A Guide To Marine Solar Panel Installations

Navigating the world of marine solar panel installations can be daunting. This article aims to simplify the process, providing a step-by-step guide to ensure your boat harnesses the sun’s power efficiently.

I understand the challenges of finding the right solar solution for marine environments, with so many factors to consider, from sizing to installation.

Drawing from extensive research and real-world applications, I’ve distilled the essentials, offering insights into the optimal utilization of solar energy on water.

For all boat enthusiasts and eco-conscious sailors out there, this guide is tailored to your unique needs and passion for sustainable marine adventures.

Just like you, I’ve faced the uncertainties of marine solar installations and, through trials and triumphs, gathered invaluable knowledge I’m eager to share with you.

🎯 Choosing Appropriate Solar Panels

Sizing the appropriate solar panels requires some thought and following the steps below.

Calculate The Electrical Consumption Of Each Device

A boat that uses an electric motor as its primary power source requires a much larger solar panel array (and the balance of the system) than one that doesn’t.

You must inventory every electricity device to calculate the boat’s electrical consumption. The value you are looking to calculate is the system watt requirement. 

If the wattage consumption is not listed on the device, you can calculate it by multiplying the current in amperes (A) by the voltage in volts (V)

Calculate The DAILY Consumption on The Boat

After listing each device’s consumption, you must work out its DAILY consumption. To do this, simply multiply the watts (from this previous step) and multiply this by the number of hours it will run each day.

It will result in a value called watt/hours.

When you have this value, add up each consumer’s “watt/hours” and arrive at a total daily consumption for the boat.

Calculate the Capacity and Number of Solar Panels

As a general rule, and in ideal circumstances, a solar panel’s daily production ranges between 2 to 5 times the advertised capacity (in watts). A 200-watt panel will generate between 400w-1000w (1 kW) daily.

Unfortunately, a boat is not an ideal environment, so optimal production will rarely be achieved.

We recommend sizing the panels with the assumption that they will only produce 1.5 to 2 times the rated capacity (this may vary according to the latitude the boat is sailing on and the sea conditions.)

Assuming the boat consumes 1,000 watts (1kw) per day, we recommend installing panels rated for 500 watts to 750 watts per hour.

Size and Space

Once you have calculated the required capacity, it’s time to go shopping. You can now find out which panels produce the required power and balance these against the space you have available.

As a general rule, the higher the solar panel’s production, the greater the efficiency in terms of space. Instead, buy a few high-production panels as opposed to many smaller units.

πŸ”© Installation Process

While installing a solar system is not difficult, it must be done extremely carefully. If you have not previously installed a solar system, we strongly recommend employing a professional to do the job.

Not only will the installation be done correctly (hopefully!), but you will also have recourse if there are any problems.

A few precautions should always be taken:

  1. If a solar panel is exposed to the sun, it produces electricity and should always be treated carefully.
  2. Always install the solar panels last and keep them covered when installing.
  3. Always use the correct gauge wire and the proper connectors – failing to do this may result in a fire.
  4. Always ensure that the correct size fuses are installed in the circuit.
  5. Label all wiring very clearly (this will be invaluable when you need to work on the system in a few years).
  6. Draw a full circuit diagram and any notes you may need to remind yourself why aspects of the installation were done in a certain way. Photograph this and store the image on your phone or computer – once again, in a few years, you will be thankful that you did.

πŸ”Ž Monitoring and Troubleshooting: System Monitoring 

Most charge controllers and inverters can provide in-depth statistics regarding the system’s electrical production and energy usage.

Most problems with solar systems are caused by incorrectly calculating the needed size of the system.

If you find a problem with the system, you should follow the steps below:

  1. Check the system statistics and look for the system’s daily production, yield, and consumption.
  2. If the consumption is higher than you predicted, you can take one of two actions (reduce the number of devices at any one time. The second option is upgrading the system to match the boat’s real-time consumption more accurately.

πŸŽ›οΈ Components of Marine Solar Panel Installation

The parts required for a Marine Solar Panel system are listed below.

Solar Panels

As listed below, three categories of solar panels can be used in a boat:

  • A Rigid Marine Solar Panel
  • A Semi-Rigid Marine Solar Panel
  • Flexible Marine Solar Panel

I’ve written a whole comparison of rigid vs flexible marine solar panels and their applications beyond the scope of this article.

1️⃣ Rigid solar panels are the most efficient in electrical production; however, being rigid means they can only be installed on flat surfaces or frames.

The frames that contain rigid solar panels are normally made from aluminum. Although they will flex slightly, they cannot be bent into shape.

Mounting rigid solar panels can challenge owners because there are generally not enough flat surfaces. To overcome this, many boat owners construct a stand-alone frame over the davits at the stern of the boat.

