Flexible / Low-Profile Solar Panels?

[Paul Elliott]

I will probably be putting a hard dodger on VALIS, and in an effort to reduce the dodger height would like to replace the fairly typical 100W solar panels I currently have above the dodger (there are three panels) with low-profile units. Has anybody got a recommendation?

I'm looking at the panels from SunWare (SunWare), and their SW-3064 looks attractive. I could manage to fit nine of these 36-Watt panels in a 3x3 array on the dodger, in the space currently used by my 3x100W panels. The Watts/Area numbers look good, and they are flexible enough to let me mount them directly to the dodger. However, the USA distribution looks marginal, and the price is steep.

With a nine-panel array I would wire them all in parallel, and run them through my Blue Sky MPPT controller.

I consider this a long-term purchase, and am willing to pay a premium for performance and form-factor. Are there any other suppliers I should be looking at?

Yes, I am aware that the dodger is a poor place to put solar panels.

[CarlF]

I saw these folks at a boat show. The panels seemed well made also very light. I'm not sure if they are less flexible than Sunware. Pricing appears better (although still high) than Sunware. The grommets made it possible to just tie them down although there's also room to use screws.

Marine PV Panels, RV & Boat Solar Panels, Superwind Turbines and Charge Controllers

I'm interested in what you decide to do as I have a similar need.

Carl

[hellosailor]

Paul-
The output of solar panels drops as they heat up, so many are intentionally framed in a way that ensures there will be airflow under them, to keep them cool. Something to consider if you are trying to flush mount them or low mount them, and try to still accomodate.

[Paul Elliott]

Carl, thanks for the pointer. I'm going to be putting together a summary of all these solar panels, and will certainly share it here.

hellosailor, yes, you are certainly correct about the airlfow/heat issues. If I'm not mistaken, on most panels the frame is there to provide mechanical rigidity and useful mounting points, and while the ventilation is definitely a good thing, it is more of a by-product of the mechanical issues. I don't know if I will be able to get any solid data on the loss of performance due to heating when a flat panel is mounted to a fiberglass surface (compared to the free-air case), but I will be looking into it. Or at least I will try to find a rationalization for whatever my solution ends up being.

How about an aluminum dodger? Then the whole thing could be a heat-sink! I think I'm joking...

Here's another flat flexible panel: Modusolar le spécialiste du solaire sur mesure -- the site is in French though, which I don't read. They have these things on some of the minitransat boats, and I found a discussion here: Print Page - Ultra Thin (3mm) and very light solar panels Carbon-Kevlar based. The $$$/Watt number is quite steep.

-Paul

[hellosailor]

Paul, your aluminum dodger might just work. Fluted on the underside for better cooling, and made from titanium because aluminum is, after all, just so damned heavy. {G}

I don't know if you'd find specs on the heat caused by deck mounting, but any panel maker should have specs that show you the loss as the ambient temperature goes up. Then you take one of those IR thermometers, and see how hot your deck is (from the bare underside?) on a sunny day. Odds are...maybe it is 20 or 30? F higher than the air temp? Quick, call Mythbusters! :-)

[barnakiel]

Be aware thaere are two types of flexible panels - one type bends by maybe 3-5% and can be placed on slightly curved areas (like the cabin top). The other type is the true flexible stuff that you can roll. Be carefull if you buy the former type - I have seen one very unhappy owner not so long ago - he tried and failed to bend his over the recommended 5% and lost the thing.

The problem is that the real flexible thing is made from the less efficient silicone, so you pay a lot but do not get much. I would opt for rigid, quality mono or poly-crystaline things. They deliver.

b.

[senormechanico]

How about a dodger with integral water cooling? A March pump or similar drawing an amp or so might help the efficiency of the panels so much that they deliver MORE than an amp or so extra??? Or maybe with a large array, you could run refrigeration coils...

See what happens to my posts when I haven't had any wine tonight?

[Paul Elliott]

Quick report: I'm talking with Chris at IQ-Solar, and his stuff looks very interesting. It isn't flexible, but is low-profile. I found a few other possibilities, and I have a spec-summary and analysis on VALIS website: Solar Panels

As for a water-cooled dodger, I'm thinking that a Peltier-junction cooler might work well. In fact, it could possibly boost the panel efficiency so much, that the power generated would overdrive the Peltier cooler, and turn it into a superconductor. This would then of course create a perpetual-motion-style feedback loop, as long as I could keep knocking the icicles from the solar panels. At that point I might as well go with electric propulsion, or perhaps an ion-drive.

[hellosailor]

The IQSolar panels look interesting, but the only guarantee they have seems to be:
"IQSolar panels are the lightest panels on the market! Guaranteed. "

Where some companies like BP offer a 25-year warranty for marine use, while others won't warranty panels for marine use at all, or for much shorter times. The warranty, and the strength of the company behind it, are worth considering as well.

