Solar Power, Panels, Charging, Etc.`

[D. Fox]

I'm going to take the plunge into solar power shortly and need some advice. Aside from the panel, what other peripheral gear do I need to allow it to charge the batteries. Bear in mind my understanding of things electrical is fundamental at best. I currently have two batteries in the port cockpit locker that I've been charging with a portable charger. My energy needs are minimal - all I have right now is a VHF, bilge pump, running lights, and interior lights. I may add a couple other things (more lights, GPS, depth sounder, etc., but nothing major like refridgeration). I was thinking of getting a Siemens 10w kit from BoatUS that has mounts, a regulator and other stuff for about $150. They don't seem to be selling it now and it probably wasn't enough anyway. I just saw a Unisolar 32w panel at Sailnet for $199. I think that would provide plenty of charging power for what I have and expect to add, but if I go that route, what other things do I need to get to tie it all together.

(Steve, next time I see you at Whitehall I'd like to take a look at your setup)

Dan

[D. Fox]

Steve, you're getting at my question - what other stuff do I need besides the panel and what does it typically cost? I know I'll need mounts and cables. Do I need a regulator? What does it do, exactly? Prevents overcharging? Anything else?

Like I said, I can get a decent panel at a reasonable price at Sailnet right now. I'm just trying to understand what goes into the whole system and how it would add up. Thanks,

Dan

[commanderpete]

Or, how Commanderpete got his solar panel.

Wednesday night my friend and I were going out for a night sail. My friend is an excellent sailor and owns his own boat. I gave him the tiller as we motored out of the canal. Meanwhile, I got busy taking off the sail cover and getting ready to hoist the sails.

Somehow, my friend got distracted coiling a line or something. When I turned to look, we're heading straight for a piling about 15 feet away. Yikes! I slammed the tiller hard over.

Ever so slowly, the boat starts turning away as we approach the pole. (Now I know how the Captain of the Titanic felt). We give the pole a glancing blow and rubbed past it. Ugh.

I could barely stand to look at the hull. Now I have a smear of tar and cresote about 6-12 inches wide running along the hull for 6 or 8 feet. I had just painted the hull this Spring. Double Ugh.

We scrubbed the hull for a while, got most of it off, and went for a sail. My friend is really more upset than I am. I shrugged it off as best I could and told him to forget about it.

Yesterday he went down to the boat and finished cleaning the hull. He also left me a new flexible solar panel. I guess I had mentioned wanting one of those. What a guy!

The flexible panel is about two feet long. I think it will work as a "trickle" charger and I don't need a regulator. I'll have to read the instructions.

In the past, I used to take the battery off and charge it up at home whether it needed it or not. My outboard also charges the battery.

As for the hull, it looks good from a distance. I haven't mustered up the courage to give it a close inspection and see the scratches in my paint job. I'll deal with that next Spring I suppose.

Oh well. All's well that end well. It took a brush with disaster to bring me in to the modern world of solar energy.

I wonder what its gonna take before I install that depthsounder I bought?

[commanderpete]

Never thought that Steve would be a tree-hugging, sprout eating, save the whale type environmentalist and alternative power champion. Go figure.

Don't know if this scan will work, but here is some literature from my new Unisolar panel.

[commanderpete]

Yep, by owning a sailboat we're all reducing America's dependence on foreign oil. Gives me a warm and fuzzy feeling.

Hey Steve, you got a blender on that boat of yours? If I come down there you're going to need 50 amps just to make enough Margaritas.

Here is what Unisolar says about needing a regulator. Anything more than a 10 watt panel you're definitely going to need one.

[commanderpete]

DVD player..........hmmmmm.........next person that crashes my boat is gonna owe me one of those.

Then I can go below and watch "Captain Ron" while underway.

Sailboat's got the right of way, after all.

[commanderpete]

I understand that July 15 to August 15 is Summer in Maine (when the Black Flies fatten up).

The other 11 months is Winter.

[noeta-112]

Nope it's not winta yet - still black flies around - and the 3 seasons are - July, August & Winta.
I wrote a couple of pages about my season's sailing and went to post it and was prompted to log in ...:PO: Somehow I got bumped.

Will post again as time permits

rgds

[commanderpete]

If you run down the house batteries using the blender, you can always use this handy backup device

http://www.boatblender.com/

[Tony G]

Kent,

How about a run down on your solar panel and electrical system? What you have, what you like, what it does, where you got it, etc.. Being I don't have an inboard and, currently anyway, don't have an outboard with an alternator/charging system I'm looking at different ways of keeping 113 'electrically unhampered'.

