solar panels

[dor]

I'm tempted by the idea of getting a small solar panel to help top up my batteries during the week.

 

Ideally they would sit on the roof at an anlge, facing south. Howevre being on an on-line mooring, I suspect a panel sitting on the roof might be just a bit too tempting to passing riff-raff.

 

So, I could leave it inside the boat, up against a window, or put it in the cratch where it would be a bit less secure, but might be in a better position.

 

The question is, how much is the output of the panels affected by being behind an extra layer of glass?

 

Anyone have any experience of this?

[Ricardo]

I have a 28w solar panel in a window on my boat and it's working about as good as when I lay it flat on my cabin roof, I'm assuming the slightly better angle to the sun off sets the loss due to the glass in the window, and this can only improve as the sun gets lower in the sky.

 

I ran my batteries a bit too low one night, my radio lost it's display, and the batteries were back to 12.6V by noon the next day. Although this sounds good it's not really because the regulator then stopped sending the charge to the batteries and a 28w panel producing just under 2A can't possibly fully charge 2x110A batteries in 5 hours. I think I just need a better regulator, the one I have came with the panel.

 

The point is though that the solar panel works well enough in the window and after 5 hours the radio was back to normal and the lights didn't dim when the water pump kicked in.

 

If you got a panel 15w or less you wouldn't need a regulator so you'd be getting a small charge whenever it was sunny, if you're away from the boat all week that'd probably give you as much charge as a bigger panel that was regulated, and therefore doing nothing for a couple of days.

 

Ric.

[DHutch]

We;ve got two of the BTsolar/Solerex pannels, which are slimline and backed on S.Steel.

- There about 4mm thick, can be walked on, and can be curved enough to follow the roof.

- We plan to mount them onto the wheelhouse roof using allan-head bolts, with double nuts (backed onto each other)

 

Hopefully this will be a good enough location for them without the need to alter there angle as the boat moves, or worry about them being pinched!

- Also the you dont really see the top of the wheelhouse roof in normal passing as its slightly above normal eyeleval.

 

Now all we have to do is acctally get around to fitting them! At the moment there carefully being protect from UV damage, in there box, under the bed!

 

 

 

Daniel

[awatsonbcp]

Being a jock all i would like to know is how muich does a 28 w solar panel cost ?

[DHutch]

Ours are 20w each, and a beleave they cost around the £100 mark. (£200 for the pair, to make a 24v pannel)

 

 

Daniel

[dor]

Some prices here:

 

http://www.selectsolar.co.uk/kit.php

[Nige]

I'm tempted by the idea of getting a small solar panel to help top up my batteries during the week.

 

Ideally they would sit on the roof at an anlge, facing south. Howevre being on an on-line mooring, I suspect a panel sitting on the roof might be just a bit too tempting to passing riff-raff.

 

So, I could leave it inside the boat, up against a window, or put it in the cratch where it would be a bit less secure, but might be in a better position.

 

The question is, how much is the output of the panels affected by being behind an extra layer of glass?

 

Anyone have any experience of this?

 

 

Hi Dor,

 

I have two of these panels:-

 

http://cgi.ebay.co.uk/SUPERIOR-METAL-FRAME...1QQcmdZViewItem

 

I've had them for just over a year now, mounted outside on Discovery's roof and can highly reccomend them. Not had any experience of mounting them behind glass, but for the money (£70 each INCLUDING postage) you cant go wrong. In decent sunlight they put out 18 watts and I have had them charge a 90 amp leisure battery from totally flat to full in just under 3 days. Im looking to add another 2 later this month.

 

Nige

[Yoda]

Hi Dor,

 

I have two of these panels:-

 

http://cgi.ebay.co.uk/SUPERIOR-METAL-FRAME...1QQcmdZViewItem

 

I've had them for just over a year now, mounted outside on Discovery's roof and can highly reccomend them. Not had any experience of mounting them behind glass, but for the money (£70 each INCLUDING postage) you cant go wrong. In decent sunlight they put out 18 watts and I have had them charge a 90 amp leisure battery from totally flat to full in just under 3 days. Im looking to add another 2 later this month.

 

Nige

 

They would be ideal to recharge bow thruster batteries in the front of the boat.

[Yoda]

They would be ideal to recharge bow thruster batteries in the front of the boat.

 

Can't believe I have got away with this for this long. The mention of BT is 'very topical'.

