We knew from the beginning that we were going to need a lot of power. For instance, our freezer was able to keep gelato frozen and the refrigerator kept the beer chilled all through the long hot summer, but at a cost of 100 amp hours a day. Our total daily electrical consumption when sitting at anchor is close to 150 amp hours. But we did not want to have to run our generator (or even worse, our engine) for hours every day to keep our batteries charged. And I don’t like wind generators. I just don’t. No, I knew our solution was going to be solar. And the best way to do it appeared to be flexible panels mounted to our bimini. We had space for 500 watts of panels, and using the lighter flexible panels mounted to the fabric bimini eliminated the need for a complicated and expensive support framework. So I set to work and drafted a design.
It took three months and the bimini had to make three separate trips back to the canvas shop for tweaks and adjustments, but we finally tightened the last screw yesterday. And I have to say, I’m in love with the results.
Here were our design criteria:
We didn’t want to put a couple of boat bucks worth of solar panels and wiring on a worn out bimini. So we retired the one Eagle Too came to us with and had a new one made.
We used Sunbrella Supreme rather than regular Sunbrella, because we wanted a truly waterproof bimini. The old one would only slow the rain down rather than stop it, and Sunbrella depends on a coating for its water resistance, which eventually washes out. While the top layer of Supreme appears the same as regular Sunbrella, its softly flocked underside makes it truly waterproof.
We wanted the panels to be mounted securely enough to hold up to pop-up thunderstorms and their brief 50 knot winds, but easily removable in case a severe or tropical storm is predicted. I didn’t want to depend on Velcro, because I didn’t trust that the adhesive holding it to the panel would survive the tropical sun. Do you have any idea how hot a black panel gets in full sun? Plenty hot enough to melt adhesive.
Six panels meant a lot of wiring, and we wanted the bimini to organize it in a way that made everything look neat and orderly rather than like an explosion at a spaghetti factory.
Tony Renbarger of Coastal Canvas of Pensacola took on the challenge, and met every one of our requirements. i think his solution to our mounting problem was quite elegant. His research led him to a fastener from Australia we’d never seen before called a Stayput. The moment he showed it to me, I knew it was exactly what we were looking for. The post on the fastener fits the grommets in our panels perfectly, and once you flip down the key, they lock the panels in place by jamming against the grommets if the panel tries to lift. For extra security, I purchased some stainless steel E-clips from McMaster Carr and used them to lock the keys in place.
The hardest part of using these fasteners is that you have to get the placement exactly right. The smaller 50 watt panels we used on the aft end of the bimini only had four grommets, one in each corner. But the larger 100 watt panels have eight, four down each long side. Tony wasn’t sure he could get that many to line up precisely, so we only used the Stayputs on the four corners. I then had him sew some fabric loops into the top, and we used black parachute cord to secure the center grommets. This securely holds the center of the panels down, but will be very easy to remove if necessary.
Some strategically placed Velcro tabs and two boots on the bimini trailing edge manage all the wiring.
Even though the panels are only a few pounds apiece, their combined weight was causing the bimini to sag just a bit in the center. So we added a spreader bar between the center bows to keep the top taunt.
And Tony found some nylon standoffs to keep the bimini frame from rattling against the new siderails we had installed when the wind blows.
Using two smaller 50 watt panels on the aft end of the bimini left us plenty of room for a larger viewing window to let the helmsperson keep an eye on the sails.
A word about the panels we used. They’re from King Solar, and we purchased them on Amazon. Since we have Prime, they shipped for free, which is pretty amazing when you consider that they came all the way from China. We bought four of the 100 watt panels, and two of the 50 watts. The 120 watt panel they offer was actually a bit too long to fit our bimini, while the dimensions on the 100 watt fit our top exactly. There were two things I liked best about the King Solar panels (besides the incredible price). First, they radiused the corners, making them friendlier to fabric biminis. Some other models have square corners, and are wicked sharp and will tear or poke a hole in fabric if given the chance. Second, they mount their diode boxes on the underside of the panels rather than on top, which offers them a little more protection from the weather. We had Tony add some squares of extra fabric under where the diode boxes would sit to eliminate chafe.
