Top 15 Questions About Marine Solar Panels

Solar panels are becoming increasingly popular among boat owners as a way to generate renewable energy and reduce their reliance on fossil fuels. However, with so many different types of marine solar panels available, it can be difficult to know where to start. This article answers the top 15 questions people ask when researching marine solar panels for their boats.

1. What are the different types of marine solar panels available?

Types of Solar Cells

There are three main types of solar cells used in marine solar panels: monocrystalline, polycrystalline, and thin-film.

• Monocrystalline solar panels are made from a single crystal of silicon, which makes them the most efficient type of solar panel. They are also the most expensive.  
• Polycrystalline solar panels are made from multiple silicon crystals, which makes them less efficient than monocrystalline panels but also less expensive.
• Thin-film solar panels are made from a thin layer of photovoltaic material deposited on a substrate, such as glass or plastic. They are the least efficient type of solar panel but also the most lightweight and flexible.

Panel Formats

It is important to note that monocrystalline and polycrystalline solar cells are available in both rigid and semi-flexible formats, providing options for different installation needs and preferences. In addition to the types of solar cells, marine solar panels are also available in a variety of formats, including:

• Flexible solar panels: These panels are made from a flexible material that can be conformed to the curved surfaces of a boat.
• Rigid solar panels: These panels are more durable and efficient than flexible panels, but they are also heavier and more difficult to install.
• Walkable marine solar panels: These panels are designed to be walked on, making them ideal for installation on decks and other high-traffic areas.

2. How much power can I expect from a marine solar panel?

The amount of power you can expect from a marine solar panel depends on a number of factors, including the size of the panel, the type of panel, the amount of sunlight it receives, and the efficiency of the panel.

A 100-watt solar panel can produce about 300 watt-hours (25 amp-hours) on average per day, with output being lower on cloudy days and higher on sunny days. However, this can vary depending on the factors mentioned above. For example, a high-efficiency panel may produce up to 4 times its nominal power in ideal conditions.

The location and seasonal changes can also significantly impact the power output of a solar panel. For instance, a 100W solar panel in Boston, Massachusetts, which averages 3.89 sun hours per day, can be expected to generate 389 watt-hours per day. In contrast, the same panel in Miami, Florida, with an average of 5.62 sun hours per day, can generate 562 watt-hours per day . This highlights the importance of considering location and seasonal variations when calculating solar panel array requirements.

One way to combat the decreased direct sunlight in higher latitudes and during winter months is by adjusting the angle of your solar panels. By tilting the panels towards the sun, you can maximize the amount of sunlight they receive and improve their overall efficiency.

3. How do I choose the right size solar panel for my boat?

Choosing the right size solar panel for your boat requires careful consideration of your energy needs and several other factors. This includes the amount of power you use each day, the number of days you want to be able to go without recharging your batteries, the capacity of your batteries, and other charging sources available on your boat.

Here's a step-by-step guide to help you determine the appropriate solar panel size:

1. Estimate Daily Energy Consumption: Make a list of all the electrical devices you use on your boat, their wattage, and the number of hours you use them each day.
2. Calculate Battery Bank Capacity: As a general rule of thumb, your house battery capacity should be 3-4 times bigger than your daily energy consumption. In the example above, with a daily consumption of 952 Wh, you would need a battery bank with a capacity of roughly 2856 - 3808 Wh.
3. Consider Charging Sources: Take into account other charging sources you have on your boat, such as your engine, wind generator, or shore power . These sources can supplement your solar panels and reduce the size of the solar array you need.
4. Factor in Battery Capacity: Remember that you cannot draw below 50% charge on your batteries without shortening their life, and you will seldom charge past 85% while away from the dock. As a result, only 35% of the nameplate capacity is really usable.
5. Estimate Solar Panel Output: For solar panels, take the rated wattage x 5 hours/12 = amp-hours while on passage and wattage x 7 hours/12 = amp-hours while at anchor (sails do not shade and the boom can be rigged out to the side). This is a general starting point, and actual output will vary depending on factors like location, weather, and shading.

By carefully considering these factors, you can determine the appropriate size solar panel for your boat and ensure you have a reliable and efficient power source for your onboard needs.

4. What is the best way to install solar panels on a boat?

The best way to install solar panels on a boat depends on the type of panel, the available space on your boat, and your specific needs.

• Rigid solar panels are typically mounted on a hard surface, such as the deck or cabin top. They are often installed using mounting rails or brackets that are secured to the boat's surface.
• Flexible solar panels can be mounted on curved surfaces, such as the bimini or dodger. They can be attached using adhesives, zippers, or Velcro.