[DHutch]

You certinaly could use the solar pannels to top up the thurster batterys.

- However, like anything else the draws a lot of juice, you would a fair bit of solar pannel(s) to make a significant diffrence.

- Also, as you basicaly only use the thruster while moving the boat, you will almost certainly have the enigne running anyway!

 

When we get them fixed on the roof our solar pannels will be wired up two charge all three of our batterys banks, the two domestic banks, and the bowthruster batterys. (we have no start battery) Using a primative split-charge relay setup.

 

 

 

Daniel

 

The, i said it.... (doh!)

[Yoda]

You certinaly could use the solar pannels to top up the thurster batterys.

- However, like anything else the draws a lot of juice, you would a fair bit of solar pannel(s) to make a significant diffrence.

- Also, as you basicaly only use the thruster while moving the boat, you will almost certainly have the enigne running anyway!

 

 

Yes daniel but you would not have to run heavy cables to the bow!

[David Schweizer]

Putting the Ecological arguement to one side, I have never been able to understand why people will cover their boat with solar panels which will produce the same amount of electricity as running the egine for 10 minutes, and that is when the things work at full output. It just doesn't make economic sense.

[stuart]

Putting the Ecological arguement to one side, I have never been able to understand why people will cover their boat with solar panels which will produce the same amount of electricity as running the egine for 10 minutes, and that is when the things work at full output. It just doesn't make economic sense.

 

If you have no electric point at your mooring and you leave your boat for a few weeks at a time, they could be useful to top-up your batteries - effectively for free.

[dor]

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Putting the Ecological arguement to one side, I have never been able to understand why people will cover their boat with solar panels which will produce the same amount of electricity as running the egine for 10 minutes, and that is when the things work at full output. It just doesn't make economic sense.

 

Although the solar panels only produce say 1 or 2 amps for say 8 hours a day, that is say 50 or 60 amphours. I would have to run my engine for 2 or 3 hours to get that, not 10 minutes - I only have a small alternator.

 

In the winter, if I go out overnight, we might only travel for an hour or so, so never really replace what we use overnight.

 

Although solar panels only produce a small current, what it lacks in amps is made up for by hours. As I can't fit a larger alternator, I need something to increase the recharging in the winter.

[David Schweizer]

If you have no electric point at your mooring and you leave your boat for a few weeks at a time, they could be useful to top-up your batteries - effectively for free.

That is the standard sales pitch for these things. I do not have any power at my mooring, and I leave the boat for anything up to four weeks between visits in the winter. I always check my batteries when I visit the boat and there is never any measurable drop in voltage, so the arguement for the need to "top them up" is superfluous. If I do run the engine, the charge usually floats for about ten minutes and then goes onto a trickle, hence the claim of ten minutes to top up the batteries.

 

 

Although the solar panels only produce say 1 or 2 amps for say 8 hours a day, that is say 50 or 60 amphours. I would have to run my engine for 2 or 3 hours to get that, not 10 minutes - I only have a small alternator.

As already stated, my batteries do not loose any measuranble charge over three or four weeks, so they do not require constant topping up. Yes it would take more than ten minutes to recover 50 amp hours, but if the batteries were that flat (and I would worry if they were) my alternator would bring them back to full charged in a little more than an hour.

 

I do not understand why you cannot fit a larger output Alternator, the higher output ones are a bit fatter but the fittings are the same. I can get a 55amp re-built alternator for less than £25, it is a much cheaper option to replace the alternator than fitting expensive Solar Panels.

 

I have done a similar excercise investigating the fitting solar panels on my house, and I would have to live about 200 years to recover the initial outlay (will they laast that long? - I won't) I am afraid that the maths do not add up when it comes to Solar panels.

Edited September 16, 2006 by David Schweizer

[Nige]

That is the standard sales pitch for these things. I do not have any power at my mooring, and I leave the boat for anything up to four weeks between visits in the winter. I always check my batteries when I visit the boat and there is never any measurable drop in voltage, so the arguement for the need to "top them up" is superfluous. If I do run the engine, the charge usually floats for about ten minutes and then goes onto a trickle, hence the claim of ten minutes to top up the batteries.

As already stated, my batteries do not loose any measuranble charge over three or four weeks, so they do not require constant topping up. Yes it would take more than ten minutes to recover 50 amp hours, but if the batteries were that flat (and I would worry if they were) my alternator would bring them back to full charged in a little more than an hour.

