solar power for my new toy

Skyko · March 2010

I am getting a (~3hp equivalent) electric outboard for my 17 foot sailboat. This is Torqeedo's (a german company) new 1003 model which is totally sealed (and submersible, but lets not do that) and uses a very efficient brushless motor and 400 watt LiMn battery (which sits on top of the motor much like a regular outboard gastank). They also market a 62 watt CIGS solar panel which they say can directly run the 1003 on the lowest power setting, pushing a 1.5 ton boat at 1.5 to 2 knots or it can be used to charge the onboard 400 watt battery. I don't think there is really anything special about their foldable CIGS panel except that it produces 40V open circuit instead of the usual ~20V.

Anyway, I was thinking about how cool it would be to have around 200 watts of solar on my sailboat so I could putter around at 2 or 3 knots on becalmed but sunny days (we get a lot of those in the summer in the puget sound). The problem is there is not a lot of room on a 17 foot sailboat for 200 watts of permantly mounted panels so I am curious if you guys have heard of anyone who has made a solar sail or something that I could raise up the halyard and keep pointed at the sun (sort of like solar tacking, heh heh). I guess I could string together a number of Powerfilm or Brunton panels and attach them to a webbing, but perhaps there is a better product? Would it be unrealistic to purchase some of the evergreen cells on ebay that are under $2 a watt and try to fashion some sort of sail?

BB. · March 2010

Re: solar power for my new toy

Imagine how to make sails out of 1/8" single strength window glass tied together with lengths of extension cord...

Next, imagine how to make sails of out silicon cells that so thin you need to float the stack apart in warm water to prevent cell breakage...

About the best you can do is hang the panel(s) off the stern (temp or hard mounted)... You could do "silly things" like using your tender (if you have one) to hold the panel(s) and tow it off the stern to get the panels away from the your sails and lines (any shading on a solar PV panel really can kill output.

-Bill

Skyko · March 2010

Re: solar power for my new toy

Ya, it is probably not realistic to try and build anything from scratch nowadays. The powerfilm marine grade rollable panels (I have a 14 watt model) do not have the shading issues (I guess because they are thin film type). If they are 50% shaded they just drop the power by 50%...in other words the shaded portion does not consume the energy of the nonshaded cells (I haven't scientifically tested this a lot yet though). I can get the rather long 28 watt version for around $300 and four of those would easily fit in the area of my mainsail. $1200 for a bit over 100 watts is a bit expensive though, and I could probably only go just over 2 knots in full sun (which is better than just sitting dead in the water I guess).

Perhaps there is space for 80 to 100 watts of those 21% efficient monocrystaline cells...is anyone making a marine grade panel out of those nowadays?

BB. · March 2010

Re: solar power for my new toy

The shading is dependent on the cell layouts too... One axis, you probably get a 50% reduction--as all the series connected cells are equally shaded.

If the other axis--you may get 1/2 the series cells fully shaded, which will drop the panel voltage (by ~1/2 volt per shaded cell)... Which, if Vmp is low enough, will kill the output (panel voltage is less than battery voltage--cells go high resistance, there may be bypass diodes, etc.).

-Bill

Photowhit · March 2010

Re: solar power for my new toy

Not sure what type of sailboat you have, or what type of sailer you are...

...but if you have a day sailer with a take down mast, I could see setting up a pair of effiecent 100-130 watt panels to mount above the mast, if you have a carrier mount for your mast. I'd go with 2 smaller panels incase you need to pull them quickly, 200+ watt panels are pretty big.

Even with a setup like this, you would need to be a strong sailer, to mount the mast if a storm blew up, or better keep a battery for such an emergency, to run home.

My last sail boat was a 19' Alacrity with 3 berths and a fixxed head... only thing I miss about living in Florida...

Skyko · March 2010

Re: solar power for my new toy

We started sailing in the Puget Sound area about 6 years ago and got our little 2005 Montgomery 17 in 2007. She is a sturdy little boat with a 600 pound fixed lead keel and can do about 6 knots close hauled with good wind. I have a 2.5Hp Yamaha that we mostly only use for 10 or 20 minutes during launch and retrieval (it is a trailerable sailboat). I originally had the idea of getting a Minn Kota Riptide trolling motor as a backup in case the 2.5 Hp had issues on a windless day and we needed to get back to port but the largest 12V model I could get was a 55 pound thrust and it would require some heavy wiring to deliver the 45 amps from the battery (and a circuit breaker, more holes in the boat for connectors, etc.). When I saw the Torqeedo with its built in battery (no heavy wires and I^2R losses) and almost double thrust for not too much more money I decided to go for it. Probably the 400 watt battery will suffice for most trips and I already have plans to incorporate a Vicor 10-20V input 30V output DC-DC converter module to allow charging of the 400 watt LiMn battery from my onboard deep cycle lead acid battery through the 12V lighter accessory outlet I installed last year near the tiller. IIRC I used around 12 guage wiring for it and have it hooked up via a 15 amp breaker so it should be able to put at least 100 watts/hr back into the Torqeedo battery in an extreme emergency. The solar panel idea was just me wanting some coolness factor and wanting to experiment.