Here's what I'm looking for-an electric start outboard with an alternator and has virtually no drag when we're sailing. Oh heck yeah, no prop walk either! And weighs 70 to 80lbs. while we're at it. And a big stack of $100 bills.

Tony G

[epiphany]

Tony G -

I've been looking at solar stuff too, being in a similar situation with an outboard that has no charging ability. I think that solar will be the main source of juice on #370 when she gets to that point. It will be nice to see what Kent has to say.

You might want to take 6 or 7 of your $100 bills and look at these 2 little 1kW generators - both 4-stroke, under 60dB sound, under 30# weight, load-sensing throttle (saves gas, lengthens run time), have AC and DC output, yadda yadda yadda. I'm thinking that they would make a good backup source for charging, as well as perhaps being able to run a small power tool (jigsaw, palm sander, drill, icemaker, blender). Well, OK, maybe the last two "tools" aren't, really, but one could dream... ;) The Yamaha seems to always be a little cheaper at the sites I've seen.

Honda (http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=eu1000i)

http://www.hondapowerequipment.com/images/model/eu1000-150.jpg

Yamaha (http://www.northwestpowertools.com/generators/yamaha/ef1000is.htm)

http://www.northwestpowertools.com/generators/yamaha/ef1000is.jpg

Also, one last thing - I stole your boat. Well, a picture of your boats interior, after you'd ripped almost all of it out. I'm using it to "draw" mockups of the interior layout for #370, sometime in the distant foggy future. Hope you don't mind. ;) :D

[Hull376]

Frank, you are oh so right about what it's like to peel away the last shreds of blue tape, stand back, and admire what one of these pieces of art looks like all shined up, looking brand new.

I'll post a new solar thread in the technical forum-- or maybe at the end of an old thread. I'll tell you how I figured out what to do with Charisma. I've got an excel spread sheet that helps figure out the right sizing of battery bank and solar panel based on where you live and what your loads are on the boat.

[Bill]

Steve Airing's post #5 at

http://www.pearsonariel.org/discussion/showthread.php?t=630

describes his solar panels . . .

[Tony G]

E, I like the generators. I once joked with Ebb about leaving the foredeck clean of LP bottles to make room for the genset.

Bill, I did the search for solar and panel. got some enjoyable, light reading.

Kent, That'd be great. Sounds like the kinda stuff I'm lloking for these days.

[Hull376]

At the request of some of the members, I'm providing my views on using a solar panel to run the electrical system on my Ariel. I've been using the system for about 18 months, and I'm happy to say that its works like a champ in Houston's latitude. My system is comprised of:

*one Kyocera KC-60 solar panel (60 watts) $250-$300
*one MorningStar SunSaver-6 solar panel controller battery charger--fully automated $50-$65
*10 GA wire and two panel brackets and rail mounts. http://www.e-marine-inc.com/
* two approx 100 Amp Hr Deep cycle marine batteries, lead acid type.

This system has been trouble free. I never think about power. I do check the fluid level in the batteries. The smart controller does a great job-- marinized in epoxy, senses temperature, optimizes the charging curve, can set to sealed gel or wet cell. I think maybe safer than shore power charger hooked up all the time???

I've never run out of power the way I cruise my boat, and have only used dock power when running my Cruseair airconditioner at the dock. Note in the attached spreadsheet that small loads from two fans run 24x7 adds up to some power, but with the solar panel charging, I don't worry about it at all. I don't use an inverter to run any AC appliances, I don't have refrigeration (ice works fine). To reduce loads, I would recommend replacing 15 watt incondescent cabin lights with the compact screw in florescent type-- more expensive, but way less draw.

Attached is a spreadsheet that I used to size my system, and to understand the impact of the various combinations of loads, battery size, and panel size. Its not perfect for every application, but it will give you a good idea of what you'd need to run your vessel. This will run on recent versions of excel. If needed, I can save it in an older file format. The intoduction worksheet will give you directions. Ignore the message that asks if you want to update links. The load sheet is filled in with one scenario I used for my boat-- you can change it as needed for your circumstances. Have fun!

[ebb]

Thank you Kent,
Don't forget some pics sometime.

Your attachment is unplugged, at least for me
as I can't get any image.