So after probably six months of research and planning, and another three of construction and alteration, we finally have the top we’ve been wanting. In full sun, we should get from 30 to 35 amps of DC power from this design, which means it should only take four to five hours of sunlight a day to make all the electricity we need. And you know what’s really amusing about all this? SInce our boat is our primary (and only) residence, then due to our crazy tax laws, the American taxpayer will be providing us with a hefty tax credit to pay for the cost of our new bimini and installing solar panels on our yacht. Is this a great country or what? 🙂
We’ll have another post in the near future that details the specifics on the controller we’re using and how we’re wiring into our existing charging system. It will be the next installment of our More Power, Scotty! series. Till then…
What type of electrical connector do you have between the panels showing in several of the pictures. (Has a red wire coming out of one side). Is it made for quick disconnect? If you need to remove the entire Bimini how do you disconnect the wiring?
I need to connect my outboard to the house battery and the PO hard wired it, but I need to be able to take it on and off, so would like a weatherproof easily removed connector. I’d like to integrate a smaller solar panel in my solution too. (Nowhere near what you’ve done, but along the same lines)
I’m enjoying you’re posts. Thanks for taking the time to write them.
I used MC4 connectors. They’re widely available from everyone from WalMart to eBay. I ordered mine from Amazon. They’re widely used for solar panel connections. They’re crimp fittings for wire up to 10 AWG and are rated for 30 or 40 amps, so you could use them for the output from an alternator on the outboard, but I don’t know if they’d be robust enough for the power to the starter. They’re designed to be weatherproof, and have O ring seals. But they’re not really what I’d call quick disconnect. They’re designed not to pull loose, and have positive locks that use a special tool to disconnect. If we have to fold up the bimini for a storm, we’d use the tool (I bought two) to disconnect all the connections, pop the panel mounts loose, and remove the panels and stow them below, and then fold up the bimini and zip on the boot.
This is a great write up and is exactly what we want to do.
Could you please shed some light on how the stayput fasteners were attached to the bimini fabric?
They press in with a rivet tool. Each fastener has two small metal posts on the bottom that pass through small holes in the bimini, and then a metal button is pressed onto each one from the underside with the rivet tool. It gives a neat, finished appearance from the underside, and in four months of cruising, none of the fasteners show any signs of leaking or working loose.
Thank you so much for your wonderful post. I’m considering building a new bimini top with incorporated solar panels just like what you had made. Some people suggest that panels that are mounted on a non-rigid surface and continue to flex will fail quicker, and that backer panels (8 mm polycarbonate is their suggestion) are needed. This would double the weight of the panels. What say you? Any comments about your panels’ performance so far?
Adding a backer panel would obviously increase the weight of the panels. We already had to add a spreader bar to the bimini to reduce the sag from the panels. I’d just pay attention to the radius of the bend applied. I’ve seen some flexible panel installations on biminis where the panels don’t quite fit and they end up having one or more corners bent down too tightly to make them conform to the bimini. Anyway, with the drop in cost of flexible panels, the panels themselves were actually the cheapest part of the installation. The new bimini, charge controller, and associated wiring all cost as much or more than the panels themselves. So if the panels do fail in a couple or three or four years, I’ll just replace them with better, cheaper ones.
I’m considering doing what you have done but on a smaller scale – only 1 100W panel. Everything I read indicates the King Solar panels are good quality panels. After several years of having your installation, how would you rate the panels now? Also, can you give me an approximate thickness of the panels. I’ve looked all over and can’t find that particular dimension – I can find the width and length fine, but not the thickness.
I really can’t recommend the King Solar panels. Ours are four years old now, so they might have improved, but the ones we have haven’t held up as well as I would have liked. They used a spray on UV coating that flaked off in the first six months. The clear plastic top surface then began getting milky and opaque, and I’ve had to periodically clean the haze off. The plastic is also getting a little brittle, so the panels have lost some of their flexibility. I had one crack the top layer when I tried to remove it last year for an approaching hurricane. I’ve since seen that there are panels for just a few more dollars each that use a flexible aluminum bottom layer and a true UV proof top layer, so I’d probably go with an upgraded panel over the King Solar, particularly if I were only buying one.
Can you provide the part umber of the stainless steel E-clips?
It’s been five years, and I can’t recall if we used 3/8th or 7/16th. Just measure the stud diameter on the fasteners and then use the same size. We bought them from McMaster, I do remember that much.
Thank you for posting. I am in the process of installing our solar panels on our bimini. Can you able to recall the diameter of the post of the stayput clip you used? I am on their website but can’t see that detail. As it has been some time now since you created this set up, are you still happy with it?
Many thanks for your help.
The fasteners worked very well, and even held tight during the 100 mph winds of Hurricane Sally. One actually ripped out of the Bimini without releasing the panel. It was probably overkill, if we did it again we’d probably just have fabric loops sewn to the Bimini and tie the panels down with laces.