Here are some pictures of the boat (and about 15 other Montgomery 17 boats) from last year when we invaded the US and Canada San Juan Islands for two weeks. My boat is the one named Eidolon that you can see in the sling launch in the 7th or 8th picture.

http://www.eidolonyacht.com/sanjuanislands2009

Photowhit · March 2010

Re: solar power for my new toy

Very nice boat, Looks to have a usable cabin!

Skyko · March 2010

Re: solar power for my new toy

I call it our Tardis. It has a 7 foot long v-berth (I am 6'7") and two quarter berths that are more like coffins that we use for storage. No fixed head but room for a wag bag type porta potty. We have stayed in it for a week at a time.

I read a few other posts and didn't realize how cheap something like a Koycera 135 watt polycrystalline panel is (like $400). If I could manage some sort of removable mount for that off the transom I could probably cruise at low speed off solar alone (or keep all of my electronics going while on a trip to Princess Louisa)

westbranch · March 2010

Re: solar power for my new toy

Don't count on sun too much in Desolation Sound for charging unless you have a 'point-able' panel or array, you would have to reset it on each tack. Especially in Pr. Louisa arm

Plus you would need it at at least a 45 degree slope to max out the PV output.

Neat idea though.

Eric

Skyko · March 2010

Re: solar power for my new toy

Ya, I haven't had the chance to make the Pr. Louisa run yet but I hear it is one of the most beautiful sails in this region.

What would REALLY be cool is if the Torqeedo was able to operate in generator mode so that when you were on a really strong run you could recharge it's battery or even the main electronics boat battery. Really seems like it should be possible since they use a really nice brushless motor in an outrunner configuration with rare earth magnets. Maybe when the warranty runs out I can hack in a three phase rectifier and some electronics

Or I could build a towable generator....don't have any experience with those though.

tabbycat · April 2010

Re: solar power for my new toy

You may have bought the wrong Torqeedo model. I own a Torqeedo 801L with both the lithium battery and a battery adapter which I use on a 25' sailboat. The adapter lets me use two Group 27 batteries in series for 24 volts. I can easily travel ten miles at three knots in calm weather and still have battery capacity left.
I have a 50 watt solar panel on board which recharges the Group 27's. It takes about a week to recharge them with a small panel but I don't use the boat more than once a week anyways. Thanks. Steve S.

Skyko · April 2010

Re: solar power for my new toy

The information I have says the Torqeedo 1003 is just an improved version of the 801L that does not fold up (which could be a disadvantage for some). It will still allow you to operate it off of external batteries and it has a solar charging port on the built in battery as well. It has about 20% more thrust and 30% more battery than the 801L, and supposedly is quieter and totally waterproof.

That being said, the 801L is on clearance at West Marine for $1400, so is a bit cheaper. I think they are really planning on people buying the 1003 in the future.

I plan on using a 175W to 230W solar panel, so should be recharging much faster (with an obviously much larger and more expensive panel to deal with).

Glad to hear that the 801L pushes your 25 footer so well. My 17 foot should have no problems.

niel · April 2010

Re: solar power for my new toy

am i missing something here as a 3hp motor is well over 2kw? now he does say equivalent, whatever that turns out to mean.

Skyko · April 2010

Re: solar power for my new toy

It is very hard to relate hp to boat speed or to relate gas outboard hp to electric hp needed for the same speed.

The gas outboard is horribly inefficient at lower speeds, mostly due to the high rpm small prop I believe. Closer and closer to the hull speed when the outboard is actually doing 3hp, then I believe it is better.

The torqeedo uses a 1000 watt brushless outrunner motor geared down with a planetary reduction turning a quite large prop which has been specifically designed to operate in this range.

I too am a bit unsure if they are saying the 1000 watt Torqeedo actually performs as well as a 3hp outboard over the entire speed range, but I don't really care too much, as the 2.5hp gas outboard I currently use is rarely run at more than 1/2 throttle.

solar power for my new toy

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