[Hull376]

ebb, its an excel file in zip format.

[ebb]

whatzat? I'll wait til favorite daught gets back. Thanks.

[epiphany]

I'll post them as images (800 pixels wide - is that OK? They were much larger, I rescaled them) from my site as I convert them, should have them all up in a few more minutes. Here are the first 2 pages. Thanks Kent!

Note: If you open them as a spreadsheet, you can put in your own figures etc and it would recalculate for you on the fly. If you don't have a spreadsheet application like M$ Office, you can get a free (no cost whatsoever) Office Suite at OpenOffice.org (http://www.openoffice.org/) . The English language download of OpenOffice for windows is about 66 megabytes.

http://com-pacowners.com/gallery2/albums/userpics/10003/screen1.jpg

http://com-pacowners.com/gallery2/albums/userpics/10003/screen2.jpg

[epiphany]

http://com-pacowners.com/gallery2/albums/userpics/10003/screen3.jpg

[epiphany]

http://com-pacowners.com/gallery2/albums/userpics/10003/screen4.jpg

[epiphany]

http://com-pacowners.com/gallery2/albums/userpics/10003/screen5.jpg

[epiphany]

This is the last one. These were opened using Open Office, I am not positive they look the same as they do in the m$ office program, but they should convey the gist of Kents calcs. Hope this helps!

http://com-pacowners.com/gallery2/albums/userpics/10003/screen6.jpg

[Hull376]

Epiph, Thanks. Now Ebb can have fun with the rest of us--- those with spreadsheets and "them" without! All look fine, except the last graph which is funky looking but not of much importance anyway!

[willie]

You guys are awesome. That's some of the most useful info. i've seen here.
Now i have something else to ponder upon the rest of the winter!
Thanks!!! :cool:

[Robert Lemasters]

I just read were some scientists from Canada have just made an important breakthrough in solar electric generation. A more powerful solar panel, 30% more elecrical power and get this. It is so thin strong and flexible that it can be applied to canvas. Could generate enough electrical power to operate an electric motor for propulsion, even works in dim light. According to what I have read product should be available in next two or three years. Also it seems that this product is a single film that may even be spayed on. Imagine your sails as large solar electrical generators providing electrical power in addition to wind power.:eek:

[Hull376]

ebb and Tony G wanted a few pictures. Really not much to show-- a panel, some wires, and the controller! Say Robert, can the Canadians spray some of that stuff on clothing? I wouldn't need chargers for my iPod or cell phone anymore-- just plug into a zipper or button hole! I might look like some kind of space alien on an old Star Trek re-run though!

[Hull376]

Another pic

[Hull376]

The controller. It is a pretty sophistocated (sp) piece of equipment. It uses pulse charging and a special charging algorithm that causes the battery to take a full charge. The manufacturer says that tests show it will bring back a fairly worn out battery and punch through crystalization in the cells.

[commanderpete]

I'm trying to figure out if its worthwhile to buy a Gel or AGM battery. They cost twice as much as a regular battery.

Seems like capacity is about the same. They have a lower self-discharge rate, which is good. Otherwise, I don't see the benefit.

[eric (deceased)]

in the above picture where the solar panel hooks in ....looks like the polarity is reversed...the white wire should be connected to + and the black to - or is there something not shown...also is there a diode somewhere between the solar panel and the unit itself...

[tha3rdman]

Eric,

I admitidly dont know much about DC wiring but you typical household wiring bare and White is neutral the black and red are hot, which look like that was the format he was following.

Aside from that second black, hell as long as he knows where they are going.

[ebb]

Check out the Odyssey 'Military Grade' AGM batteries. Gels are too finiky. Maybe cranky's the word. And wes maroon won't have them.
Made with virgin lead, Huge service life, same battery for starting and deep cycle, 10 year service life, chargem with your old wet battery charger. 22 page 'technical guide' worth looking for on the site. No prices!
www.odysseysoutheast.com

[tha3rdman]

Prices of Oydessy Batteries from a delaer here in MD
http://www.1stopmarineshop.com/Products.html

PC 680T
$145.95

PC 925T
$153.95

PC 1200T
$187.95

PC 1700T
$253.95

PC 2150MJ
$317.95

[ebb]

3rdman, those prices seem comparable ("compeditive").