 

I do not understand why you cannot fit a larger output Alternator, the higher output ones are a bit fatter but the fittings are the same. I can get a 55amp re-built alternator for less than £25, it is a much cheaper option to replace the alternator than fitting expensive Solar Panels.

 

I have done a similar excercise investigating the fitting solar panels on my house, and I would have to live about 200 years to recover the initial outlay (will they laast that long? - I won't) I am afraid that the maths do not add up when it comes to Solar panels.

 

The maths add up perfectly if like my NB Discovery your leisure batteries are not wired into the very elderly generator (not alternator) that sits on the side of your engine.

As I mentioned in my post above, during the summer months I can charge a 90 amp battery from totally flat to fully charged, in a little under 3 days, and thats with two solar panels that put out a maximum of 18 watts.

 

Please dont state that the maths dont add up when im living positive proof that they do. I have the equipment in place, it's running, it works. Dont go for the theory - do the practical.

 

I will be eventually installing an alternator to charge the leisure batteries during the winter months, when obviously the solar panels output is drastically reduced. But im a big believer in getting something for nothing if I can, (I also have a Rutland wind generator) and during the summer months the solar panels work great.

 

Nige

[dor]

As already stated, my batteries do not loose any measuranble charge over three or four weeks, so they do not require constant topping up. Yes it would take more than ten minutes to recover 50 amp hours, but if the batteries were that flat (and I would worry if they were) my alternator would bring them back to full charged in a little more than an hour.

 

I do not understand why you cannot fit a larger output Alternator, the higher output ones are a bit fatter but the fittings are the same. I can get a 55amp re-built alternator for less than £25, it is a much cheaper option to replace the alternator than fitting expensive Solar Panels.

 

I never said my batteries lost power on the mooring. But if I go out in the winter, say an hours cruising. then spend the late afternoon and evening on the boat with lights, radio and/or TV, then cruise back in the morning, I'm not generating enough power to replace what I have used. Hence the need to top up the batteries. It is very difficult ot fit a larger alternator as the one that is fitted will just fit due to the shape of the exhaust header tank. I could make up new mountings for a larger alternator, but it is not an easy job, due to the position of the engine.

[David Schweizer]

I never said my batteries lost power on the mooring. But if I go out in the winter, say an hours cruising. then spend the late afternoon and evening on the boat with lights, radio and/or TV, then cruise back in the morning, I'm not generating enough power to replace what I have used. Hence the need to top up the batteries. It is very difficult ot fit a larger alternator as the one that is fitted will just fit due to the shape of the exhaust header tank. I could make up new mountings for a larger alternator, but it is not an easy job, due to the position of the engine.

No sorry, you did not, it was just that I could not think of why you would need to produce 60 amp hours to re-charge the batteries if the boat had been left unattended.

 

You do not say what the output of your Alterrnator is or whether you have an alternator regulator fitted. It is unlikely that the alternator Output will be less than 35amps, which shouild be enough to maintain all the items you mention and also recharge your batteries, although if you have an old type of alternator which will not deliver the full output, then it will not satisfy the demand because of the design of the internal regulator. If this is the case I would suggest considering the installation of an Alternator regulator, which would bypass the internal regulator and enable the alternator to maintain a much higher output, or a modern Alternator (if you can find one to fit)

 

I used to be in the same position as you, with the batteries being flat in the morning and 25 year old alternator taking hours to re-charge on. I now have a modern 55 amp alternator with a Sterling Digital Alternator controller fitted to my boat. I can moor up at 4pm, have all the lights on, watch the TV all evening, run the fridge all night, and an hours cruising in the morning will completely re-charge the batteries.

Edited September 17, 2006 by David Schweizer

[David Schweizer]

 

 

Please dont state that the maths dont add up when im living positive proof that they do. I have the equipment in place, it's running, it works. Dont go for the theory - do the practical.

 

 

 

Nige

No Nige, you are living proof that the maths only add up for the very small number of boats that do not have an alternator fitted to the engine, which you did not make clear in your original posting. My arguement related to the 99.99% of boats that have a conventional arrangement for charging the batteries, and I still stand by that arguement.

