Top Menu

It’s been almost exactly a year since we took possession of One Love and if you recall last summer’s posts, most of the months following that delivery were taken up almost entirely by refit projects. On our initial wish list for upgrades was the addition of solar panels but with limited time and budget, that project was put off in lue of more pressing charter-related ones. This summer however, we are definitely planning on upgrading our electrical system which will include, among other things, adding solar panels. This project has a lot of variables though and I’m finding it difficult to come up with a clear plan.

Friends of ours on the charter boat Feel The Magic recently added solar panels to their boat and they were kind enough to share all the details with us. While they opted for the more-commonly-seen rigid panels, I saw yesterday that the guys on Where the Coconuts Grow opted to add the newer semi-flexible panels instead. IMO the latter look better and are perhaps easier to install. They are much more pricey though and from what I have heard, not as efficient. True?

“A day without sunshine is like, you know, night.” — Steve Martin

While it may seem that a boat as large as One Love has an almost unlimited amount of real estate to add panels, that is not really the case. I have already spent time with a measuring tape mapping out the available space on our hard bimini and with todays larger wattage hard panels running around 60″ in length, fitting a couple of them up there takes up pretty much all of the room.

Decisions, decisions, decisions. If you have a bunch of knowledge on this subject, feel free to post your thoughts.


  1. Panels work as a system. Your panel will only produce as much as the lowest producing cell. So on a curve or in shade your power development will be reduced to the lowest common denominator. So to speak. Hope this helps.

  2. Thanks for the mention, Mike! The Aurinco panels are rated for ~20% efficiency due to the design and newer technology. There are some ‘flexible’ panels out there that are much less durable and considerably less efficient. We’re interested to hear the comments though!!

  3. Hey Mike, read through your entire blog over the last month and just wanted to say thank you for taking the time to enrich the lives of us waiting 4 more years to cut the dock lines! We are live aboard for the last 3 years on a trawler and can’t wait to anchor next to y’all. Just a thought on solar, the flexible are not up to par yet as wattage output is concerned. We’re waiting until leaving to add solar as each year they grow by leaps and bounds. Also, why are you wanting solar as you’ll need to run your genny often with the charter guests? Just for the off season when it’s just you two? Anyhow, love your blog and feel like I’ve known ya for years already!! Been there done all that with all your growing pains you’ve encountered along the way as far as fixing is concerned. I’ve never worked on a boat or anything really hands on before 3 years ago and can now fix just about anything, god I love/hate it!!

    • When on charter we will definitely be running the gen set so solar is less important. That is why we didn’t bother with it last year. having some solar will help to keep the batteries topped up during the daytime hours though, hopefully keeping up with the refrigeration draw. It would also be beneficial when leaving the boat for a period of time.

  4. We just installed 2 90W flexible Solbian panels with a Genesun MPPT controller per panel on our bimini. We’re on Georgian Bay for now. We’ve seen 12 amps coming in and replaced a 35ah deficit from morning to mid afternoon (with the fridge running and crappy old batteries that need replacing and are too small). On a cloudy day we tend to see 3-8A mid day and 6-12A on a sunny day. They’re usually putting out about 2A around 8am and they get up to high output by 10am.

    We’re stuck on the dock but we’ve disconnected the shore charger from the batteries (though laptops, etc are running on 120v from the dock).

    The attachment was pretty simple since we were having the bimini made new but refitting shouldn’t be difficult. They’re attached with Velcro above and below the edges of the panel, stitched on to the panels themselves (canvas guy was concerned about the little area available to sew into but it’s a fair soft material so it was no problem, much easier to see than dodger windows). We are planning to add some foam backing to stiffen them up a little because they have to go over one of our bimini poles but that might just be paranoia on our part.

    They’re light, they work, and unless you stand on the coamings you can barely tell that they’re there.

