A Complete Guide to Solar-Powered Electric Boat

The Solar Powered electric boat market is projected to reach $ 2.4 billion by 2031 from $ 0.65 billion in 2021.

And

There are 2 main factors that validate this growth projection.

1. Climate Change

The first is the climate change.

It has become a big concern for everyone.

And

burning fuel (diesel) is one of the main reasons behind this.

The excess carbon emissions are disturbing the ecosystem of the planet.

The consequences are many.

Let me list a few of them:

• Droughts
• Floods
• Melting of glaciers
• Migration of people, animals, and birds.

Many countries have imposed stringent emissions regulations to mitigate, control, and manage this change.

This has made people look for cleaner modes of water transport.

And solar-electric boats are one of them.

2. Fuel crisis

Another is the fuel crisis.

As mentioned above, conventional boats use diesel to sail on water.

This fuel is limited and will deplete in the future.

The fuel prices are rising and we will see erratic price movement in the future.

This uncertainty in prices and limited availability in the future bring anxiety to people using fuel engines for boats.

These 2 main factors will drive the growth of cleaner solar-powered electric boats as preferred water transport.

The working of Solar-Powered Electric Boat

The solar-powered electric boat takes energy from the sun.

A basic solar-powered electric boat has the following main components that make it run on solar energy:

• Solar Panels
• Charge controller
• Battery
• Inverter

It has mechanical aspects also such as hull design, dimensions, body shape, and others.

But I am discussing those important parts that make it different from conventional boats.

That is the source of energy.

a) Solar Panels

The solar panels are installed on the roof of the boat.

So that they can trap the maximum sunlight and convert it into electricity.

The solar panels produce a direct current which has a constant value.

This current goes into the battery through a solar charge controller and charges the battery.

b) Solar Charge Controller

You might be thinking of the role of a solar charge controller placed between the battery and the solar panels.

Although it is a small component but plays an important role in the system.

First, it regulates the charging of the battery.

This charges the battery in a more effective way.

And second, it prevents the backflow of the current from the battery to the solar panels.

Otherwise, it may drain the battery and damage the solar panels.

Hence, a solar charge controller improves the overall efficiency of the system.

c) Battery

From the solar charge controller, the current goes inside the battery.

Here it gets stored in the form of chemical energy (a kind of potential energy)

This energy can later be used when required such as at night or in cloudy weather conditions when the sunlight intensity is low.

d) SolarInverter

Many things in the boat such as the navigation system, its motor (although we have DC motors too), microwave, light, fans, etc run on alternating current.

But

Solar panels and batteries produce direct current.

Therefore, equipment is needed that takes in the direct current and produces alternating current.

The inverter does this function very effectively.

It takes direct current from the solar panels or the battery and produces alternating current.

And feed to the appliances and the propulsion system.

Hence, your solar-powered motorboat starts sailing in water.

The benefits of solar-powered electric boat

A solar-powered boat offers many benefits to its user.

Let me write a few important ones.

Environmentally Friendly

The process of absorbing the sunlight and producing current by the solar panel is completely environmentally friendly.

There are no carbon emissions in this process.

While on the other hand, conventional boats use diesel as a fuel. Which emits carbon in the air on burning.

Silent Working

Unlike diesel-powered boats which create loud noise from the generator, the operation of the solar-powered electric boat is silent.

A silently sailing motor does not disturb marine life.

Hence, you get more connected to marine life. This makes your sailing experience, if you are with your family, a memorable one.

Continuous Charging

The solar panels continuously produce electric power till the time sun is in the sky.

You can charge your boat and other appliances for free under this sunlight.

While on another hand conventional boats require frequent visits to the fuel stations to fill their tanks.

Reliable

The solar power system is reliable and durable.

They provide energy when there is sun in the sky.

Thereafter the battery is there to provide energy and run the boat at night.

Also, the solar panels are very durable.

They have a working life of over 25 years. It means that you are going to enjoy smooth sailing for decades.

Easy Maintenance

The complete solar power system in a boat is easy to maintain.

The solar panels installed on the boat require visual inspection and regular cleaning in terms of maintenance.

This reduces the overall cost of ownership.

Best Solar Panels for Electric Boats

By knowing the surroundings and the weather conditions in which a boat sails.

One can find the best solar panels for their boats.

The surrounding environment is wet, humid, salty, and corrosive

And the solar panels on the boat are always exposed to this environment.

The corrosion-resistant solar panels can withstand the eroding effect of salty weather.

In the sea, winds with high speed are a common phenomenon.

These high-speed winds create high pressure that can break down the solar panels.

Therefore, the right solar panel in this condition is the one that has a high wind load rating to withstand the wind pressure.

On a clear sunny day, when the sun is overhead.

The temperature rises.