2️⃣ Semi-rigid panels are less efficient than rigid units. Their benefit is that they can be roughly bent to fit around corners. Flexible panels can be flexed against curved surfaces up to a radius of 30 degrees.

It makes them suitable for mounting on a Bimini shade or a curved deck surface. Some semi-rigid marine solar panels can be walked on, which makes them ideal for mounting on the deck fixed roof.

3️⃣ Fully flexible solar panels are the least efficient of all the types. Their advantage is that they can be molded to the mounting surface’s shape. Check out these market-leading flexible marine solar panels, which could be right up your street.

Charge Controller

There are several anomalies in the current produced by a solar panel:

  1. The solar panels generate a direct current (DC).
  2. The current fluctuates as the earth’s position relative to the sun changes during the day.
  3. On a boat, the current also fluctuates because the boat changes position relative to the sun.
  4. Cloud cover changes the sun’s effect on the panels.

All this means that it is essential to have a component that can manage the “volatility” of the solar panel’s current production and convert it into a usable power source.

The charge controller ensures that a maximum value charge is generated and does not exceed the limitations of the other components. To do this, they have a capability called Maximum Power Point Tracking (MPPT)

Charge controllers convert the solar panel’s production from DC-DC. It may seem strange, but they essentially convert the volatile DC from the panels into a controlled value required by the batteries.

It means they regulate the charge current into the battery and convert the voltage to match its needs.

A charge controller that is MPPT enabled will produce approximately 30% more current by the system.


The system will also need an inverter if the boat has any electrical consumers that require AC.

This component converts the DC power stored in the battery into a usable AC. 

The Charge Controller and Inverter are housed in many systems as a single unit.

Battery Bank

Batteries are needed to store the solar systems’ energy for later use when the sun is absent. Without an adequate battery system, no electricity would be available overnight or during cloudy overcast conditions.

They are a fundamental part of the solar system. Unfortunately, in terms of efficiency and sustainability, the batteries are the weakest component of the solar system architecture.

  • Batteries are heavy because most of the motor’s energy propels the battery!
  • Electric boats generally have a shorter range than the equivalent gas-powered boats.
  • Batteries cannot be recharged as fast as a gas tank can be filled.
  • Marine batteries have a finite lifespan, after which they must be replaced.
  • Generally speaking, batteries are the most expensive component of the solar system.

Here is a useful link if you want to dive deeper into the process of charging boat batteries with solar panels.


As a rule of thumb, the grade of wiring used from the solar panels to the charge controller should be as follows.

Amps produced by the Solar PanelsWire Grade
0 to 10A14 AWG wire
10 to 20A12 AWG wire
20 to 30A10 AWG wire
30 to 40A8 AWG wire
40 to 50A6 AWG wire


The correct specification connectors must be used for all connections between the solar panels and the charge controller.

The most commonly used connectors are

  • MC3
  • MC4
  • Helios H4
  • SolarLok
  • Radox

Your needs will determine the most suitable. Here is a brilliant article explaining the varying uses.

Mounting Hardware

The mounting hardware will be determined by the equipment being installed. Ensure you follow the manufacturer’s instructions and seal all holes with epoxy to ensure no moisture. 

πŸ‘ Benefits of Marine Solar Panel Installation

There are many benefits of solar-powered boats and installing a solar electricity-generating system on your boat. The quantifiable benefits that accrue will depend on the degree to which you convert to solar power. 

Reduced Fuel Consumption

The reduction in fuel consumption is directly proportional to the systems converted to solar energy. The options available include:

  • Replacing the battery motor’s alternator (or generator) with solar power 
  • Converting the main engine to electric power.

Replacing The Battery Motor’s Generator With Solar Power

Most boats have secondary systems (i.e., unrelated to the boat’s motor) that run off electricity. These tend to use lower-capacity batteries that are recharged when the boat’s gas-powered engine is running.

Examples of these systems include:

  • Lighting systems
  • Radios
  • Navigation equipment
  • The anchor cutlass
  • Electric sail trims
  • Refrigerators
  • Music and video systems

The systems generally consume less power than an electric boat motor. Because of this, a smaller solar system is required to provide power and recharge capability.

Converting The Main Engine To Electric Power

Purchasing inboard and outboard engines that run on electricity instead of fossil fuels (oil and gasoline) is now possible. 

Modern electrically powered motors are becoming more viable, and the efficiencies are continually improving. Electric motors are increasingly being seen as an alternative to gas-powered models.

The following summary lists the motors in the Torqeedo outboard motor range as an example of the range of electric outboards available. 

