Hanging Solar Panels - with a winter cover?

[Taylor]

My boat is stored on a bouy. I just bought her in November, and I've now realized that I did not factor in the rapid self-discharge rate of deep cycle batteries into my plans to use a bouy. I've only been able to get up to the boat about every three to four weeks this winter to run the engine, and one of my two battery banks is suffering from pretty deep discharge, and I'm pretty sure the other bank is mad at me too. So I've got to mount a solar panel. Calculations show that I need a big 64 watt panel, and these things are large - about 50"x30"My boat has a full winter cover, and this is doing a great job of keeping her looking young. But it makes mounting solar panels tough. The cover goes over all the rails and halfway down the side of the boat all the way around. I'm thinking of hoising the solar panel in the foretriangle with a jib halyard using bridle and then securing it down to whatever I can find (like stays and shrouds) that stick above the cover. Has anyone tried this, and do you have any thoughts or advice? Are there any good alternatives?Thanks, -Taylor

 

[Ross]

A panel that big will fly around like a kite

when the wind starts to blow. Also you need to be sure that it will always "see" the sun while the boat moves around the mooring. Would a wind generator serve better? If the batteries are self discharging that quickly their best days are probably behind them. My AGM batteries don't lose a 1/2 volt over a five month storage period when they are less than 3 years old. after that they don't do so well and in about the fifth year I can expect to replace them.

 

[Night Sailor]

Clamp it

Put flexible 64watt panel over boom. Use lines going from panel to padded cabinet or C clamps fixed to hand rails, stanchions, rub rails or waht is available over the existing cover, clamping down cover as well.If panel is not flexible, then make a cradle of line between mast and shrouds. Lay panel on cradle and fasten with hardware or line. A good solar panel with still trickle charge with 4 inches of snow on top. The key is to have the batteries fuly charged before the solar panel has to maintain them. Remember that solar panels vary in output relative to amount of sunlight, temperature and angle of absorption. Your batteries are going to change their charging characteristics based on type, temperature and age. 64 watts isn't much for a winter time trickle charge on a large bank. I"d get something larger, like a 120 watt paenl (effectively about 7 amps in ideal conditions)I've been using Optima AGM batteries in all boats, vehicles and Rvs for 10 years. One is 8 year old backup, and drops only 2 volts after 12 months on the shelf. If charged correctly, Optima AGMs will not lose a full charge with only a 11 watt panel doing it's job. That's what I have in my boat keeping three Optimas going. I never have to worry about the state of charge when I go down to the dock.For future cruising plans I will upgrade to a single 120 watt Kyocera panel. I'm currently designing a dedicated arch for the panel and all antennas on the stern. In my RV I use two 120 watt Kyocera multicrystaline panels and they satisfy all of the demands I make from my three Optima marine deep cylce 55 amp batteries. Any time of year.Hope this helps.

 

[Taylor]

Yes, but...

Yes, but... apparently flexible panels are no longer available, at least those from Uni-solar. Flexible was clearly the easiest way to do this, I could just put some grommets in the cover and unroll it down the length of the boom. Does anyone know a current source for flexible panels? It would solve a lot of problems for me.Ross- standard deep cycle batteries discharge at 1% per day, (I have four Trojan 105's and a pair of 8D's) thus if 30 days stretches to 45 then I have batteries that are way down, and I'm shortening my battery life. So yes, you're right, one of my banks (the 8D's) looks like it may be at the end of life, but whatever I do in terms of replacing it, I need to provide some sort of float charge to get from 85% (where my alternator is going to leave the bats on anything besides a day long run) and get them to 100%. Certainly when I go to replace I'm going to make one bank into a starting bank (which self discharge at a lower rate) and the other bank will be upgraded to whatever has the lowest self discharge rate in a deep cycle, which may well be an AMG. I thought about wind power, but that's a bunch more money (minimum $1 kilobuck) against a possible $3-400 for a solar panel. But the key to long battery life (and convenience) is to keep the float charging, and solar is the easiest way to do that. I just need to put the darn thing somewhere.

 

[Capt. Chuck]

Take them home

Take the batteries home and periodically charge them with a car type charger for the winter. I have done it for years and my last set of batteries lasted for over seven years. They were still good when I replaced them.

 

[Rich Stidger]

Taylor, I think your best bet is....

to do as Capt Chuck suggests- take the batteries home and keep them charged. The T105's are only about 66-70# and can be moved off without huge difficulties. You will need another person to help you do the transfer to a launch or dinghy.Regarding the 8D's- unless you are a LOT bigger and stronger than me, these are basically put in place until replacement time. If you think these are near EOL, simply leave them and replace them in the spring with something that is much easier to handle. Maybe two T105's for each 8D?For the cost of the solar panel you can buy new batteries and then maintain them properly over future winters.

