Solar On Board: 3D-Printed Panel Mounts, Wedges and Cable Entries
Solar is the easiest power upgrade on a boat, and the panel itself is rarely the problem. The problem is everything around it: the bracket that holds it at the right angle, the standoff that lets air pass underneath, the clamp that grips a 25 mm rail, the wedge that stops a rigid panel flexing on a curved deck, and the little cover that keeps water out of the hole you drilled for the cable. That hardware is either unavailable in the size you need, sold as an expensive aluminium kit, or shipped from the other side of the world for a part that weighs 40 grams.
This is exactly the territory where 3D printing earns its place. None of these parts carry the boat, none of them are structural in the way a chainplate is, and every one of them is dimension-critical — which is why sized-to-fit files beat a generic bracket every time.
The four parts that actually matter
1. Rail clamps
The most common mounting job on a sailboat or a RIB: a semi-flexible panel hung on the pushpit or a guardrail. A printed clamp is two halves that close around the tube with a stainless bolt through each side. What matters is the internal diameter. Marine tube is usually 22, 25, or 30 mm; getting it wrong by half a millimetre means the clamp either won't close or slips under load. Measure the tube with a caliper, then print to that number — not to what the catalogue says the tube is.
Add a strip of TPU or a scrap of inner tube inside the clamp jaws. It stops the plastic polishing the stainless, kills the rattle at anchor, and takes up the tolerance you couldn't measure.
2. Tilt wedges and standoffs
A panel lying flat on a coachroof runs hot and loses output. A 15–25 mm standoff underneath restores airflow and can recover a noticeable slice of yield on a hot, still day. Wedges do the same job with an angle: a set of four printed wedges at 10° or 15° tilts a panel toward the sun without a fabricated frame.
Print wedges solid, or close to it. This is one of the few places on a boat where infill genuinely matters — a wedge is in permanent compression under a panel that's being lifted and dropped by wind. 40–60% gyroid or higher, and orient the part so the layer lines run across the load, not along the joint you're relying on. Our guide on print orientation and strength covers why the same wedge can be twice as strong depending on how it sits on the bed.
3. Corner brackets and edge caps
Semi-flexible panels crack where they flex — usually at the grommet holes, because the panel bends around a hard fastener. A printed corner cap that spreads the load over 40 mm instead of 6 mm is a five-gram part that adds years to a panel's life. Same idea for edge trim on a rigid panel mounted over a bimini.
4. Cable entries and gland covers
The hole you drill for the solar cable is a deck penetration, and it deserves the same respect as any other. A printed gland cover — a low dome with a downward-facing exit and a sealant channel — keeps green water out and looks far better than a blob of silicone. Make the exit face aft or down, never up. More on the wiring side in our post on cable clips, combs and gland covers.
Material: this is a UV job, not a strength job
Solar hardware sits in full sun, all day, every day, by definition. That single fact decides the material.
| Material | On a solar mount |
|---|---|
| PLA | No. It creeps under sustained load and softens in a hot cockpit. A tilt wedge in PLA will slowly flatten. |
| PETG | Fine for shaded parts and cable covers. Yellows and gets brittle after a couple of seasons in direct sun unless coated. |
| ASA | The default choice. Genuinely UV-stable, holds up in the heat under a panel, prints in an enclosure. |
| PA (nylon) / PA-CF | Best for rail clamps that get torqued hard. Keep it dry before printing and expect it to absorb moisture. |
If ASA isn't an option, PETG plus a UV-blocking topcoat gets you most of the way. We compared the trade-offs in detail in making prints UV-resistant for the deck and in the wider materials guide.
Fastening: don't thread into plastic
Every printed solar bracket should bolt through, not screw in. A machine screw through a clearance hole into a stainless nyloc, with a washer under the head to spread the clamping load, will outlast a self-tapper into printed plastic by an order of magnitude. Where you need a threaded hole — an adjustable tilt leg, for instance — use a brass heat-set insert rather than printed threads.
Two practical notes. First, do not overtighten: printed plastic creeps, and a bolt torqued hard on day one is loose by autumn. Snug plus a nyloc, then check it after the first month. Second, isolate stainless from aluminium panel frames with a plastic or nylon washer — the printed part can do that job for you if you design it that way.
A realistic weekend plan
- Measure first. Rail OD, panel frame thickness, grommet spacing, cable diameter, and the deck curvature under the panel. Write them down.
- Print one clamp, not eight. Test it on the actual tube before committing a spool. Tolerance is the whole game here — see our tolerance calibration guide.
- Dry-fit the panel with clamps hand-tight and check the panel clears the boom, the sprayhood and the winch handle arc before you drill anything.
- Drill and seal the cable entry last, once you know exactly where the junction box ends up.
- Print a spare of each part. They weigh nothing and they're the parts you'll want at anchor, not at home.
Where to start
Parametric brackets, clamps and covers sized to your own measurements are in Navigation & Electronics and Deck & Rigging. Fasteners, spacers and bushings that pair with them are under Tools, and if you want to try the workflow before spending anything, the free files are a good place to start.
A word on limits
3D-printed parts are not certified marine equipment. Solar mounting hardware carries wind load — a 100 W panel on a pushpit is a sail, and a bracket that fails at 35 knots becomes a projectile. Use printed parts for mounting, spacing, protection and cable management; use metal for anything that would injure someone or damage the boat if it let go, and never rely on a printed part below the waterline or in a critical system. Check your material and your fit before the part goes to sea, and inspect it at the start of each season.
Questions about a specific panel, rail size or deck layout? Write to info@marinelab3d.com — if the part you need isn't in the catalogue yet, tell us the dimensions and we'll look at adding it.