This rise leads to an increase in the solar cell temperature too.

• Read: Best solar panels for hot climate

The solar cells are enclosed in the glass.

The glass effect traps the heat and increases the solar cell temperature even 15 to 20 degrees higher than the ambient temperature.

We all that with the rise in the cell temperature beyond 25 ᴼC, a solar panel starts losing its power (Pmax).

This power loss is a kind of monetary loss.

Therefore, a solar panel with a lower temperature coefficient of power is preferred.

So that the power loss can be minimized with temperature rise.

On a boat, managing its space effectively is always a priority.

The monocrystalline solar panels produce more power than the polycrystalline ones even in a limited space.

Also, the monocrystalline solar panels are sleeker in design and enhance the overall aesthetics of the boat.

Also, solar panels with long performance and product warranties are preferred.

How to size solar panels and batteries for your boat?

Solar panels of any size would not serve the purpose.

The under-sized may not produce that much energy and your energy needs are partially filled.

While an oversized system may cost you more and the energy remained unused.

Therefore, the right sizing of the system is desirable to maintain the balance between the energy produced and consumed.

The solar panels’ size depends on your energy needs.

If your energy consumption is high then you need more solar panels to meet the energy needs.

Sizing Solar Panels

Let us try to size solar panels for the following appliances and the equipment used in the boat.

We need a total of 10992 W-h of energy in a day to sail the boat.

And

when we take this energy from the sun it becomes a solar-powered boat.

Also, the sizing of solar panels depends on the peak sun hours in a region and the losses in the solar power system.

The Peak Sun Hours are the total sunlight intensity received per square meter area in a region on a particular day.

1 PSH = 1000 W/m²

PSH value of anything above 4 is considered good for solar PV technology.

Assuming an average daily peak sun hour of 5.3.

And considering 30% losses in the system.

You might be surprised to see the percentage of losses in the system.

Despite this, the solar power system offers an attractive return on investment.

There are many losses in the system such as:

• Shading losses
• Dirt losses
• Heat losses
• Age-related losses
• Energy conversion losses
• Transfer losses, and more.

These losses when add up can eat up 30% of the power produced by solar panels.

Therefore, we take a multiplier of 1.4 {1/(1-30%)} to oversize the ideal system by this value and compensate for the losses.

The formula for sizing the solar panels:
Solar Panel size (Watts) = 1.4 x (Energy needs/PSH)

Assuming a PSH of 5.3 per day

And

Energy needs as calculated above (10992 W-h).

We get, a solar panel size of 2900 watts or round it to 3000 watts

Or

3 kW Therefore, we need 3-kW solar panels to meet daily energy needs for sailing our solar-powered boat.

Battery Sizing

Solar Panels provide energy during the day.

For sailing your motor boat at night or in cloudy weather when the sunlight intensity is low.

You need a system that can propel your motorboat.

The batteries do this.

The chemical energy stored is used to power the propulsion system and run the appliances in the boat.

The right sizing of the battery helps the boat to sail smoothly.

The formula for the battery sizing is:
Battery Size (Ah) = {(Energy needs x days of backup)/(Battery voltage x DOD x Efficiency)}

• Energy needs = 10992 W-h
• Back up = 2 days.
• Depth of Discharge of 80%
• Conversion Efficiency of 90%

Putting all the values in the above formula, we get

In that case, the sizing of the battery would be:

Battery size (Ah) = (10992 x 2)/(12 x 80%x90%)

= 2544 Ah of capacity and the battery voltage is 12 volts

Or

If the battery voltage is 24 volts, then the capacity would be 1272 Ah (2544 Ah/2).

What should users look for before buying a solar-powered electric boat?

The buyer should focus on the following main aspects before selecting a boat:

The mechanical design of the boat

All boats are designed in a way that makes them sail smoothly and speedily on water.

We see a difference in the Hull design. The two-hull system parallel to each other is suitable for small and mid-sized boats.

Types of Solar Panels

We see two types of solar panels namely Monocrystalline and Polycrystalline.

Polycrystalline solar panels cost less when compared to those Monocrystalline ones of similar capacity.

However, the higher cost of Monocrystalline solar panels offers some advantages to its users.

• They are more efficient
• You get more power in a limited space
• Monocrystalline solar panels are more immune to heat-related losses.
• They are sleek in design, have a uniform color, and look more aesthetic on the boats.

Speed

The speed of the motor boats is defined in terms of knots 1 knot = 1.85 mph.

• Low speed = 4-8 knots
• Medium speed = 9-15 knots
• High speed > 15 knots

Battery Type

We see two main types of batteries Lithium-ion and Lead acid batteries.

Both store energy in chemical form and produce electricity when required.

The difference lies in their cost and performance.

Although Li-ion batteries are costlier than lead-acid batteries.

