PRACTICAL
ABOUT THE AUTHOR
Trevor Martin has been sailing since the age
of 12, owning a Silhouette Mk2 at Chichester,
a Snapdragon 24 in La Roche-Bernard and
now his Moody 36, berthed in Plymouth Yacht
Haven. He has sailed in the Lake District,
Sweden and Malta. Most of his work has been
in children’s services and outdoor education.Re
Any misgivings J
box – ie,
I
wanted to fit solar panels to
my boat, but didn’t know
how to go about it, nor did
I know how other people
went about fitting them.
I looked at about 1,000 boats in
three marinas: now, these panels
are no works of art, yet they
dominate deck space if any real
power other than just battery
maintenance is going to be
produced. ‘Hey, look at my new
panels and associated half-ton of
tubular stainless gantry’ seems
to have taken over from ‘hey,
look at my new bird-scarer’.
I didn’t want to use the ‘less
efficient for your money’ flexible
walk-on ones as I knew that they
would get dirty and scratched at
the least; and we didn’t want to
be checking for grit on our deck
shoes when dashing for a warp,
did we? Some panels were hung
outboard, and some precluded
the use of the best sunbathing or
cocktails position. A few were even
hung vertically from the rigging:
that’s ok for sunsets or when the
boat’s seriously heeled, I guess,
but surely they kick out less when
they are at such an oblique angle
to the sun?
On my huge or diminutive Moody
36 CC, depending on who I am
berthed beside, the only area that
I didn’t stomp across was the aft
cabin roof. Due to the positioning
of the mainsheet traveller, the
tendency was to step diagonally
out of the cockpit onto the side
deck to access the stern. A quick
measurement and an hour on the
laptop showed one panel that
would just fit either side of the
aft hatch, but two of those at only
30W max each was still far off my
estimated need for 100W plus.
I just couldn’t contemplate having
Fitting solar panels
Keen to fit effective but relatively discreet solar panels to his boat,
Trevor Martin gives the matter some thought, and has a brainwave...
a stainless Eiffel Tower on my
stern, so I got to thinking. I only
wanted this power in the marina or
at anchor: when sailing, I needed
none or very little. The solution
seemed obvious, except that when
you have a brilliant idea, you have
to ask yourself: why hasn’t anyone
else done that? The idea was to
have two panels each side, hinged
so they could unfold to utilise all
four or fold flat where only twowould be in use. It got better.
With my trusty tape measure, I
realised that if carefully positioned,
a variety of arrays could be
achieved to suit the sun, the
cosmetics or a compromise.
A week later, the flaw occurred to
me. If you wire two panels in
parallel, as you should for an array
to maintain standard voltage (which
for solar is about 19V), then place
one facing down and one facing
up, will not the energy collected
from the skyward-facing one
discharge from the shadowy deck-
facing one before the current even
gets to the regulator/controller inside
the boat? Panels over 10W rarely
have a blocking diode to prevent
return flow discharge. I had this
image of a gentle glow between the
lower panel and the deck with noelectric going to the batteries, all at
great expense! Then it was pointed
out to me that the folding briefcase
caravan-type panels would suffer
the same fate, and they don’t. My
back-up plan was to put a magnetic
proximity switch between the
frames to cut off the supply from
the lower one when they were
folded, if it proved necessary, as no
one could tell me for sure what
would occur. The proximity switch
was an inspiration from when I
opened the fridge door and the
light came on, in both respects!Potential pitfalls
I will let the pictures do the talking
as plenty of worthwhile articles,
far more technical than I could
manage, have already been
published. I will however just