Be great if a comparison chart existed that cut thru the hype and maybe cut open the batteries to show us what we paying for. Generally an agm and gel are going to last longer and cause less grief than a wet cell. I'd like to see these high end batteries put to the test (against their claims). How would you test 'service life'? Cycling from 100% discharge 'over 400 times' to 100% capacity certainly could be designed into the procedure. Charging in 1/3 of the time it takes for wet cells, is another claim that could be tested. I guess you could drop then a few times as well.

Odyssey's 'drycell' means just that, there is no acid to spill out of a cracked case.
Agms are more vibration resistant than gels because of the way they are made.
Agms are more efficient charging than gels, have a higher charge acceptance, and while some gels claim to have a long life, agms are said to have a reasonably long life. Go figure.
Agms and gelled are sealed. They require internal pressure to work properly. It's possible to pop a safety valve, which is why it is best when going for these batteries to upgrade to a sophisticated 3 stage charging controller. ($)
It means tho, to me, that you can place these babies in an enclosed living space, which I would not do with a wetcell.
Out side of that, what are the differences between agms and gell?
Length of warranty has to be a good indicator of craftsmanship.

[ebb]

Solar panels keep advancing.
Look at the (bimini grade) 20W roll up 'Powerfilm' (15.4 @1.2A) for $320 on
www.siliconsolar.com

Scroll to Marine Solar Panels

Be interested in what you think since ayeno diddly about this stuff.

[tha3rdman]

ebb, On that site it also hase where you can buy Solar cells 2nds, for 1.60 a watt.

Granted they are ridid cells but has any one every soldered their own panel? How involved is it?

Figured it would leave you the flexibility to make a custom panel to fit where you wanted to put it.

http://www.plastecs.com/solar%20cells.htm - also sells individual cells wish they would break out the watt/sq. in.

[tha3rdman]

Has anyone considered using solar powered spotlights as spreader lights, As I see it the only disadvantage is not being able to turn them off.

[Tony G]

Not bad, this thread goes back 3+ years. It must be time to resurect it.:D

On one of the other, more recent threads Kent gave us a limited update on his system. Everything works great. So to that extent I did a little digging around (read shopping). Many forums on the web give the Kyocera panels a thumbs up. But the 50 watters are getting hard to find. It seems most of the places I looked were out of stock and some didn't anticipate seeing more any time soon. There were a few 65w, and 80+watt are dreadily available. But the price from a 50 to 65 watt nearly doubles. Did I ever mention that I'm a cheap date-er-skate.

There was a service tech ready to talk this afternoon, maybe milking the Friday timeclock, that seemed knowledgable enough. Found me some 50watters of the same quality, construction, and, in his opinion better track record, albeit somewhat bigger. He proceeded to tell me some of the commonplace 'alterations' customers make to toughen the panels a little more. Of course he didn't suggest I do anything like that even though the manufacturer doesn't warranty their panels for a marine enviornment. Nudge, nudge, wink, wink.

So with Kent's product approval head-nod we blew nextweek's paycheck on a sunsaver controller and a couple of 50 watt panels. Now, I'm not planing on a TV aboard like Aussie Geoff, just enough power is needed to power up a lap-top, or lab-top Craig;), stereo, and electric accordian with full compliment of effects pedals. This boat be rockin!

[ebb]

Thinfilm solar was invented 30 years ago -
yet already available for barn roofs true peel and stick inkjet printed solar film has not arrived in our niche market.

The oil and silicon crunch hopefully will put some wings on this technology.
I don't bet on it, being a cynic.
Solar energy seems to attract the most conservative research and development and product imagination in the western world. Its almost as if they are more interested in piggybacking into silicon markets than perfecting the technology. Even the acronym CIGS (for copper-indium-gallium-selenide) has a negative addictive quality.

The time is overdue for pasting featherweight energy making films on hatches and windows. We'll be sticking semi-conductors on mast and boom, on the dodger and on the cabin top.
There'll be simple connectors, direct sun won't be needed for fully charging our AGM's, and there are MBA's right now figuring out how much to stick us for it.
__________________________________________________ _______________________________________________
Paper thin (probably more like cardboard thick) roll up silicon panels are available now. Powerfilm (IOWA SOLAR) is one product. They buiild their panels on plastic rather than glass. Silicon is considered clean, using no highly toxic cadmium that other thin film panels use. The silicon shortage has ended, and while it may get cheaper for manufacturers, it's unlikely that panels will get cheaper for us. Silicon costs more to manufacture into panels and is 1/2 as efficient as CIGS in converting sun to electricity. Little ships need efficient sun energy converters - in ounces not pounds.
__________________________________________________ ________________________________________________
However you will still find Don Casey saying that thin film (rigid or bendy) are 1/2 as efficient as crystaline silicon. While crystaline panels themselves are only 10% efficient at collecting energy and converting it to juice. Warrenties for crystaline panels run 20yrs. Thin film 2 to 5 years. But we may be entering a new age where high oil will push solar to the forefront and innovation will become rapid. And hopefully cheaper.

