Over the last decade, massive improvements have been made with solar power technology, making it more efficient and affordable to use solar panels on an individual level. The sailing community uniquely benefits from the improvements, as a single solar panel can charge boat batteries, and multiple panels can fully power onboard appliances. While it’s not tough to decide to install marine solar panels on your boat, navigating through a new and complex topic can be challenging. This guide helps simplify the process of buying marine solar panels, allowing you to harness solar power sooner without wading through loads of detailed information.
What are the Benefits of Installing Marine Solar Panels on Your Boat?
There are numerous benefits of adding solar power to your boat, and those benefits are only growing as solar technology and innovation are furthered. Among the most alluring of these benefits is the money you’ll be able to save by generating renewable energy. Of course, there will be the upfront costs of purchasing and installing the system, but those are one-time costs that free electricity will make up for over time. Between the fluctuating fuel prices and operating costs of generators, who wouldn’t be happy to switch to a more consistent alternative?
Another great benefit of using solar to power your boat’s electricity is that you don’t need to monitor the system as it produces energy. This makes it possible to leave your boat, take a nap, or simply enjoy leisure time while your batteries recharge.
An often overlooked benefit is that solar panels operate silently, so you won’t have to worry about bothering neighbors or marine life while in use. This can be particularly beneficial when you’re snorkeling or diving from your boat. Loud generators scare away marine life, making your time in the water less enjoyable than it would be if you were using a solar energy system.
How do Marine Solar Panels Work?
Solar panels for boats work just about the same as any other portable solar energy production system. There are four main components to solar energy systems. Suppliers sell the components individually, or as pre-arranged solar panel kits:
- Solar Panels
- Charge Controllers
The system generates electricity through the solar panels and the inverter. When sunlight hits the solar panels, it creates an electrical current that runs to the battery via the charge controller. The charge controller regulates the amount of energy (voltage) that a battery receives, as too much voltage can overload and damage the battery. The amount of electricity that the system produces depends on the size of the panels and the amount of sunlight they receive.
Whether or not you’ll need an inverter as part of your solar power system depends on your boat’s electrical setup and the type of current your boat’s electronics and appliances use. An inverter converts Direct Current (DC) electricity into Alternating Current (AC) electricity, so you won’t need an inverter if you only run DC electronics and appliances. Refrigerators, dishwashers, toasters, and microwaves are all examples of items that run on AC electricity, so you will likely need an inverter if you spend a significant amount of time on your boat.
Types of Marine Solar Panels
Depending on your energy requirements, your budget, and your installation location, one type of solar panel may work better than others. There are three different types of marine solar panels worth considering for your boat:
Each has its own advantages, so you should understand the differences in solar cells to efficiently outfit your vessel. As a quick note, all solar panels discussed here are sensitive to shading. Once partial shading occurs, it drastically reduces the amount of energy the solar panel can produce. If multiple cells are shaded, the solar panel is almost entirely unable to produce energy.
Monocrystalline Vs. Polycrystalline Solar Panels
While each type of solar panel shares common electricity production features, there are a few key differences to consider before installing one type over the other on your boat. The main difference to be aware of is the type of solar cell each panel uses.
Monocrystalline solar panels use solar cells made from just one silicone crystal, while polycrystalline cells are made up of many silicone crystals melted together. The difference, simply put, is that monocrystalline cells take up less space without losing efficiency. We’ll keep our explanation simple. However, you may be interested in learning more about how silicon solar cells are formed and applied to solar panels before making a purchase.
Both monocrystalline and polycrystalline solar panels are rigid fixtures, so you’ll need to have a suitable area on the boat to install them.
Most consider monocrystalline solar panels to be superior to polycrystalline and amorphous solar panels in terms of efficiency and looks. The single crystal solar cells are made from high-quality silicone and arranged neatly to maximize space efficiency. They also form a relatively attractive pattern for those concerned with aesthetics. Monocrystalline solar panels are the most heat tolerant, remaining relatively efficient in even the harshest conditions. They are also (generally speaking) the longest-lasting panels of the group. As expected, though, they are the most expensive option.
Polycrystalline panels aren’t as efficient as monocrystalline panels, so they require more surface area to generate the same amount of energy. As a tradeoff, these panels are less expensive and are slightly less sensitive to shading.