 

[sailexa]

For what it's worth........

I leave a 75w panel tied to the cabin top UNDER the white tarp (that woven plastic stuff). Stills puts out 4A in bright sunlight. It keeps 2 T105's comfy all winter. I run the panel through a charge controller however - if connected straight I find it will eventually boil the batteries. Are you sure everything is off? Almost sounds like there's some trickle load going on? Cheers.

 

[Rick Sylvester]

A couple thoughts

Here's a link to the folks I've done business with for my panels. John and Libby are sole proprieters at SVHotwire and know their stuff.If you're talking about monocrystal or polycrystal panels I'm happy to report that you're about twice too big for the size you mention. You can get a Kyocera 65 that's about 30" x 26". IMHO 65 watts is plenty for a trickle charger and as sailexa says, for unmonitored use a regulator is a VERY good idea.As others have said, putting a big panel in the rigging is a bad idea. It would be no trick to clamp it onto a pushpit where it would be far more secure, produce less windage and still be easily removeable.You know, if you're going to go this far, why not spend a little more for some real capacity and mount them so that they stay on when you're actually using the boat? Having lived with ours (two Shell 110's) for a year now I can tell you it's a wonderful thing to be making power in complete silence while our friends are listening to their diesels.

 

[John]

70 watt solar pannel

I have a C30 and have a k 70watt pannal mounted on 1"SS bimine tube with bimine hard where it is run up from the rear polepit and sits above the bimine behind the backstay .I leave it on winter and summer .In the winter i cover the boat with a tarp and leave the solar pannal up .works great winter and summer.the poles are bent into shape with a elec conduet bender I used a 11/4" bender with the 1" pipe I had one in the truck.Ihave a blue tarp on coustom made wood frames I can stand on the cockpit seets The suns UVs will shine thru some tarps and you could leav the pannel on the seet in the cockpit I have solar vents under the tarp that work all winter. This year i have a vent system hooked up to a 32watt flex pannel that runs all day and nidht John

 

[John]

70 watt solar pannel

I have a C30 and have a k 70watt pannal mounted on 1"SS bimine tube with bimine hard where it is run up from the rear polepit and sits above the bimine behind the backstay .I leave it on winter and summer .In the winter i cover the boat with a tarp and leave the solar pannal up .works great winter and summer.the poles are bent into shape with a elec conduet bender I used a 11/4" bender with the 1" pipe I had one in the truck.Ihave a blue tarp on coustom made wood frames I can stand on the cockpit seets The suns UVs will shine thru some tarps and you could leav the pannel on the seet in the cockpit I have solar vents under the tarp that work all winter. This year i have a vent system hooked up to a 32watt flex pannel that runs all day and nidht John

 

[AndyK]

I wouldn't take them home...

You still need batteries to run the bilge pump, otherwise you could be in real trouble. Remember, he's on a mooring.

 

[AndyK]

I wouldn't take them home...

You still need batteries to run the bilge pump, otherwise you could be in real trouble. Remember, he's on a mooring.

 

[Taylor]

Those are some great ideas

These answers have really helped me. Rick - the SVHotwire site was very interesting. As I looked it over and read their recommendations (particularly the part about mounting above davits in the stern) I realized that I have a hefty wrap around stern rail and a couple of places where the winter cover is slit to accommodate the backstay and a loran antenna that I could use to get a rail mount for a solar panel attached that hangs over the reverse transom.John - I have never tried bending SS tubing with a EMT bender, I always figgured it would be too hard, but the ability to bend tube around a boat is always a good idea. All I have is a small one for 1/2" EMT. But I have some 7/8" stainless tubing left over from a project on my Whaler, so I'll look at a tubing bender for that and see what I can do. Any advice on bending? Do you fill with sand or anything like that?Sailexa - I *think* everything is off, I have the battery switch set to off when I leave the boat. The ammeter reads zero, but its analogue, and it probably would not show a trickle discharge. But I know that the bilge pump is wired around the battery switch, so there might be other things. (Before anyone asks, the bilge pump is not running, the bilge is very dry and well below the level it would be if the float switch activated) Anway, buying a 25 year old boat is a voyage of discovery as I try to figure out what goes where and is attached to what. I'm off tho visit the boat again this weekend, (two weeks from the last visit) and I'll be measuring voltages again, and I'll see what I can hunt down that is still drawing.

 

[John]

No sand

No sand just use the right size bender.I make a pattern on ply wood and match it up for size and shape.The bender i have is 6' long Ive seen then at Home depo