Groovy's solar panels.
Happy panels in full sun, Sea of Cortez.
Full sun & no shade (3 panels working): 22.5 amps
One panel partially shaded (2 panels working): 15 amps.
Shade straddles two panels (only 1 panel working): 9.5 amps.
Polished welds and drilled/tapped/screwed joints.
Comparison: Factory weld on our Hunter arch.
The arch extension arrives for a fitting.
Alejandro tie-wraps it in place.
Mark helps hold it up.
The extension is in place -- without its legs yet.
Jose checks if it's level.
The arch extension returns -- now with support legs.
It's maneuvered into place.
Telescoping davit arm (marine solar panel arch)
Held in place with tie-downs.
Alejandro drills and taps holes in the arch.
The solar panels are ready!
Arch extension removed from Groovy while Alejandro drills
and taps the arch on the boat.
The second panel is installed.
Three panels - yay!
Alejandro and Mark test the strength of the arch extension.
Mark begins the big job of wiring it all up.
Component layout: 3 panels, combiner
box, controller & 4 batteries
Combiner box (upper left) and controller (lower right).
Wiring the panels.
In use 18 months later in Puerto Vallarta.
Sailing in Huatulco.
Sailboat Solar Power & Solar Panel Arch Installation
This page describes the solar power setup we installed on Groovy, our Hunter 44DS
sailboat. This was our third solar installation. Our two RV solar installations are described
on the RV Solar Setup page.
We learned a lot from those installations. The first one taught us the basics about the
components used for generating and accessing solar power in a moveable home. The
second installation taught us two things: (1) the importance of wiring panels in parallel
rather than in series if there is any possibility of the panels ever being shaded (all the
panels essentially shut down if only one is slightly shaded); and (2) the value of being able
to tilt the panels towards the sun in the winter. We took the lessons we learned and
turned them into a multi-part Solar Installation Tutorial for RVers and sailors.
The company Kyocera
Solar liked our solar
panel installation so
much, they featured
For comparison, our solar power installations have consisted of
(1) 130 watt/12 volt Kyocera solar panel
Various 150 watt to 800 watt portable and
semi-portable modified sine wave inverters
(2) Energizer 6 volt batteries in series (220 amp-hours).
(1) 130 watt/12 volt Kyocera and (3) 120 watt/12 volt Misubishi solar panels (490 watts total), wired in series
(1) 900 watt "pure sine wave inverter permanently mounted
(4) Trojan 105 6 volt batteries wired in series and in parallel (440 amp hours).
(3) 185 watt/24 volt Kyocera solar panels (555 watts total), wired in parallel
(1) Combiner box (combines 3 panel wires into 1 going to the charge controller)
(1) Xantrex 60 amp MPPT charge controller
(1) Xantrex 2500 watt modified sine wave inverter/charger
(4) Mastervolt AGM 4D batteries, (1) Group 27 AGM battery (710 amp-hours)
Notes: (1) Our odd collection of panels on the Hitchhiker was due to the Kyocera 130 panels not being available at the time of
our installation (we brought one over from the Lynx). (2) Our switch from the Outback to the Xantrex charge controllers between
the Hitchhiker and the boat was due to the Xantrex being cooled by non-moving fins rather than a fan. In hindsight I would
probably use the Outback charge controller in the future only because it displays more information on its screen rather than
having to scroll through multiple screens to get the voltage, amperage, watts and charging stage. (3) Our Group 27 start battery
on the boat is isolated from the set of 4D house batteries only when the voltage of the bank drops too low.
The boat has a DC refrigerator and a DC freezer which together eat up some 100-130 amps or more every 24 hours, depending
on ambient temperature. In addition we listen to music on the stereo with multiple speakers and a large subwoofer, we watch
DVD's many nights on a 22" TV, we use two laptops for several hours everyday. We also have a water pump, electric flush
heads and VHF radio which we use at anchor. Our cabin lighting is a combination of fluorescent and LED, and our anchor light is
LED. So our typical daily amperage use at anchor is between 180 and 250 amps.
In December, around the winter solstice, on the southern mainland of Mexico (Zihuatanejo) our solar setup collected about 170
amp-hours per day. In June, around the summer solstice, in the middle of the Sea of Cortez (San Carlos) our solar setup
collected about 250 amp-hours per day. In hindsight, it would be nice to have at least 750 watts of solar power to meet our
power demands in winter.