When installing solar panels, it is important to:

• Choose the right location: Select a location that receives maximum sunlight and is not shaded by sails, rigging, or other equipment. For example, dinghy davits are a popular location for solar panels as they are often unshaded and can be easily accessed.
• Use marine-grade wiring and connectors: Marine-grade wiring and connectors are designed to withstand the harsh marine environment and ensure a safe and reliable installation.
• Mount the panels securely: Secure mounting is crucial to prevent damage to the panels, especially for flexible panels that are more susceptible to cell cracking and intercell connection failure if they are not properly supported.

5. How do I maintain marine solar panels?

Regular maintenance is essential to ensure your marine solar panels continue to operate efficiently and have a long lifespan. Here are some key maintenance tasks:

• Cleaning: Regularly clean the panels with fresh water to remove dirt, salt residue, bird droppings, and other debris that can accumulate and reduce their efficiency. You can use a soft cloth, mild soap, and freshwater for cleaning, but avoid harsh chemicals or abrasive cleaners that can damage the panels.
• Checking connections: Periodically inspect the wiring and connections to ensure they are tight and secure. Loose connections can cause resistance and reduce the amount of power generated by the panels.
• Inspecting for damage: Regularly inspect the panels for any signs of wear and tear, such as cracks, scratches, or discoloration. Early detection of damage can help prevent further problems and ensure the longevity of your panels.

6. What are the benefits of using marine solar panels?

Marine solar panels offer numerous benefits for boat owners, making them an increasingly popular choice for onboard power generation:

• Renewable energy: Solar panels generate clean, renewable energy, reducing your reliance on fossil fuels and minimizing your environmental impact.
• Cost savings: By generating your own electricity, you can reduce or eliminate fuel costs associated with running a generator or engine to charge your batteries.
• Environmental friendliness: Solar panels are a sustainable and environmentally friendly way to power your boat, reducing emissions and promoting cleaner boating practices.
• Quiet operation: Unlike noisy gas-powered generators, solar panels operate silently, providing a peaceful and enjoyable boating experience.
• Increased battery life: Solar panels can help extend the life of your batteries by providing a constant trickle charge, especially during the "float" cycle, which can take a long time with other charging methods.
• Emergency power: In case of a mechanical breakdown or other issues with your primary power source, solar panels can provide a reliable backup power source for essential equipment, such as VHF radio and navigation lights.

7. What are the drawbacks of using marine solar panels?

While marine solar panels offer significant advantages, there are also some potential drawbacks to consider:

• Dependence on sunlight: Solar panels rely on sunlight to generate electricity, so their output can be limited in cloudy conditions or at night.
• Space requirements: Depending on your energy needs, solar panels can take up a significant amount of space on your boat, which may be a concern for smaller vessels.
• Initial cost: The initial cost of purchasing and installing marine solar panels can be relatively high, although this can be offset by long-term cost savings on fuel.
• Potential for damage: Solar panels can be vulnerable to damage from hail, storms, or impacts from objects, especially rigid panels with glass coverings.
• Shading: The efficiency of solar panels can be significantly reduced if they are shaded by sails, rigging, mast, boom, or other objects on the boat . Careful planning and installation are essential to minimize shading.
• Charge controller conflicts: If your boat has multiple charging sources, such as solar panels and a wind turbine, it's crucial to ensure the charge controllers for each source are not set to the same maximum voltage set point. This can lead to conflicts and potentially damage your batteries. Ideally they are networked together and operate knowing the other exists. Easy to do with Victron components, let us know we can send you the video link, it is simple and quick.

8. How much do marine solar panels cost?

The cost of marine solar panels can vary significantly depending on several factors, including the size, type, brand, and efficiency of the panel.

• Flexible solar panels: Typically cost between $200 and $800, depending on their wattage and features.
• Rigid solar panels: Can range from $500 to $1,500 or more, depending on their size, wattage, and cell type.

You can also purchase complete solar panel kits that include everything you need to install a solar panel system on your boat, such as the panels, charge controller, wiring, and mounting hardware. These kits typically cost between $600 and $3,000, depending on the components included and the overall system size.

9. Do I need a charge controller?

Yes, most marine solar panel systems require charge controllers. Charge controllers are essential components that regulate the voltage from the solar panels to prevent overcharging and damaging your batteries. They ensure that the batteries receive the correct amount of voltage and current to maintain their health and prolong their lifespan.

In addition to charge controllers, you may also need an inverter, depending on your boat's electrical setup and the appliances you need to power. Inverters convert direct current (DC) electricity from solar panels and batteries into alternating current (AC) electricity, which is used by many common household appliances, such as TVs, microwaves, and laptops. If you plan to use such appliances on your boat, an inverter will be necessary.

When installing a system with multiple charging sources, such as solar panels and a wind turbine, it's crucial to avoid charge controller conflicts. This means ensuring that the charge controllers for each source are not internally adjusted to the same maximum charge voltage set point. If both controllers are set to the same voltage, they may interfere with each other, leading to inefficient charging or potential damage to the batteries. With Victron components they are easy to network together so they work most efficiently.

