Charging Boat Batteries with Solar Panels | What Do I Need?

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In this article I’m going to give you a birds eye view what the installation process would look like if you want to install solar panels on your boat. Charging boat batteries with solar panels is a much easier process than one would think. Read till the end and leave any comments below if you have any questions.

Read our full in depth review on our best marine solar panels with buyers guide.

Lets get started

Before you can get started on buying solar panels you need to have a game plan first. What do you expected out of the panels you’re going to install?

  1. Keeping the start battery charged.
  2. Help to reduce engine/generator run time.
  3. Help produce enough power at anchor.
  4. Help produce enough power at anchor and passage.

All these options will require a different setup for obvious reasons.

How Many Solar Panels Do I Need?

Well before you can answer this you need to find out what your power usage will be. This seems scary and a difficult thing to figure out but it’s not.

Every item that you will be using regularly will have a power usage on it. Go around the boat and calculate what your power consumption would be. Some things won’t be running all the time like water pumps, fridge compressor, autopilot, bilge pump, etc… just do your best on calculating an average.

How Many Batteries do I need for my solar panels?

Now that you know your power usage you can calculate the batteries capacity you will need. If you calculate you will need roughly 100amps in a 24hour period then you would need a minimum of 200amp battery capacity. I would recommend going for triple if you can.

The reason for a minimum of double because most batteries can only be drained to 50% without causing harm to them

What is needed for Charging boat batteries with solar panels?

  1. Solar Panels and mounts
  2. Charge Controller
  3. Appropriate gauged wire
  4. Terminal connectors
  5. Heat shrink
  6. Inline fuse or breaker
  7. Inverter (optional)

Solar Panel Size and Mounting

When you look around a marina you can see all sorts of sailboats with many different solar mounting positions. The panel size you choose will have a lot to do with what space you have available. 

These are the most common mounting position to choose from.

Binimi 

The binimi mounting is ideal for a flexible solar panels. But care must be taken on if they will be sewn in or if they will be tied on.

Aft arch

If your sailboat has an aft arch or dingy davits then this is a very common area. This is my preference since you can keep them high up and out of the way. The wiring can easyily be placed in the stainless tubes or along side of them.

Railing mount

The benefits of the rail mounted panels is that they can be easily adjusted during the day to position the panels flat to the sun.

What is a charge controller and what does it do?

The charger controller regulates the power going into the batteries so they do not over charge. It also protects the solar panels from having power stream back from the batteries.

Do you need a charge controller?

In most cases you do. Although small panels that just trick charge a battery at a very low wattage do not require a charge controller.

What is the inline fuse for?

It’s there to protect the batteries from an overcharge if the charge controller malfunctions. Without one you can quickly find your self in a lot of trouble.

What is an inverter?

An inverter changes DC power into the common household AC power. You will need one if you have any household appliance on board.

Takeaway

I hope you have a good overview on how the system should look at a minimum. Take your time to research more about marine electrical systems before you just jump into the deep end.

If you have any questions feel free to reach out to us and will answer any questions you may have.

Happy Sailing!

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