Selecting Solar Panels for Your Boat

Most solar panels today are monocrystalline. Polycrystalline technology has been largely phased out. If your boat has older panels, swapping to modern monocrystalline is often the single easiest way to increase yield from an existing system. Within monocrystalline, there are several technologies to consider, each with different tradeoffs for the marine environment.

One thing holds true across all panel types: wattage-per-square-foot is fairly consistent within a technology tier. Quality matters at the margins, but the relationship between panel size and output is predictable. You will not see dramatic differences between reputable manufacturers within the same class.

Standard Panels

Standard monocrystalline panels are the most common option and are widely available in a range of sizes, from a few tens of watts up to several hundred. As panels get larger they produce more power, but fitting them on a boat becomes more challenging. They come in both rigid framed and flexible varieties, with flexible panels being lighter.

The most important feature to look for in a standard panel for marine use is bypass diode design. On a building, nearby obstructions rarely move, so shading is predictable and panels can be placed to avoid it. On a boat, the vessel is always moving, rigging passes overhead, and partial shading is a frequent reality. A panel without bypass diodes on each cell string can lose more than half its rated output from a shadow covering only a small fraction of its surface. Even a single line of rigging shadow crossing the panel can cut performance dramatically. This is also why keeping panels clean matters more on a boat than on shore: a streak of salt or a bird dropping is functionally the same as a shadow.

Note that even flexible panels perform best when mounted flat. Significant flex reduces output and, over time, stresses the cells.

Bifacial Panels

Bifacial panels collect sunlight from both the front and rear faces. On land with a reflective surface beneath them, gains of 10–20% are achievable. On a boat, realistic gains are typically 5–10% (the deck is often dark, and the water's surface scatters light chaotically rather than reflecting it cleanly upward). Some manufacturers include a portion of the bifacial gain in their nominal wattage rating; others advertise it as additional yield potential. Either way, treat the upper end of any bifacial gain estimate with skepticism in a marine context.

The critical caveat for boats: the rear face needs clear exposure to produce anything useful. In a marine environment, the underside of the panel picks up light scattered off the deck and, to a lesser degree, off the water's surface (though water tends to scatter light in an unpredictable pattern, limiting how much the rear face benefits). Whether bifacial panels are a worthwhile upgrade depends almost entirely on how the panels are mounted. A panel lying flat on a solid deck gains little from the rear face. A panel elevated on a frame or arch mount where light can reach the underside is a much better candidate.

Bifacial panels are almost always rigid framed. A small number of flexible bifacial options exist, but they are uncommon, since mounting a flexible panel in a way that meaningfully exposes the rear face is difficult in practice.

Maxeon and Back-Contact Panels

The IBC (Interdigitated Back Contact) cell technology behind Maxeon panels was originally developed by SunPower. Maxeon Solar Technologies, now headquartered in Singapore, was spun off from SunPower in 2020 and continues to produce these panels under the Maxeon brand. Rather than adding a rear-collecting layer, Maxeon panels move all of the busbars and wiring to the back of the cell. This eliminates the metal grid lines that normally shadow the front surface of a standard panel, maximizing the active light-collecting area. The result is significantly more power per square foot than a standard monocrystalline panel of the same size.

Because the back of the cell is occupied by the electrical contacts, Maxeon panels cannot be made bifacial. That is generally not a problem: a single-sided Maxeon panel frequently matches or exceeds the output of a bifacial standard panel, without the mounting constraints bifacial requires. Other manufacturers produce back-contact panels with similar characteristics, but Maxeon is the most established name in this category and the benchmark against which others are measured.

Maxeon panels are available in both rigid and flexible form factors.

Flexible Panels

Flexible panels offer a meaningful weight advantage and can conform to curved surfaces that would not accept a rigid frame. Some are rated for foot traffic, though we do not recommend walking on them: the surface is glass-like and will be slippery when wet.

The performance tradeoff is real. Flexible panels produce slightly less power than an equivalent rigid panel, and output drops further if the panel is mounted with any significant curve. For installations where weight and profile matter more than maximum yield, they are a sound choice. For installations where you want every watt, rigid panels or Maxeon flexible panels are worth the added weight.

We design and fabricate custom mounting frames that let you get the weight advantage of flexible panels while keeping them flat enough to perform like rigid ones. If you are trying to maximize output from a difficult mounting location, that is often the right solution.