OZsolar out of Sweden has 25W thin (3mm) film panels you can apply directly to the deck or hull(!). Sizes are 27.2" X 13.6" and 52.8" X 7.2" and 24" X 17".
All 25W and if my conversion is correct 490grams = 16 ounces each. So change is happening. What's the warranty (life expectancy) on these? Are they CIGS or silicon. I can see a solar bra on Little Gull's cabin nose like a Porsche! These seem like handy sizes. And imco as Ariel Cruisers planning our electrical needs we have to start at a minimalist 100 Watt level ( in terms of solar collector surface area) and par it down from there if we have to....

Won't be long we'll have solar panels we can tie onto the lifelines with the lifetime of sunbrella.
Or how about sails being solar collectors?
"Honey, unfurl the small jib we need to charge the Engel!"

[ebb]

I'm challenged by electrics. Don't have the knack for it.
In roaming around the net looking for info - or really looking for how one person did it on their boat - I've often been disappointed. Or 'put off.' General and basic info is useless - the only way I can learn is by example - so going to manuals and books for me is not an option.

The only way to learn is to jump in and acquire the basic stuff by example and necessity. Most controllers of info think you have to start at the beginning. Their tutorials are based on classic education models which are deadly and boring.

The teacher however has to be truly gifted - that's the problem - there aren't too many of them. I have not found a single book on electrics that uses a creative hands-on method to inform the reader on how to wire a 30' foot boat, let's say, from scratch. Of course there'd be a start at a beginning, like learning to sail, basic basics, but then: 'Bam!' here's some ways of setting up your distribution panel, etc. etc. With the whys and wherefores sidebarred and referenced.

Anyway, It is probably a testosterone allocation problem that can't be dealt with here.

We boat people are an RV by definition,
http://www.wind-sun.com/ForumVB/index.php
Set up like Bill's here, there is a nice familiarity, with tons of stuff to wade through and personalities, some seeming well informed.....and there is for newie's a PV Beginners Corner.:confused:

[if you go to the url above and get the intro page.
go to the PV Beginners Corner.
go to pg 2 and find an entry by 'techomadia' / 'Solar recommendatiions for a tiny RV....'
Read that entry, naturally, and check out
"Details and pictures of new project archived here."
There is a blue bar that is unresponsive off that page.
But the connection with we who are redesigning the A/C interior and yearning for long passages is obvious: minimalist nomad necessity, gear, construction of their new glass trailer , and solar. Meet somebody new, a couple into tiny living spaces - nice bright blog.]

There are boat specific discussions and prognostications by self-ceded shoguns and gurus on the Advanced Solar Electric Forum.


We have to deal with electrical energy from the minimalist stand. Most posters talk as if they have a huge house platform and addictive needs. It's doubtful that an Ariel can carry a Honda generator and an Ampair wind turbine Yet depending on only the sun for charging batteries out in the South Pacific seems rather foolish. Small boats can't take much hardware weight.
Some people want to get away from it all.
How much is too much - how minimalist becomes too uncomfortable to be fun and sustainable???

[Tony G]

Ebb

I hear ya, man. I am by no way an EE. Not even a rank novice and for over a month now I've been reading about panels and regulators and controllers and flooded and gels and three stage and four stage and hydros and wind and blah-blah-blah! There seems to be much discussion out there regarding the topic. And every time some one says 'I did this.' some one else sez, 'oh, you would have been better off doing this instead.' The manuals seem to be, largely, nuts and bolts. Put tab A in slot B.

I'm just going for the basic, minimal system. No desire to be the best set-up out there. Nav lights and radio are my main concern. The refer doesn't have to be full time. It would be ideal given the amount of money, weight and space given up for it. Interior lighting will be some LEDs and a lamp or two maybe one of them cold somthin flourescents.