  5. It’s all about square feet Mike. The more square feet of solar panels the better. It may be that more, smaller wattage panels will allow you to cover more of those square feet. Also, any panel with a shadow on it (from the mast, a stay/shroud, etc) will be producing significantly less power. With more (smaller) panels, the total output of the system might not be affected as much by the inevitable shadows…

    s/v Eolian

  6. Count me in as another happy Solbian panel customer. I just have a single 125 watt panel that *zips* into the top of my bimini, with built in zippers from the factory but it does a nice job of keeping all the batteries topped off. Admittedly, if I had a refrigerator, and lived on the boat full time, I’d likely need three total, but they’re quite nice products. With a single panel in the sun, I’ll see up to 8-amps being returned to the batteries.

    I have rigid framed panels on the roof of my house, and while they work great there, I’m pleased I went with the more expensive Solbian thin film panels for my boat. Depending on the model you get, they can be as efficient as standard panels (@22.5%, with Sunpower cells). What I find useful is that they weigh only 6lbs each (so you have much less to worry about mounting structure), have zero metal to corrode in a marine environment (with exception of the electrical connection points), can be easily unzipped and stored in a blow, and strong enough to be stepped on all day long.

    While I have yet to prove it, evidence shows that thin-film style panels perform better in partial shading and during cloudy days.

    I’ve only had it for one season so far, but I’m quite pleased. The downside is that you certainly will pay a premium for a high efficiency & light weight panel like that. About 2x’s to 3x’s that of a standard rigid silicon panel: depending on options, $700 to $1,000 per 125-watt panel isn’t out of the question. I hope to save on the increased panel cost with saving from not having to engineer a stout mounting system, and through panel longevity due to its durability & materials.

  7. I was considering purchasing the Solbian panels but was a bit turned off by the price of about $800 each because I wanted to mount 4 of them on my mew custom bimini. Someone told me about another company that offers 100 watt flexible solar panels by the name of Renogy.
    Here is a link to their site
    I have heard great reports concerning thier performance and the best part is they are only about $200 each. So at 4 for the price of one I had to go for it.
    I purchased them but haven’t installed yet so I can’t report on performance yet personally.
    Hope this helps

  8. Since you sometimes charter to families with children, I would ask if the kids are likely to come in contact with the panels up on the bimini. If so, I’d recommend that durability should be one of your primary considerations.

  9. I’ve had friends with failed flexible panels; typically 2-3 years. I can’t imagine that charter use would be easier.

    The efficiency generally stinks, meaning 2x the area. In my case I didn’t want to use more area. They also run hot, since there is no air flow underneath.

    Certainly go for an MPPT controller with some extra capacity. Get one with an amp meter; help you see what is wrong.

    My hard top mounting was dead simple, only one hole (wire) required. Easy to take them off too. And I’ve dropped the boom on the frame numerous times!

    Big wire. remember, it is the difference between battery voltage and panel voltage that charges; any drop and you loose a LOT of that differential and a lot of amps.


    And while you are at it, consider where the power is going; saving with LED etc. can be cheaper than making power.

    Have fun!

  10. I went through similar thoughts to the ones you are now doing.

    I looked at the rigid panels and found that whilst they were definitely more powerful, their inconvenience made them highly undesirable. They are easily breakable, they are in the way unless you build an ugly structure at the stern, they tend to get hot underneath unless you can provide adequate clearance. They were also rendered much less efficient if they were shaded, eg by the boom. Depending on the type, this last point may no longer apply due to recent improvements in the connection of the cells.

    By comparison, the semi-flexible panels were easy to fit. You can walk on them, but make sure you pick the ones with the roughened surface! This means that you don’t lose the usefulness of the deck or bimini space. They are less efficient at midday but worked better in low light, so they start being useful earlier in the morning and longer into the evening. This more than made up for the lower midday power so long as you fitted MPPT controllers.

    I have read that it is desirable to fit separate MPPT controllers for each panel, or pair of panels if you have lots of them. This means that if a panel fails, or is covered with a towel or something, the others still do the job. Don’t let anyone sell you the old type of controllers as they do not maximise the useful output.

    Mine have been going for the last 5 years with no problems. None of the others that I know of have given trouble either. Good ones seem to be as reliable as the best rigid ones these days.

    Solbian has been recommended a lot recently. I have heard of the Aurinco ones but not seen any.

    I would echo the comments by ‘Coconuts’ and Christina above.

