continuously developing. But our goal is
to prepare you to ask the right questions,
make good decisions, and get the most
out of power from the sun.
Types of panels
There are three distinct types, each
available with different kinds of silicon
cells, according to Warren, whose Bowie,
Maryland, company specializes in marine
refrigeration, air-conditioning, and solar.
Monocrystalline cells have the highest
efficiency rates because they’re cut from a
single crystal of the highest-grade silicon,
have the longest life expectancy (more
than 25 years), and require less space
because of their efficiency.
Polycrystalline (or multicrystalline)
cells, made from off-cuts and recycled
silicon, are less durable and slightly less
efficient; they tend to require more space.
Both monocrystalline and polycrystalline cells are found in the familiar hard
panels you see mounted on decks and
pilothouse tops as well as in lightweight
semiflexible and walk-on marine panels. Semiflexible panels with zippers or
hook-and-loop fasteners added to them
can be mounted in such canvas areas as
biminis and dodgers, while walk-on panels can be secured directly to a deck or
hard cabin top and absorb foot traffic. A
good way to distinguish monocrystalline
and polycrystalline solar panels is that
polycrystalline solar cells look perfectly
rectangular, with no rounded corners.
Amorphous solar panels are flexible
“roll-up” panels named after the type of
silicon used to manufacture them. These
are the least efficient but most versatile.
Solar-panel efficiency is a measurement of how much solar irradiation
the panel is able to convert to electricity. Each type has a different efficiency.
While products constantly evolve, a general rule of thumb, according to Warren,
is that efficiencies range from as low as
10 percent, for thin-film panels, to about
18 percent, for most polycrystalline panels, and to as high as 23 percent, for some
monocrystalline panels that use more
advanced technologies. This means that,
for the size, the best, most-efficient panels can produce substantially more power
than the least-efficient panels.
The cost of clean power
Of the three distinct formats of marine
solar panels, the aluminum-framed glass
panels are the least expensive, as they
use a standardized construction process.
The semiflexible and walk-on panels are
highly specialized items made in small
quantities, so they’re more expensive.
Genuine high-grade SunPower
back-contact monocrystalline cells
are currently the most efficient ones
available and give a higher daily yield,
but at a premium price. Amorphous
panels are relatively inefficient panels
and command a high dollar-per-watt
price for their ability to be placed on
“There’s a world of difference between
true high-performance marine solar
panels and those used on residential
and commercial properties. Prices reflect
that,” Warren says. “While a small
system designed just to stop a bat-
IS DETERMINED BY
THE QUALITY OF THE
tery self-discharging will cost less than
$300, a higher-capacity setup will cost in
A good rule of thumb? Buy the most
efficient panel you can afford. Many
environmental conditions (fog, smog,
clouds) can reduce the efficiency of solar
panels, and if you start with a low-effi-
ciency panel and experience less-than-
perfect conditions, you may be unhappy
with its performance.
Current output is determined by
the quality of the available sunlight.
Manufacturers provide efficiency ratings
for their panels; be sure the numbers are
derived following standard test conditions (STC), which represent the “ideal
solar conditions” for maximum performance, so that you can accurately compare one panel to another.
When installing your solar panel, choose
a place in a safe area (not where you’d
drop a winch handle). Shading can dramatically lower the panel’s efficiency, so
find a broad, relatively flat area, such as
on a cabin top or a fabricated mount,
where the panel catches the most light
most of the time. Installations that allow
air to flow underneath will improve performance, but this isn’t necessary or prac-