A bigger boat and it would be okay to 'have it all'. Sure, you have to continually fix things because they're breaking down, but, come on-fixing a refer on your own boat in a nice little bay somewhere warm...I'd do it. A self-realized workaholic and yet a lazy-@$$ I think that would be the perfect retirement for me. It'll all get done when it gets done. Relax mon, everything is gonna be all right! Adapt and make the best of what you have. Look on the bright side and stuff like that. Or my all time favorite, People don't stop playing because they get old. They get old because they stop playing.

[ebb]

But I want my 'lectric blankie!:o


And computer, electric anchor winch, pumps, fans, radios, phones, fridge/icemaker, lights, actuators, inverters, water-heater, water-maker, GPS, LORAN, stereo system, depth sounder, electric start on the Yamaha. What I miss... the charge controller.

Look into the PWM, pulse width modulator, Morningstar Sunsaver SS-10L.
Desulfates your batteries, increases battery charge acceptance, reduces heating, self regulates for solar panel anomalies. and more promises. Ultimate jeeves for your deep cyclers.

Going off grid is the ultimate,
But on the Ariel it's like expecting to live off a windowbox veggie garden in the city.

[Tony G]

Ooh! Forgot about the fans. How about a recumbant style stationary bike with a generator hooked up on the foredeck? A guy's gotta stay in shape out there. We did buy the complete nav/boat toy kit, but I'm hoping to only use instruments to verify sail trim until I know what the boat likes and maybe check depth on the go. Lap-top is probably going to be-necessary(?). You're exactly right with windowbox analogy!

I figured I'd just spot all the Morris and Hinckleys in the bay and then go 'glob' off of them.:D Just kidding.

Didn't want to pay the extra $8 for the low-limit cut off so we stuck with the SS-10.

[c_amos]

Looks like a good set up Tony.

FWIW, We started our trip with a 40w panel, and found that was lacking for our engle fridge. I added 2 25w Sunlinq flexible panels which fit perfectly on top of the dodger.

I was sadly disappointed by these Sunlinq brand panels. I see West Marine has now picked them up.... I can not say enough about how poor their output was. I tried several locations, and never got more then a couple hundred ma out of either of them (or both). Fortunately I was able to return them to the hippie alt-energy place I bought them from (~750 for the pair).

Next trip we plan to have a ~120w panel over the top of the pushpit. If not for the fridge, we would probably be happy with the 40w panel we started with.

As a matter of fact, I was at the boat a couple hours ago. I have a link 10 battery monitor that keeps track of all the amp-hours that go into and come out of the battery bank. It has not moved from %100 since we turned off the fridge.

[Tony G]

Craig

That real world experience is what I'm looking for. So are you going to have a 120w and a 40w on Faith? Now I'm just being stupid...

This may be stretching this thread a bit too far but do you think your Engel's performance is in line with that of other owners? Was it a matter of loading less than cold items into it or going into the unit frequently such that it was continually catching up? Will adding more insulation, in your opinion, around the refer help?

If there is another, more appropriate thread out there for your answere, please redirect me. Or you could pm me also if you have some info for me. Thanks

[c_amos]

I don't think we have an Engle thread here. There is one on SailFar (http://sailfar.net/forum/index.php?topic=738.0), but my impressions of the Engle (model 27) were favorable.

The mgf lists the current use as .7a That is based on a 24 hour day at a given ambient temp. It uses 2.4a when it is running, and it does not matter if it is in refrigerator or freezer mode. The difference is all in how much of the time it runs.

We only used ours for some cold water, and a couple of food items we might have done without. When it was cooler, it ran very little. When it was hot out, it ran much more often. Using the Link 10, I would estimate it averages 30ah a day... not bad by refer standards.


That real world experience is what I'm looking for. So are you going to have a 120w and a 40w on Faith? Now I'm just being stupid... No, I would just replace the current panel with a 120 or 130w panel. If I were doing without the fridge, or only doing weekeends I bet the 40w panel would be fine.

I looked for a picture of the way the panel was mounted, here is the best I could do;

http://sailfar.net/gallery/albums/userpics/10014/normal_Trip_10_0363.JPG

Also, FWIW, I had the panel(s) running through a NC25a flexcharge controller. I did try the sunlinq panels without it, and found it made no difference (the Sunlinq really are junk IMHO). The controller was added more for the output of my outboard, since it lacks a regulator.... but it seems to cause no appreciable loss.