PARTIAL SHADE KILLS SOLAR POWER PRODUCTION
The biggest problem with installing solar power on a sailboat is accidentally getting a little shade on the panels. While swinging at
anchor, the mast, boom, radome and other things high up all conspire to throw pockets of shade on the solar panels and make
them quit working. It is quite shocking to find out just how little shade is needed to reduce the panels to zero output. We had
experimented a bit with partial shading issues on our fifth wheel solar installation (see bottom of Solar Setup), but we never park
near shading objects so it is not a problem on that moveable home. A sailboat is a whole different story.
An interesting paper Shade Effects on Conventional PV (5th article down) from the Physics Department at the University of
Arizona describes how shading just half of one row of "squares" on a solar panel -- as often happens in the morning or afternoon
hours on a commercial installation if the rows of panels are placed too close together -- the panels shut down or reduce their
output significantly. The opening sentence says it all: A panel that is 8% shaded loses 94% of its productivity." Deep down in the
meat of this paper the math lost me (sigh), but for a layman's explanation of just how devastating shade can be on solar panels,
this website delivers the skinny.
We placed our panels as high and as far back from the boom as we could. We also pull the boom aside while at anchor, but the
panels still get shaded by the mast/forestay/radome when the sun is forward of the shrouds and they get shaded by the sails
when sailing. As an experiment, we took some notes about how partial shade affects our panels. This data was taken on
February 3rd at 10:00 a.m. The shade was caused by the mast, forestay and radome (affixed to the front of the mast). The
shade moved slowly back and forth across the panels as the boat swung at anchor.
Panels in full sun:
One panel partly shaded:
Two panels slightly shaded:
As another experiment we sailed and noted the amperage
produced by the solar panels as we sailed on two different
tacks. On one tack the mainsail shaded one entire end panel
and half of the middle panel. On the other tack the boat was
heeled away from the sun but there was no shade on any of
the panels. It was far better to be heeling away from the sun
than to have the panels shaded. This data was taken at 11
a.m. on January 31.
1½ panels fully shaded by sails:
No shade, tilted away from sun:
So it seems to me that shade is the number one enemy of solar panel power production on a sailboat, and orientation towards
the sun is a lot less important. If the solar panels are installed in such a way that a nearby radome or wind generator is always
partly shading one panel in the array, as too often happens in solar panel installations on sailboats, the result will be dramatically
reduced power production.
THE ARCH EXTENSION
Our boat came with a fantastic arch that supports the traveler. We used it as a base for an elegant stainless steel extension that
supports the three panels. We hired Allejandro Ulloa of Ensenada, Mexico to create this arch extensions. Alejandro is an artist
and a master craftsman. And he is extremely professional. We gave him a sketch of what we were looking for, he responded
with a written quote for half of what it would have cost in San Diego, and we were off and running.
Alejandro prides himself on the beauty of his work. He polishes the welds and installs tubing that
seems to flow like liquid metal as it rounds corners and changes thicknesses. In our opinion, his
arch extension dramatically increased the esthetics of our boat. It also added functionality
besides just supporting the panels. It makes a great spot for hanging on when you're sitting in
the rear jump seats, it has a
telescoping davit system,
and the panels provide
much needed shade.
If you need to have an arch
or any kind of stainless steel
structure fabricated for your
boat and you are heading to
Mexico from the US or
Canada, spend some time in
Ensenada and look up
Allejandro Ulloa (email:
alejandrossw [at] hotmail [dot] com,
Mexican phone: (646) 171-5207). He can
be contacted through the excellent Baja
Naval boatyard as well. There are other
stainless steel fabricators in Mexico but we
haven't seen anyone nearly as skilled or
as professional in their approach.
Alejandro built the extension in his workshop and then brought it
to the boat to size its supporting legs. This was a thrilling process
for us, as we began to see it taking shape on the boat. The entire
arch extension was wrapped in plastic for this phase to protect
Mark helped wherever he could and I took endless photos.
Alejandro returned on another day with the finished arch extension.
Now it had tabs for the solar panels, and the supporting legs had
been cut and welded at the right length.
We wanted the arch extension to double as a davit system.
Alejandro designed clever telescoping tubes that snap into place in
an extended or contracted position, and he fabricated two beautiful
cleats. We have found that we use the davits in the contracted
position most often because they hold the porta-bote tight to the
swim platform where it fits perfectly into the swim step cutout in the
mounting the solar
as the quote
was for building
and installing an
not for installing
weren't sure how
we'd get them mounted, but we knew
we'd figure it out.
