The Solar-Tracker (Sold Out Nov 2012)
Fully adjustable solar panel mounts to track the sun for maximum efficiency
The original Solar-Tracker mounts have been with Atom over ten
years and survived serious weather off the Cape of Good Hope
My philosophy for a small cruising sailboat's electrical system is to keep it simple: conserve power usage, carry a large battery bank for reserve power storage and a minimal solar array that can be directed at the sun when needed for maximum efficiency. Conservation of power comes by using only LED lights (in cool climates where some cabin heat is welcome, use backup kerosene lamps), use manual pumps instead of electric and limit the number of optional electrical appliances and gadgets.
Ideally, a dependable and practical electrical system on a small boat in the tropics should require no more than two well-placed 50-watt panels. Even one panel may be adequate on boats without radar, water maker, SSB transceivers, refrigerator, large multi-function displays, electric autopilot and other high load equipment. The ability to point the panels at the sun three or four times a day using a Solar-Tracker type design means you can increase your panel's output by at least 30%. Having the panels aft of the boom and backstay means they are in the least shaded area on the boat. When you don't need the extra output, set the tracker mounts horizontal and ignore them. This saves space and money - two items in short supply on most small cruising sailboats.
The Solar-Tracker was originally designed to fit the 13-inch wide frame of the now discontinued Siemens (Arco) 43 to 55-watt panels. Later versions of our Solar-Trackers used extended brackets to fit the Photowatt 55-watt solar panels and 54-watt Kyocera and most recently the HQRP 50-watt panels. Panels with larger footprints may not be adequately supported by this type single point mount, though it may be possible to attach a tracker mount to a Kyocera 65-watt 25.7" x 29.6" (761 sq. in. area) panel by using extra strut supports.
A pair of 54-watt Kyocera panels installed on Solar-Trackers on an
Single 43-watt Solar-Tracker on an F-27 Corsair trimaran
Solar-Tracker latest 2010 version.
Solar-Tracker installed on a Pearson 35.
A KC50T Solar-Tracker fit on a Bristol 27 in 2011.
The Solar-Tracker fits nicely even on the narrow canoe stern of this Morris Frances 26.
A pair of Solar-Trackers found their way to French Polynesia aboard this Alberg 30.
A Bristol 34 with two KC-50T Solar-Trackers.
I've fabricated and installed several trackers on our friends and customer's boats. Due to the custom fabricating and electro-polishing costs they are expensive to produce. I've stopped production as of 2013 but for budget-minded do-it-yourselfers with skills in metal working, below are photos and dimensioned sketches of the earlier version Solar-Tracker components for you to make your own. You might also have a local metal fabricating shop do the work for you. A similar Tracker kit is available from Custom Marine Products.)
I understand some sailor's concerns that one or two solar panels mounted in this way are unsightly, add windage and appear vulnerable to storm seas breaking over the stern. As to aesthetics, my view is they are no more obtrusive than larger panels mounted flat on an arch or atop a bimini, or a wind generator, a rubber dinghy on davits or much of the other gear that adorns the modern cruising sailboat. If solar panels are mounted flat on deck they have less windage and are less eye-clutter, but you lose too much efficiency through shading. I admit to a bias, but to my eye there is a beauty to their silent and dependable functionality. As I mentioned on another page, this is all subjective. When I see a solar panel on a boat, I see something no less beautiful than the mast that supports the sails; a perfect expression of passive-system energy harnessing from nature, which is the essence of sailing boats.
The strength of the mounting hardware and the small size of a 50-watt panel has proved strong enough at sea. Larger panels would be more vulnerable. The tracker panels can be removed if you expect a storm, though I never bothered to remove them and had no problem. If concerned about windage when beating, you can always feather them flat to the wind. The air flows easily around them causing no problem for windvane self-steering gear mounted nearby.
If you keep your boat in a marina and only do brief local sailing then you can get away with a simpler installation such as attaching your panel to the top of the pushpit or bimini frame. Some panels are mounted on a radar arch and may even be set up to pivot on one axis. That's better than lying flat, though it could cause a power loss of 80% or more if you're on a long tack and the panel is heeled away from the sun and shaded. People deal with that by adding more fixed panels and windchargers or motoring more often to charge the batteries. The small boat sailor would obviously find the clutter, expense and inefficiency of that system disappointing. Panels mounted in high shade areas such as on stanchions on the sides of the cockpit are useless several hours each day as one side of the boat is in shade. Boats with low freeboard may find premature corrosion or even a wave may damage the low stanchion mounts eventually.
Before mounting the panels on the Solar-Tracker, check clearance around the backstay, windvane and other gear. On the first version of my trackers I installed my panels chest high on vertical 1 1/4-inch stainless steel tubes welded onto the existing pushpit. For economy you can use two U-bolts, but for easier installation the latest model Solar-Tracker uses a special rail clamp to attach the vertical support tube to the pushpit and a universal U-bracket to fix the lower end of the tube to the deck. The wires are routed down the tube and through a deck fitting or directly through the lower U-bracket base. Plug and socket disconnects at the top allow the panels to be removed for their own protection when severe weather is expected or when the boat is put into storage. It's wise to lock them against theft or accidental loss overboard by using a cable with pad lock as shown below. Latest versions use a cable attached to a locking bolt.
More information on electrics aboard is on the Cruising Q&A page.
Do-it-Yourself version of the Solar-Tracker
Assembly notes for sketches:
Corners rounded as per sketches and all parts electro-polished.
A. Drill a 3/8" hole in tube. Then weld a 5/16" nut over hole. Clean threads with tap after welding. Bend 5/16" x 2 1/2" stainless bolt 90 degrees as shown. Insert tensioning bolt in nut.
B. Drill a 5/16" hole centered on each side.
C. On one side drill a 3/16" hole at 11/16" below other hole.
D. On one side below other two holes drill a 3/16" hole. Then using that hole drill through it making eight holes in main tube for locking pin to lock panel at eight different angles.
E. Weld a 5/16" nut on edge of main tube 1" below swivel bracket. Cut a small diameter stainless cable 23" long and crimp eyes in each end with nico-press sleeves for finished length of 19". After installation, thread one eye around swivel bracket and through other eye and lock to welded nut using small brass padlock. Use 1 1/4" main tube with length as desired between 30-40" long. Clamp main tube to pushpit horizontal rail with two 5/16" U-bolts during final assembly.
F. Drill a 3/8" hole in center. Weld tubing centered as shown.
G. Weld a 1/8" x 1 1/2" x 3" stainless plate centered as shown.
H. Begin radius 1/4" down from end and continue for 1 1/2". Brackets shown are for PhotoWatt PW 500 solar panel. Adjust length to suit other panels not exceeding 55 watt panel size.
I. Drill 3/8" holes centered in each piece. Then weld a 5/16" nut over holes on insides of angles. Clean threads with tap after welding.
J. Drill seven holes for 3/16" locking pin on one side to follow 11/16" arc radius from nut to line up with 3/16" hole (C) drilled in swivel bracket.
k. Drill 1/4" hole centered each end or as needed to attach 1/4" bolt to solar panel frame. For the PW 500 solar panel the holes are 16 13/16" apart or about 11/16" from each end.
L. Bend two 5/16" x 3 1/2" stainless bolts 90 degrees and tighten or weld nuts as shown. During assembly, insert tensioning bolts through swivel bracket and into welded nuts as shown in photos.