10. What are the best brands of marine solar panels?

When choosing marine solar panels, it's essential to select a reputable brand that offers high-quality, durable, and efficient panels. Some of the leading brands in the marine solar panel market include:

• SunPower: SunPower panels are known for their high efficiency, durability, and long lifespan. They are a popular choice for boat owners who want to maximize power output in a limited space. However they are no longer in the marine solar business. All Sunpower marine panels are old stock.
• Custom Marine Products: CMP specializes in most available types and sizes of  marine solar panels, including bimini mount, pole mount, rail mount, deck mount, arch/davit mount.  Flexible, rigid, and walkable panels. They use the highest efficiency commercially available A+ grade 24.4% efficient solar cells from Sunpower (and other high end solar cells). They also make their panels shade tolerant, separating each panel into at least four distinct sections that operate independently.
• Solbian: Solbian specializes in flexible and semi-flexible solar panels that are lightweight, durable, and designed to conform to curved surfaces. They are a good option for boats with limited space or those that require flexible mounting options.
• Solara: Solara offers a range of marine solar panels that are known for their durability and ability to withstand harsh marine conditions. They are a reliable choice for boat owners who prioritize long-lasting performance in demanding environments.
• Solarland: Solarland provides quality-built, rugged solar panels that meet industry standards and are suitable for various off-grid applications, including boats. They offer a balance of performance and affordability.

11. How long do marine solar panels last?

The lifespan of marine solar panels can vary depending on several factors, including the quality of the panels, the installation, and the environment in which they are used.

In general, marine solar panels can last for 5-25 years. It is important to note that the output of solar panels will gradually decline over time due to factors like cell degradation and environmental exposure.

To maximize the lifespan of your marine solar panels, it is crucial to:

• Choose high-quality panels: Opt for panels from reputable brands that use durable materials and construction methods.
• Ensure proper installation: Securely mount the panels to prevent damage from vibration, flexing, and environmental factors.
• Perform regular maintenance: Keep the panels clean and free from debris to ensure optimal performance.
• Protect from damage: Take steps to protect the panels from potential damage, such as hail, storms, or impacts from objects.

It's important to highlight that while home solar panels have standardized reliability standards, marine solar panels do not have the same level of standardization. This means boat owners need to be more careful when choosing marine solar panels and should prioritize reputable brands with good warranties to ensure long-term performance and reliability.

12. What is the average daily output of marine solar panels?

The average daily output of marine solar panels can vary significantly depending on factors such as location, weather conditions, panel efficiency, orientation of the panels to the sun, and shading. However, as a general rule of thumb, solar panels can be expected to produce 3 times their nominal power each day. For example, a 100-watt panel would produce an average of 300 watt-hours (25 amp-hours) per day. High-efficiency panels can produce even more, potentially up to 5 and 6 times their nominal power. They can produce even more at different latitudes, the farther north you go in the summer, for example, the more sunshine is available each day for power production.

13. How does shading affect marine solar panels?

Shading can significantly reduce the efficiency of marine solar panels. Even partial shading of a single cell can affect the output of the entire panel. This is because solar panels are connected in series, and if one cell is shaded, it can limit the current flow for the entire panel. Therefore, it's crucial to choose a location for your solar panels that receives maximum sunlight and is not shaded by sails, rigging, or other equipment.

That said, Custom Marine Products is one manufacturer that mitigates the effects of shading in several ways, including wiring the panels so they are in two halves at a minimum, and then separating each string of cells by diodes so the panels are in quadrants at a minimum. They also use the Sunpower A+ grade cells that are themselves shade tolerant, where any portion of the cell can be shaded and the rest of the cell continues to produce power.  This is very different from most solar cells where if a portion is shaded the entire cell and thus the entire panel loses significant power.

14. What are the different types of charge controllers for marine solar panels?

There are two main types of charge controllers for marine solar panels: Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT). PWM controllers are simpler and less expensive, but they are also less efficient than MPPT controllers. MPPT controllers are more complex and expensive, but they can extract more power from the solar panels, especially in low-light conditions or when the panels are not optimally angled toward the sun. MPPT is what you want on a boat.

15. Can I install marine solar panels myself?

Yes, many boat owners choose to install marine solar panels themselves as a DIY project . However, it's essential to have a good understanding of electrical systems and to follow proper installation procedures to ensure a safe and reliable system. If you are not comfortable with electrical work, it's always best to consult a qualified marine electrician for assistance.

Conclusion

Marine solar panels are an excellent way to generate renewable energy on your boat, offering a range of benefits, including energy cost savings, environmental friendliness, and increased battery life . When choosing marine solar panels, it's essential to consider factors such as your energy needs, the type of panel, installation requirements, mounting styles, and maintenance needs. By carefully evaluating these aspects and selecting high-quality panels from reputable brands, you can enjoy the many advantages of solar power for a more sustainable and enjoyable boating experience. Shop all the best Marine Solar Options at Custom Marine Products.