Meticulously adhering to the
"measure twice cut once"
dismantled the whole thing
for some adjustments and
then mounted it one last
time for the final installation,
tapping and drilling and
screwing each of the arch's
feet into place in a bed of
Then, to our amazement,
Alejandro and his assistant
began mounting each of
the panels. Mark quickly
jumped in. These are not
light panels, and it was
quite a stretch to get them
in position. Alejandro was
concerned about possible
corrosion due to the
dissimilar metals of the
panels' aluminum frames
and the stainless steel arch
extension, so he placed a
plastic insulator in each
When it was all
wanted us to be
confident that the arch
could support a dinghy
and engine. He and
Mark swung from the
davits. Both are
lightweights, but they
were still twice the
weight of our
Alejandro's work was done, but we still had a big project ahead. We ran the wiring
inside the arch so it wouldn't show (it wasn't easy snaking it through!!), and we placed
and it worked, but it did not work as efficiently as it
could have. The whole system produced about
20% less power each day than it was capable of
doing. We learned we'd made two vital mistakes.
One advantage of using 24 volt solar panels is that
we had half as much current in the wires as we
would have had if we'd used 12 volt panels. Rather
than 36 amps (at 12 volts) at peak production we
had just 18 amps (at 24 volts). This allowed for a
smaller wire size, which is much easier to work with
as it is a lot more pliable, and it's cheaper to boot
(marine grade electrical wire is exorbitant). Our
salesman at Northern Arizona Wind and Sun had recommended we use 10
gauge wire throughout the system. This turned out to be inadequate
because the distance between the panels and the batteries is so long --
about 50'. For wire gauge sizes, amps and
distances, see this chart.
Our second mistake was placing the charge
controller in an aft transom locker. Our batteries
are next to the centerline of the boat at the lowest
point above the keel in the main salon. The
charge controller needs to be close to the batteries
as possible. The distance from the charge
controller in the transom locker to the batteries
was about 30' -- too far. The combiner box was
fine back there, but the charge controller had to be
Although most of our circuit runs at 24 volts -- from
the panels to the combiner box to the charge
controller -- allowing for smaller wire, the portion
between the charge controller and the
batteries runs at 12 volts. Therefore, the
cable between the charge
controller and the batteries
needs to be not only as short as
possible but very large as well.
We moved the charge controller
into the cabin in a hanging
locker about 10' from the
batteries and and switched to 8
guage wire to connect it, and we
saw a dramatic improvement.
When the distance between the
charge controller and the
batteries was 30' and we were
using just 10 gauge wire, the
resulting resistance in the wire created a large
voltage drop between the charge controller and the
batteries, artificially raising the voltage at which it
thought the batteries were operating. The charge
controller would see the batteries at 14.4 volts whereas when we measured the batteries with a volt meter
they were actually at 13.2 volts. This threw everything in the system way off, and ultimately resulted in a
daily loss of some 10-30 amp-hours that never made it from the panels to the batteries. Once we moved the
charge controller to within 10' of the batteries and installed bigger wire, the resistance dropped. The
controller saw the batteries within 0.2 volts of their actual voltage, and our daily power production increased.
Note: In three years of cruising Mexico, our boat was plugged into shore power for a total of 6 weeks
while it was in in-water storage in San Carlos. It was never plugged in while we lived aboard (even during
the 3 months we stayed at Paradise Village Marina in Puerto Vallarta).
The solar power setup aboard Groovy has inspired stories and articles all over the internet. Here are a few of the websites and online magazines that have featured stories about Groovy and our marine solar power installation:
Where do you buy solar panels, charge controllers, inverters and such? Surprisingly, Amazon offers solar power kits and more. Click the following links for a wider selection of:
- Solar power kits (all sizes)
- Morningstar Charge Controllers (for small "weekender" systems)
- Outback charge controllers (for big "full-timer" systems)
- Modified Sine Wave Inverters (for small "weekender" systems)
- Pure sine wave inverters (for big "full-timer" systems)
We receive a 4-6% commission for any Amazon purchases made through links on our site. This helps us cover our out-of-pocket expenses for keeping this site running, and we extend a huge "thank you" for shopping through us!
Want to learn more about how to design and install solar power on your boat?
Read our SOLAR POWER TUTORIAL
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