When trying to determine which marine solar solution is optimal for your needs, it is often hard to decipher the wood from the trees.
One question I regularly get asked is how good flexible marine solar cell panels are and whether flexible is worth the extra cost to install them on a boat.
In this article, I compare rigid against flexible marine and discuss the pros and cons of these two types of solar panels, helping you decide on what’s better.
1️⃣ Choosing between Rigid and Flexible Marine models depends on your needs.
2️⃣ Rigid ones are cost-effective with better power generation if space isn’t an issue.
3️⃣ Flexible models are suitable for limited space, though less efficient. They’re also more durable in rough sailing conditions.
⚖️ The Differences Between Rigid And Flexible Solar Panels
The differences between the two types are flexibility, mounting method, airflow, weight, cost, efficiency, life expectancy, and power production in the shade.
In this context, solar panels that can be formed to the shape of a roof give the installer greater flexibility in mounting positions.
Unlike rigid types, which must be installed on a flat or near-flat surface, flexible ones can conform to the shape of a cabin roof, deck, or other mounting points.
Rigid solar panels are adhesive as they use a series of fixed mounts screwed into a solid, flat surface, which can be very convenient on an RV or big yacht.
On a boat, this can be a challenge for the solar installer because there may not be enough “solar real estate” to install the required number of rigid solar cell panels, whether it’s a flat or curved surface.
Overcoming this will require creative thinking, including opting for fewer, more powerful models. Alternatively, many owners build a separate solar panel rack over the davits at the stern.
A flexible type of solar panel can be installed in numerous different ways, which include:
- Being sewn into a Bimini or other canvas roof.
- Gluing them onto a cabin roof that is not flat.
- Installing them on different sections of the upper deck.
🎓 Learn More: You can dive deeper into this topic in our marine solar panel installation guide.
The one upside of the systems used to install rigid solar panels is that they are held away from the base on which they are placed.
This allows a free flow of air behind the panels, which helps to prevent them from overheating.
Flexible models could also be placed on frames in this manner; however, it would remove the main benefit, which is the ability to mold the panel around differing shapes.
Rigid panels are significantly heavier than flexible panels.
To put this into context, 200-watt flexible panels will generally weigh between 4 lbs. and 8 lbs.
The same power output rigid panels weigh between 30 and 50 lbs.
Using rigid panels, a four-panel system would add 120 lbs. to 200 lbs. to your vessel. The equivalent system using flexible panels would add between 16 lbs. and 32 lbs. for the same power output.
Rigid panels tend to cost significantly less than a similar output flexible panel.
Depending on the technology used in the flexible panel, the prices for a 200-watt panel vary from $250.00 (Vicemob Monocrystalline Silicon) to $580.00 (BougeRV 200W CIGS Thin-Film Flexible Solar Panel).
The equivalent rigid type will cost $168.50 (Newpowa 2 Pieces 200 Watts 12 Volts)
Solar Panel Efficiency
Although advances have been made, flexible panels remain less efficient than rigid types.
The efficiency of a panel is the percentage of solar energy it can absorb and convert into electrical current.
While they may have the same rated power output (say 200w), a higher-efficiency panel will require lower-intensity sunlight to achieve the output.
Rigid solar panels’ efficiency ranges between 21% and 27%, depending on the brand.
Flexible models can only convert between 13% and 22.5% of the solar radiation they are exposed to.
Under normal circumstances, a rigid type will have a longer lifespan than a flexible one. On a boat, this rule may not hold true.
Fixed solar panels will be exposed to far more movement than they are designed for. Potentially resulting in micro-cracks developing in the silicon wafers, reducing their performance.
This means that flexible models may have a longer life expectancy than rigid ones in a marine environment.
Power Production In Shade
Flexible solar panels suffer less degradation in shady conditions compared to rigid types.
Flexible panels lose between 10 and 20% power in the shade compared to 60 to 80% with rigid panels.
🎯 How To Select Between Flexible And Rigid Solar Panels?
Solar systems and boats seem to be a marriage made in heaven.
This is usually true. However, the system must be designed around the variables associated with each installation.
The effect of these variables listed below will affect the performance of the panels. This means that where they are installed in a position that is not optimal, much higher power-rated (watts) panels will be needed.
Where conditions are ideal, there is no reason to over-invest and purchase more powerful panels than are needed. Here’s how much solar is needed for a boat to give you a better idea.
The Solar Panel Set Up
The position, angle, temperature, location, and season affect their efficiency.
Insolation (Solar Radiation)
Insolation is the measure of the solar radiation that reaches the panels and is affected by the sun’s angle, air mass, length of the day, cloud cover, and pollution levels.
If you sail in the tropics, a solar power system powered by flexible panels may be optimal because the insolation levels are high.
If you’re cruising around in an area with continuously bad weather conditions, you will want to ensure that they achieve maximum efficiency. This would point to rigid panels.
Irradiance (Power Of The Sun)
Irradiance is the sun’s power (watts,) which arrives at the panel’s surface anytime. This is an extension of the Insolation.
If your boat is used in the extreme Southern or Northern latitudes, maximizing the solar energy captured by the panels is important.
This will favor rigid panels.
They work most effectively at 77 degrees F (26 degrees C). If the temperature varies, the efficiency of the panel is compromised.
In a hot climate with long periods of sunlight, it might be important to maximize the airflow around and behind the solar panels.
This situation will favor rigid models.
Solar Panel Orientation
The orientation of the panels to the sun is a significant influencer on the performance.
South of the equator, the panels must point North, and the North of the equator, panels, point South.
If you’re cruising between the Southern and Northern latitudes, I recommend building a rig on which the panels can be reorientated to take into account the different positions of the sun.
Rigid ones would be more suited for this kind of adjustment.
🏆 Final Verdict
Although the technology is older, rigid monocrystalline silicon PV panels are usually the ones that still offer the best return on investment (ROI) for marine solar systems.
The high solar yields mean fewer panels are needed to do the same work as flexible panels, and the lower cost makes for an easier cost/benefit analysis.
|Life Expectancy (Normal Conditions)
|Life Expectancy (Harsh Conditions)
|Power Production in Shade
❓ Frequently Asked
Which Solar Panels Are Best For Boats?
If yours has ample space, then rigid models offer the best solution. The only time this does not hold true is if space is an issue.
If that is not the case, and the size and shape of the boat require the panels to be formed around parts of the structure, flexible panels will be the optimum choice.