Amorphous Solar Panels
Amorphous solar panels are only about 50% as efficient as crystalline panels, but they come with a huge benefit. These silicone solar panels are flexible. You can roll, fold, or wrap surfaces that are otherwise unable to house a rigid solar board. The ability to conform to odd shapes makes them perfect for use on various boat surfaces. They also differ in the way of their ability to generate electricity. Amorphous panels are especially susceptible to heat, and their production drops off entirely when they get too hot. They are far more efficient than crystalline panels in low-light conditions, though, so they’re ideal in overcast conditions. Due to their low electricity generation, most people only use these panels for trickle-charging their batteries.
Calculating your Boat’s Power Consumption
Calculating your power needs can be tricky, especially if you’re just getting set up on a new boat. Each boat requires different amounts of energy, and each person or crew will use different types of electronics and appliances. You also need to consider how many hours of sun your boat sees, which is an educated guess at best. With that said, some boats can get by on a single 100-watt solar panel. Others need multiple panels just to run the appliances.
While there really isn’t an “easy” way to calculate your boat’s electrical energy demand, there’s a relatively simple formula to follow to estimate your solar generation needs. First, you’ll need to take inventory of your electrical appliances and find their current ratings. Then you can calculate their average power consumption in Watt-hours. The easiest way to compile the information is to input it into an excel spreadsheet. Once you calculate the Watt-hours, you can determine how many solar panels you need to run your boat on solar energy. Keep in mind that the efficiency of most solar panels is around 15%, so you’ll need to calculate appropriately.
Where Should You Install Solar Panels on Your Boat?
Once you decide on buying solar panels for your boat, you’ll need to choose where to install them. Choose an area that the panels will be free from any potential collisions with winches or sails. You should also install them perpendicular to the sun and free from any shading that occurs throughout the day. Expose the panels to a fair amount of wind to assist with cooling. Efficiency increases as the panels’ temperature decreases. It’s common to install marine solar panels on top of dinghy davits. Davits at the back of the boat offer good exposure and few other things around the structure. Flexible or semi-flexible solar panels can canvas various shapes and surfaces, so you’ll have more mounting options available.
Other standard mounting options include:
- Fixed Mount
- Adjustable Mount
- Top-of-Pole Mount
- Bimini Mount
- Deck Mount
- Side Mount
What Supporting Equipment Do I Need for My Solar Panels?
As stated in previous sections, there are multiple components to solar generation systems that you must keep in mind. Not only will you need to carefully place your panels, battery, and inverter, but you’ll need to match the battery and supporting equipment so that all things remain compatible. On most days, your solar generation will only happen over a few hours every day, so you need to have an appropriately sized battery to store the power you need. We suggest having a large enough battery to run your boat’s electronics and appliances for a minimum of 24 hours, and preferably two or three days when possible. Having too big of a battery will suffer from undercharging issues, and having too small of a battery won’t be able to keep up with your boat’s energy demands.
You can determine the battery size you need just as you calculated your total energy needs – by calculating Amp-hours. You don’t want to run your battery below 50% capacity, as it can damage the functionality and efficiency. So, if your battery bank has a total of 500 Amp-hours, you have 250 Amp-hours of usable energy. That 250 Amp-hours can run 10 amps of power for 25 hours in total.
Solar Charge Controller
After arranging a balance between the power output of your solar panels and the intake from your battery, you’ll need to choose an appropriate charge controller for your system. But first, what exactly does a charge controller do? Solar panels and batteries produce and accept energy at different ratios, and that gap can be relatively significant. A solar charge controller acts as the middle man, converting the power produced by the solar panel to a ratio that the battery accepts.
Two primary solar charge controllers are used on boats: Pulse With Modulation (PWM) and Maximum Power Point Tracking (MPPT).
PWM Charge Controllers are simple, efficient, and come at a lower price-point than MPPT controllers. While these charge controllers are less complex, they are better suited for solar arrays below 20 Volts and 200 Watts.
MPPT Charge Controllers have advanced technology, offering 10-30% higher efficiency than PWM controllers. Since they offer more power, they are better for solar arrays exceeding 20 Volts and 200 Watts. MPPT charge controllers also operate more efficiently in cold climates.
Whether or not you choose to wire your system together or hire a professional electrician is up to you. If you decide to wire the system yourself, you’ll need to purchase the following at a minimum:
- Waterproof Connectors
- MC4 Disconnect Tool
- Compatible Solar Panel Wiring
- MC4 Wire Crimping Tool
Need more input on choosing the right solar panels for your boat? Ask the #Boatlife community what they think today with a question or comment on our community forum!
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