[jkleins]

I saw those at the boat show this year as well and am very interested. Not as much for the flexibility as the size/weight. We put ours out when we anchor so they have to store well. Those seem like a nice size to take in and out and don't have hard edges to bang stuff. Look forward to hearing your impressions if you get them.

Jim

[Paul Elliott]

Originally Posted by hellosailor

The IQSolar panels look interesting, but the only guarantee they have seems to be:
"IQSolar panels are the lightest panels on the market! Guaranteed. "

Where some companies like BP offer a 25-year warranty for marine use, while others won't warranty panels for marine use at all, or for much shorter times. The warranty, and the strength of the company behind it, are worth considering as well.

This is a good point, and with a company like IQ-Solar (IQSolar Home) or most of the others on my list (which are very small operations), I'm going to have to rely on their technical skill, and the fact that their customers (mostly racing sailors) subject the products to pretty brutal conditions. As for long-term reliability, or viability of the company, there I would be taking my chances.

With the big panel producers, much of their R&D goes into developing an efficient high-volume production process. Of course they do also invest in long-term reliability studies.

It's a bit of a challenge for me to accept that I'm considering paying about three times the "normal" price for a semi-custom solar panel. When I tell myself that this is perhaps a necessary part of a larger design it starts to make more sense. I've decided that I want something that I just can't achieve with an off-the-shelf high-volume product. If my budget were a big problem, I would definitely be more willing to compromise on my design goals.

One interesting feature of a system design using the 20-cell 82W IQ-Solar panels: The panel output voltage is much too low for most controllers (unless you have a 6V battery bank). The easy solution is to wire pairs of panels in series, but more intriguing method is to use per-panel "step-up" MPPT charge controllers made by Genasun (Genasun). This has some significant advantages in an environment with lots of shading issues (definitely the case in my dodger-top installation).

Genasun is another of those small specialized shops, but they seem to understand the environment (the owner is also an ocean racer).

[Paul Elliott]

Originally Posted by jkleins

I saw those at the boat show this year as well and am very interested. Not as much for the flexibility as the size/weight. We put ours out when we anchor so they have to store well. Those seem like a nice size to take in and out and don't have hard edges to bang stuff. Look forward to hearing your impressions if you get them.

Jim

Jim,
Chris at IQ-Solar tells me that he is about to introduce a very nice stanchion-mount bracket for his panels.

It may sound like it, but I'm not pimpin' for IQ-Solar. I'm still looking at other options, but their panels are the best fit I've seen so far. I have to say that I enjoy having my technical discussions with the owner. This is of course one reason why the price is high -- the large amount of customer interaction necessary in a semi-custom market.

[hellosailor]

Paul-
"Of course they do also invest in long-term reliability studies." More than "invest". A friend of mine once worked for a leading brand name consumer electronics company. His entire job? To predict failure rates and warrantee costs, because the company had to set aside budget to cover them every year. He had to generate accurate numbers for how many of each model would fail over time, how the warranty length could best be matched to the failure rate for best profits and sales, and while he was at it--to look at every competitor to see what they were doing and how they were doing it.
The kind of thing the public doesn't know: When Sony was clobbering the world with the new patented Trinitron color TVs, they tested each component once before assembly, each board once before assembly, and then a third test after each set was finished. Literally, 300% quality control. It made their sets damned expensive, but no one ever bought a Trinitron and took it home to find it DOA.
Then again, there were companies like Samsung (new at the time) where some folks took home two sets to find them DOA. 1/3 the price, but three trips to get one good set.
All gets reflected in the price. I root for the underdog rather than some of the greedy profiteers (like our cellular phone carriers) but sometimes, I want to know my purchase will be backed up with that warrantee.

Six volt panels ? What market are they targeted at??

[Paul Elliott]

Originally Posted by hellosailor

Paul-
"Of course they do also invest in long-term reliability studies." More than "invest". [...]

Believe me, I understand this, and I use the term "invest" in it's broadest sense. I've been deeply involved in the design and manufacture of high-reliability electronics systems for much of my professional life.

Six volt panels ? What market are they targeted at??

These work just fine in 12V and 24V systems, you just need a step-up MPPT controller. Or, you can string multiple modules in series.

I really like the concept of multiple smaller panels, each having their own controller. This greatly mitigates the partial-shading problems that we often see on our boats. I've sometimes pondered the practicality of integrating multiple step-up controllers on the back of a panel, with each controller being fed by just a few cells. But then I look at the low volumes, and the cost of an efficient low-voltage switcher, and realize this isn't really practical (but it would work really well!)

I've got friends who are in the home-solar market (Home - Enphase Energy), producing a very nice microinverter. The technical drivers, and volumes, for this market are in many ways diametrically opposite to the sailboat solar market.

Of course, if you have your solar panels on a stern arch you can avoid many of the shading issues.