Where Does a Sailboat Get Its Electricity?

Great question! Genuinely, it’s taken years for me to even begin to get my head around how electricity works on boats. So today, I’m hoping to be able to answer that question and have it make slightly more sense.

Shall we start with where our electricity comes from?

Batteries

Yep, batteries. You may not be that surprised — this is where pretty much all boats store their electricity, and it’s the same for us.

We have some pretty sweet batteries though: lithium.

Yep, you guessed it, they hold more charge for longer. This gives us way more flexibility when it comes to how much we can drain them, how fast we can charge them, and a few other cool things.

One of those ‘other cool things’ is how much smaller they are than the usual AGM batteries. We have 900Ah of battery capacity stowed away in a locker! I think that’s pretty impressive. If your keen to know more about them, go check out our episode on upgrading our power here.

Now, this is where our electricity comes from. Wires run from the batteries to things like computer chargers, water heaters, the watermaker (read more on that here), the electric kettle, etc, etc.

But, how do we charge them?

Well, thank you for asking! Let’s go have a look at the real places we get our electricity from.

#1 Solar

Solar is our favourite way to get electricity.

What is solar? If you’re not sure or don’t know, here’s my quickest and roughest answer:

Solar is when you capture the sun’s heat, rays, and power and turn it into electricity.

For us, we use solar panels. We have these mounted on a ‘solar arch’ off the stern, and also soft solar panels sitting on the roof. Put all of them together and we have quite a bit of power coming in on a sunny day!

To run our solar system, we also have to have MPPT charge controllers (don’t ask me any more about those, that’s Kris and Finn’s realm of expertise). These help tell us how much charge is coming in and also help manage how much is getting to our batteries.

When the sun is high and full force, it will charge our batteries right up to 100%. Those are great days, trust me! And they happen relatively often, actually.

But, solar kinda sucks on a cloudy day...

#2 Generator

Yes, we have a generator. It’s 9kVA for those who want to get technical. For those who aren't so technical — it’s a fair bit and plenty enough to help us keep the boat running on cloudy days!

Unlike solar, the generator doesn’t run off renewable energy, which is why we don’t like it quite as much. Burning diesel just isn’t an enjoyable experience, you know?

So yes, we have a battery charger that runs off the generator and pumps charge into the batteries. The generator can also run our inverter and watermaker, as well as everything 24-volt... the difference between 24V and 12V on a boat is a whole other post.

If we don’t get enough solar charge, you will hear the generator crank up for an hour or two to get the batteries back up to enough charge.

#3 Engine Alternators

On our drive engines, we have alternators that also produce power.

This is kind of cool because, even though we do our best to not run the engines (we’re a sailboat after all), we do have to, and so the fact that they put power into the batteries at the same time is a great help.

It definitely doesn’t charge as fast as the generator or solar does, but hey, take what we can get.

#4 Marina

Right, our least favourite and least-used method of getting electricity is plugging into a dock that uses power from the land power grid.

This doesn’t happen very often at all, and we’ll only plug in if we need to run the AC constantly or if we plan on leaving the boat.

But being plugged in keeps the batteries at 100% the whole time, and for some boats without solar, this is super helpful. You can head in and not have to run a generator or engine for a bit.

Often in marinas you pay for the power, just a note on that one.

How We Have to Be Very Electricity Conscious

On a boat, you have to be super conscious of any electricity you use. It’s crazy.

You have to be at a certain battery percentage before bed, and when you wake up and want to use the electric kettle for your morning coffee, you have to check you have enough power.

If not, you’re boiling the gas one.

You have to time when you run the watermaker and water heaters to try and make water off the solar energy.

It’s a challenge, and part of what makes boat life unique. I guess you can compare it to van life or tiny homes that are self-sufficient. It’s very similar, other than the fact that a lot of the time there is zero backup, and if the generator doesn’t start at night, you're suddenly in a spot of bother...

Summary

We get electricity by charging our batteries through solar power, our generator, and our engine alternators. Then we can draw from those batteries until they need charging again.

It’s an endless cycle that means we’re self-sufficient, but also very power conscious.

It’s different on each boat. They might have more or fewer batteries, or no solar, or a wind generator, but the principle of making and having your own electricity is the same.

I really hope this has helped answer the question of where our electricity comes from and maybe cleared up just one more part about boat life.

This is something you get used to. It can be annoying at times, but also rewarding when you find yourself making water off the sun’s energy and using renewable resources.

I’d love to know your thoughts on this topic and if you’ve ever used solar panels or had to boil your coffee because you didn’t have enough power!

Catch you in the comments.