Torqeedo Outboard Motor Range

ModelHorsepowerRecommended Retail Price
Ultralight 403 A/AC1.0 HP$1,999.00
Ultralight 1103 AC3.0 HP$2,899.00
Travel 6032.0 HP$2,249.99
Travel 1103 C3.0 HP$2,949.99
Cruise 3.06.0 HP$4,298.00
Cruise 6.09.9 HP$4,298.00
Cruise 12.0 R Torq Link25.0 HP$4,898.00
Cruise 12.0 FP Torq Link25.0 HP$4,898.00
Deep Blue 2540.0 HP$10,599.00
Deep Blue 5080.0 HP$10,599.00

The following table lists the range of inboard electric motors available from Elco.

The Elco Inboard Motor Model Range

ModelHorsepowerRecommended Retail Price
EP-6 Electric Inboard6.0 HP$5,845.00
EP-12 Electric Inboard12HP$6,445.00
EP-20 Electric Inboard20HP$6,845.00
EP-40 Electric Inboard40HP$13,995.00
EP-70 Electric Inboard70HP$15,995.00
EP-100 Electric Inboard100HP$20,995.00
EP-200 ELECTRIC INBOARD200HP$59,995.00

The Advantages Of An Electric Motor

They offer the following benefits.

  • Lower fuel costs 
  • Less maintenance
  • Quieter running
  • More precise speed control

The Disadvantages Of An Electric Motor

While they are becoming increasingly efficient, current electric motor technology still has some drawbacks.

  • Electric motors are still more expensive, as per the following:
HorsepowerMercury OutboardTorqeedo Outboard
2.5 HP$945.00$2,899.00 (3HP)
9.9 HP$2,480$4,298.00
40.0 HP$6,060$10,599.00
80HP$9,275 (90HP)$10,599.00
  • Batteries offer less range and take longer to recharge.

Environmentally Friendly

There are obvious environmental benefits to switching to solar power:

  • Once installed and running, marine solar power installations are emission-free.
  • Solar power systems are virtually silent; they only generate noise from the inverter’s cooling fan.
  • When docked, a solar-powered boat has no electrical tethers connected to shore-based power supplies.

The Environmental Disadvantages of Solar Power

The disadvantages include the following:

  • Batteries that are most suited to solar installations (Lithium-ion) use metals that are environmentally costly to mine.
  • There are serious human rights violations in the mining of Lithium and cobalt.
  • Producing solar panels is an extremely environmentally expensive process with substantial emissions.
  • The end-of-life disposal of solar panels and batteries is a cause for concern.

Low Maintenance

One of the greatest advantages of solar power is the lack of maintenance that it needs.

Unlike gas-powered generators, there are no moving parts and, therefore, no wear from friction. Once a solar system is installed, it can be left alone, apart from ensuring that the solar panels remain clean.

Most systems allow warnings to be generated if out-of-limits situations occur (low battery, inadequate charge, etc.). In these instances, the user can inspect for the problem and take whatever action is needed.

There are only two circumstances where solar systems are vulnerable.

The Battery Is Discharged To Below The Depth Of Discharge Percentage

Batteries should be discharged within the depth of discharge limit the manufacturer sets. 

These limits are generally 50% (Lead acid batteries and related technologies) and 15% (Lithium-ion batteries).

If the batteries are discharged below these levels, the life expectancy will be reduced. It is normally catered for in the inverter, which will stop drawing current once these levels are reached.

Solar Systems Are Vulnerable To Lighting Damage

The main area of vulnerability is in respect of lightning. The massive electrical surge generated by a lightning strike can fry the solar panels, the wiring, the charge controller, the inverter, and the batteries.

Although the system should have substantial fuses built in, they generally cannot prevent damage caused by a direct hit.

❓ Frequently Asked

How often should marine solar panels be inspected and maintained?

Regular inspection and maintenance are crucial for the optimal performance of marine solar panels. It’s recommended to inspect the panels at least once a month for any dirt, debris, or damage. Clean the panels as needed to ensure they are free from obstructions that could reduce their efficiency. Additionally, check the wiring, connectors, and other components of the system for any signs of wear or damage and address any issues promptly.

Are there any safety precautions to consider when cleaning marine solar panels?

Yes, when cleaning marine solar panels, it’s essential to turn off the system and ensure that the panels are not producing electricity. Use soft cloths or sponges to avoid scratching the panels, and clean with mild soapy water. Avoid using abrasive materials or chemicals that could damage the panels. Ensure that the panels are dry before turning the system back on.

I’m the founder and chief editor here at Kite Ship. The electrification of boating is the most exciting thing to happen to the marine industry in a generation! Welcome, and I hope that we can provide the portal you need to dive into the world of electric propulsion and power.