    The semi-flexibles are well worth the cost in my opinion.


  11. I’m in the same boat as you trying to figure out the best way to add solar to our Leopard 38. One interesting thing I found was a family friend added brackets behind the arch on their 38 and this allowed them to place the panels so they weren’t shaded by the boom. It also provides shade to the swim platform if that is desired. Can’t remember the exact configuration of your boat…but didn’t think the arch/swim platform was too much different than it’s little sister the 38

    My understanding is that the smallest amount of shade on a panel can render that entire panel ineffective (and depending on how it is wired, perhaps the entire solar array). Of course this is all research and not practical knowledge, but this came as a bit of a surprise when I started looking into all of this.

    Good luck…I know how confusing all this stuff is!


    • Actually the 4600s hardtop is quite a bit different that the older Leopards. It does not have that arch.

      • Oops…sorry…I think I was confusing your boat with a friends 4200 I was recently on. Since the traveler still runs across the hardtop, I’d guess that there is some structure up there so cantilevering panels along the back may still be a possibility…not sure how it would look though. And engineering something like that may be more cost than it is worth. Just thought it was a clever option to the usual method of partially covering the hardtop with panels where the boom would tend to shade panels.

        In our case we don’t, yet, have a hardtop. Looking at adding one to provide better access to the mainsail. So, I debate the location of mounting solar every day.

        Good luck with your design, I’m sure you’ll come up with a good solution.

  12. Hi Mike,

    I looked into the flexible panels from Solbian and Renogy when I was shopping for my solar setup and found that they are just the solar cell laminants that are used in making the rigid panels. Without the glass on top the surface they are way more fragile than a regular hard panel especially since the surface is quite soft (flexible), and they will get scratched and scuffed and this will reduce their output. Also I was concerned about their edges as I feel that eventually moisture will work its way in as it was designed to be sandwiched and sealed in a hard panel. It is corrosion and cracking that degrade most panels. I guess that is why they only come with a 2 year warranty. Most ridged panels come with 10-25 year warranty.

    I eventually went with the Sunpower 345w rigid panels and a Midnite MPPT charge controller. I had an aluminum structure made off the back of the hard top on my Leopard 43 that supports the panels as well as replaced the fiberglass davits. Very happy with the output here in the Caribbean, I get about 100 amps a day per panel into the batteries.

    If you are interested I can send you some pics and more info.



  13. I had a very bad experience with Solbian so I suggest to stay away from them.
    My panel have lost efficiency just after one year but they have refused to replace it.
    For the price I’ve paid I could have bought 4 panels of a different brand.

  14. Mike,
    Based on size and rated output, the Aurinco panels are more efficient (better quality) cells than most. I know Webb Chiles installed them on his boat and was very happy with the quality. He is currently circumnavigating for the 6th time now. His web site has some installation info.

  15. Hi guys,

    We added semi-flexible panels.
    I ordered them straight from china. With shipping the price was 1/10 of the cost in the UK.

    It’s the same panel before being rebranded.

    The service from the Chinese company was also better than most of the UK firms I spoke to as well.

    Been running them for five months now with no issues.


  16. Mike,
    Look in his Journal, that details the preparation of the boat. One example:

    Evidently Webb had an unpleasant passage to Somoa, 2 large waves knocked the boat over. His installation seems well prepared for bad weather.

    Question for Simon: how/where do you order direct?


  17. Just built a solar powered electric boat ( using 1500W-peak Solbian semi-flexible panels, let me know if you have any questions on them. They perform extremely well, better then rated. Used rigid panels on our Lagoon 400, but would never do that again.

  18. Mike,
    fyi, Webb is reporting at least 2 panels with corrosion on the output wire after arriving in Tonga. Not good, when you are in the middle of the pacific who cares about a warranty. I can get Powerup laminated panels for about a 1/3 of the price per watt of Aurinco’s, they require slightly more deck space which on my 27′ boat space is at a premium. decisions, decisions… Going to order 2 small ones and test them. I will epoxy the wire exit with G-20.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This site uses Akismet to reduce spam. Learn how your comment data is processed.