually bring charge into our boat.
As we’re off-grid, we rely on solar as our main power source (at least in summer).
It’s worth noting that one other option to look at is wind, though where we are is relatively sheltered so a small turbine just hasn’t seemed worth it.
I’m fascinated by the idea of some sort of water turbine as well. But with the upfront costs and uncertainty, we just stick with solar as our one source of renewable energy on the boat.
We generate most of our power from five solar panels, connected to Victron MPPT controllers:
So how well do these perform for us? Well …
For about 4 and a half months of the year, we need a generator to supply our needs. We live on a beautiful spot with a castle and trees directly opposite. But in the winter this blocks the sun for most of the day.
And on the shortest day, the sun barely even comes out above the castle at all.
In the summer, it’s a completely different story. We don’t have to touch any other source of power for a full 6 months. In the summer, many days the batteries sit at float for hours.
It can be very frustrating, all that wasted energy in summer vs having to run a dirty petrol generator in the winter, but what can you do?
We have considered putting more panels on the boat, or updating the 2 older 150 watt panels. But even with those, we would still need to run a generator for 3 months of the year (or SIGNIFICANTLY cut back on power usage)
One of our boat neighbours uses no electric hookup all winter (he actually bought our 1.5 year old lead carbons off us when we switched to lithium and noticed a big improvement over lead acid).
But he works away from the boat all day and switches off his fridges and stores all food and drink in his wheelhouse because it’s so cold.
He only runs his TV when the solar has been good, and only runs his washing machine when it has been good as well. He even hooked his inlet for his washing machine to his hot water feed so the washing machine doesn't have to heat water when running.
All very smart, but for us, we simply can’t drop our electric use, so generator it is!
From mid-October to early March, we run a generator for roughly 2 hours per day (on average) to supplement solar.
When we upgraded to our new Victron system + lithium we worked closely with Roamer who remotely upped our generator to maximum capacity. When running, the generator puts in 60amps an hour for almost the entire charge cycle.
Which is impressive!
We were likely getting half that with our old lead carbons.
So though the generator runs a bit louder, we only have to have it on for maybe half the time.
Another perk to having lithium as you can just pump them full whack full of charge for almost the entire charge period; as opposed to lead acid/lead carbon whose intake of power massively drops off as they near absorption at about 80%.
Another perk of the lithium and the massive increase in overall capacity. Missing a few days of generator use isn’t a problem anymore.
It does mean that when we have to refill them if we miss a few days, then fully recharging from empty takes about 8-9 hours. But it’s nice to know we have that option and flexibility.
And my hope is that in early spring / late autumn where sunlight becomes more sporadic, we will have more leeway with the sun.
My thinking is, some days we have poor sun for 2 days straight but followed by one really big day.
With our lithiums, they can max out on the good days and have a lot more capacity to lose in those lower sun days. Meaning that we will hopefully be able to avoid the generator when times are like that (hopefully that makes sense!).
It’s one thing to have power stored in your batteries, but getting that power where it needs to go is just as important.
When we bought the boat, the original system had both 12V and 240V circuits, which is standard for liveaboard setups. But as we started replacing things, we had to make sure everything worked with the new system.
We didn’t design this from total scratch.
Most of the wiring and distribution setup was already there. But we did rip out the old inverter, batteries, and solar panels to put in a system that actually suited how we live.
Since boats have a mix of different appliances, we run three voltage levels:
24V appliances (run directly from the batteries):
12V appliances (powered via a 24V to 12V reducer):
240V appliances (powered by a 3000W Victron inverter):
The boat already had an inverter when we bought it, but it wasn’t powerful enough for what we needed. So we swapped it out for a 3000W Victron Multiplus, which has been perfect for running everything onboard.
It is still possible to trip of course, such as when running the toaster and kettle at the same time. But this is very rare and not exactly an inconvenience.
When we upgraded, we kept most of the original wiring in place. Everything runs:
Since boats are constantly moving, we’ve tried to avoid loose cables wherever possible. Everything is clipped down and routed through existing wiring channels.
One of the best things we installed was the Victron Cerbo GX. It lets us:
It’s connected to a 15-inch touchscreen, which makes checking our system super easy. The best part? It can also send email alerts, so if something goes wrong while we’re away from the boat, we’ll know instantly.