 

As a matter of interest I do have a friend who lives in a Caravan which is not connected to the national grid. He has four solar Panels and a wind generator, and in the winter he regularly takes his batteries down to the local garage to have them charged up. Not personal practical experience I agree, but the next best thing.

Edited September 17, 2006 by David Schweizer

[Blue_skies]

I have a 28w solar panel in a window on my boat and it's working about as good as when I lay it flat on my cabin roof, I'm assuming the slightly better angle to the sun off sets the loss due to the glass in the window, and this can only improve as the sun gets lower in the sky.

 

I ran my batteries a bit too low one night, my radio lost it's display, and the batteries were back to 12.6V by noon the next day. Although this sounds good it's not really because the regulator then stopped sending the charge to the batteries and a 28w panel producing just under 2A can't possibly fully charge 2x110A batteries in 5 hours. I think I just need a better regulator, the one I have came with the panel.

 

The point is though that the solar panel works well enough in the window and after 5 hours the radio was back to normal and the lights didn't dim when the water pump kicked in.

 

If you got a panel 15w or less you wouldn't need a regulator so you'd be getting a small charge whenever it was sunny, if you're away from the boat all week that'd probably give you as much charge as a bigger panel that was regulated, and therefore doing nothing for a couple of days.

 

Ric.

Do you mind me asking how you got on with these panels? Thanks

[Bones]

I would like to secure my solar panels to the roof. There are 2 holes in on each short side of my 84W panel so I thought I would put some wire rope through each hole and then around my roof bar fixings.

 

How do I put in loops at each end of the wire loops once I have threaded them so that I can use a padlock?

 

wire rope

 

fixings

 

to equal something like this but in the wire rope:

 

loops

the loops need to be nice and secure.

[magnetman]

Use a flemish wire eye splice followed by swaging of the ends or you can just tape them up with strong duck tape. This is secure enough to stop people tampering with it. However wire rope is quite easy to cut with the right tool...

simple diagram of how to form a flemish eye (in 7 strand wire rope):

 

http://www.safewaysling.com/wirerope_sling.jpg

 

 

The example pictured has a swaged fitting however if this was omitted the completed eye would have two ends where the swaged fitting is, leave the extra end a couple of inches long and seize or tape that to the main standing part. The flemish eye requires no tools unlike proper wire eye splices which are much more complex. Being wire rope it will tend to lay back into its own form very readily.

Edited February 25, 2007 by magnetman

[Bones]

Use a flemish wire eye splice followed by swaging of the ends or you can just tape them up with strong duck tape. This is secure enough to stop people tampering with it. However wire rope is quite easy to cut with the right tool...

simple diagram of how to form a flemish eye (in 7 strand wire rope):

 

http://www.safewaysling.com/wirerope_sling.jpg

The example pictured has a swaged fitting however if this was omitted the completed eye would have two ends where the swaged fitting is, leave the extra end a couple of inches long and seize or tape that to the main standing part. The flemish eye requires no tools unlike proper wire eye splices which are much more complex. Being wire rope it will tend to lay back into its own form very readily.

 

can't I just put on loop the end? How do I tighten the thing the loop goes through? I'd rather it was secure and don't want to use tape.

 

How are your secured? I had hoped to put a bolt through the holes and then a chain, but the holes aren't big enough, and making them bigger might not result in anything suitable.

[magnetman]

I have my solar panels bolted to angled frames, which are then bolted to the roof (threaded hole) so it pivots around the securing bolt. You'd need someone with a swaging machine to crimp proper eyes in the wire rope, the flemish eye is a home-made version of it without tools being required. Or could use cable clamps. Wire rope if less than about 8mm is fundamentally unsecure because pocket sized tools are available to cut it very easily. Hardened chain would be the best thing because bolt croppers are a bit blatant to carry about.

I think the only way to secure them properly is to bolt them down.

 

As the frame of most solar panels is thin aluminium it is difficult, short of bolting them down, to secure them against planned theft but a wire rope (with flemish eyes which are perfectly secure and difficult to undo) would stop the opportunists.

[bottle]

Hi Bones

 

Simple way just make loop in end of wire and use two of these (screwfix) at each loop.

 

A good idea to tape the ends as well, they can be nasty if you catch yourself on them.

 

You could always put a second nut on each thread to 'lock' them so that it would be more difficult for the casual 'nerd' to undo..

 

Edit: double posted.

Edited February 25, 2007 by bottle