However, they provide certain benefits over the latter. Such as

• Lithium-ion battery more energy per unit of time.
• They are compact and occupy less space
• Less charging times
• Better depth of discharge
• High efficiency
• More useful cycles

Type of Motor

The motor is of 2 types, DC motor, and AC motor

AC motors are preferred over DC.

They are lightweight, compact, and high torque.

Price

The price of the solar-electric boat is one of the important factors that facilitate the buying decision.

The price of solar-powered electric boats starts from a few thousand dollars to millions.

It is up to the buyers what they want:

• A small boat with basic needs
• Solar-powered Ferry
• Big-size Luxury Yachts

Best Solar-Powered Electric Boats

The categorization of the best solar boats is done on their unique selling proposition.

1. GoSun Elcat Solar-Powered Electric Boat

Compact, light-weight and affordable solar-powered electric boat with a capacity of 6 persons in it.

Eclat Specifications

• Length: 14’9”
• Width: 8’2” and 6” in height
• Weight: 264 lbs
• Solar Panels of 200 watts with an MPPT solar charge controller
• Motor: 1.3 kW Brushless DC motor
• Battery: 1276 Wh Li-ion battery
• Top speed: 6 knots

This post contains affiliate link. It means I will get a commission upon successful buying. 
However, Eclat's affordability, compact design, and ease of assembling made me to recommend this solar-powered electric boat to you.

Features

• Compact and Portable
• You can charge via grid or solar
• Inflatable solar catamaran (having 2 hulls parallel to each other offers more stability to the boat)

Aditya: The solar-powered ferry by NavAlt Solar

India’s largest solar boat

It is the first commercially viable solar-powered water transport in India.

It has even won Gustave Trouve Award in 2020 for being the world’s best electric ferry.

• It has installed 20 kW solar panels on its roof.
• The 2 x 20 kW motors run it with a top speed of 7.5 knots.
• The 2-hulls (made of glass-reinforced plastic) parallel to each other give stability to the boat.
• This 20 m long and 7 m wide ferry can occupy 75 passengers in a single ride.

And it is the world’s first solar-powered ferry carrying approximately 1700 passengers per day.

It is very cost-effective and cheaper than similar boats that run on diesel.

The Kerala government is planning of replacing the entirety of its diesel fleet with solar ferries like Aditya.

Silent 60: Luxury Yacht

This solar powered electric yacht is suitable for long distance with all the amenities in it.

This Yacht is ideal for families who love adventure and luxury.

Features:

• Battery bank warranty: 8 years Cruiser: (143 kWh Li-ion battery)
• Solar panels: 25 years
• Electric motors: lifetime warranty
• CE-A certification
• Cruising speed: 6-8 knots and a top speed of 10-11 knots
• 4-6 cabins
• Very reliable and has almost zero maintenance

Conclusion

I foresee solar-powered electric boats will revolutionize water transport.

The carbon emissions regulations will refine further.

This will make people consider cleaner water transport modes.

And

Solar-powered electric boats are one of those great options.

Another trigger is rising and unstable fuel prices.

This uncertainty in fuel prices makes users look for reliable and affordable options.

And in solar boats, the source of energy is Sunlight which is available free to all.

Their easy and almost free maintenance is another advantage that reduces the overall ownership cost.

We will see more options in this category with time and advancement in technology.

The wide adoption and economies of scale with time will further reduce the cost.

FAQ (Frequently Asked Questions)

1. What is the range of solar-powered electric boats?

The range of any boat depends on many factors such as sunlight intensity, weather conditions, sailing speed, and the number of appliances used in the boat.

The sizing of solar panels is based on energy needs.

On a clear sunny day, the solar panels produce sufficient energy to propel the boat and run the appliances and gadgets in the boat.

Ideally, it has infinite range and you can sail anywhere.

However, at night or in cloudy weather conditions, the energy stored in the battery is used to power the boat.

However, in average weather conditions, the range can be extended by optimizing the speed and the use of the appliances.

2. Do solar boats sail at night or in cloudy weather?

Yes, solar boats sail in the night.

The energy stored in the battery provides power for propulsion and other appliances in the boat.

(The battery is charged in the day by the solar panels).

3. Top companies that make electric boats

• Navalt boats: Kochi, Kerala, India
• RAND Boats: Copenhagen, Denmark
• Aquawatt Green: Austria
• Boesch Motorboote AG: Switzerland
• Duffy Electric boat: USA
• Electra craft: California (USA)
• Torqueedo GmbH: Bavaria, Germany

4. Where is the market for solar boats?

All over the world.

• Europe (U.K., Germany, France, Italy, and other countries in the continent)
• North America (USA, Canada, Mexico)
• Asia Pacific (China, Japan, India, South Korea, and other countries)