We will talk more on this below, but long and short is it’s not only convenient, but also necessary to meet boat safety standards for having lithium on a houseboat.
Having a solid electrical setup is great—but only if you know what’s going on with it. When we first moved onto the boat, we were guessing a lot. Were the batteries actually full? Were we using too much power? Was solar keeping up with demand?
Now, we don’t have to guess. Our Victron Cerbo GX system keeps track of everything and shows it on a 15-inch touchscreen display in our wheelhouse. It gives us a real-time view of exactly how much power we’re generating, using, and storing.
We also get to use the Victron Connect app (screenshot below). Which shows exact overall usage through the day. And allows us to keep an eye on battery levels when away from the boat for long periods (all it needs is a consistent WiFi connection).
We had already used Victron gear in our campervan, so we knew it was reliable. But the Cerbo GX takes it to another level. It connects to all the other Victron devices onboard—batteries, inverter, solar charge controllers, and more—so everything runs smoothly together.
One of the best things? It sends email alerts if anything goes wrong. So if we’re away from the boat, we can still check in remotely and see exactly what’s happening.
Switching to lithium was one of the best decisions we made—but it also came with extra safety steps. Unlike traditional lead-acid or AGM batteries, lithium batteries have different charging characteristics and require extra precautions, especially on boats.
When we installed our new system, we had to make sure it met both UK boating regulations and our insurer’s requirements. This wasn’t something we had to think about when upgrading our campervan, but on a boat, compliance is a big deal.
When we switched from lead carbon to lithium, we had to make sure our setup followed proper safety guidelines. Here’s what was required:
✔ Batteries must be securely mounted – Just like any boat battery, they need to be strapped down to prevent movement.
✔ Overheat and failure protection – A system must be in place to detect if the batteries are overheating or at risk of failure.
✔ Battery monitoring system – Real-time monitoring of battery voltage, charge status, and temperature is required.
We installed a Victron Cerbo GX to handle monitoring, which has worked perfectly for this. It allows us to keep track of battery health, charging status, and power usage in real time.
One thing we didn’t expect was how strict insurance companies can be when it comes to lithium. Before making the switch, we checked with our insurer (GJW) to see what was required.
Here’s what they needed:
Luckily, we already had a marine electrician who had installed the rest of our electrical system the year before, so he was able to install the lithium and issue the required certificate.
If you’re planning a lithium upgrade, we’d recommend checking with your insurer first to avoid any issues down the line. Roamer is also fantastic for this. They mapped out the entire system to meet regulations and just sent us all the gear in one package.
So not only do they make great batteries, they provide a one-stop convenient solution for upgrading to lithium on a boat. Better still, they are cheaper than most other lithium battery providers out there. It’s a win-win-win.
Going off-grid on a boat is a challenge, but once you get your system right, it’s completely worth it.
Over the past two years, we’ve upgraded and fine-tuned our electrical setup—replacing old batteries, installing more solar, adding a better generator, and setting up real-time monitoring. It wasn’t always smooth sailing (pun intended), but we’ve learned a lot along the way.
If you’re thinking about setting up your own off-grid power system, whether on a boat, campervan, or tiny home, here’s our biggest advice:
When we first moved aboard, we thought solar would be enough. And in summer, it is! But from October to March, it’s a different story.
If we had realized this earlier, we would have installed a bigger generator from the start.
Switching from lead carbon to lithium made everything easier. Faster charging, higher capacity, and no stress about damaging the batteries. If you’re still debating battery types, go with lithium—you won’t regret it.
We personally went with Roamer Batteries, which are designed for off-grid setups and fully comply with UK boating regulations.
You can read our full Roamer Batteries review here.
We didn’t realize how much easier a real-time monitoring system would make life until we installed the Victron Cerbo GX. Now, we can see exactly what’s happening with our power at any moment—no more guessing.
It’s one of the best things we added to our setup, and we’d highly recommend installing one early on. The Cerbo is fantastic as it also allows you to expand into other cool areas like level sensors for your water, waste and diesel levels.
Or even a way to divert leftover solar capacity to heat the water in your calorifiers for free!
Now over to you
Do you have any questions you think I missed?
Or any tips you have that we could use to upgrade our system?
I’d love to hear! So just drop a comment below …
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