Right then, how shall I mount my solar panel?

[Iain C]

OK, so thank's to Salinia's heads up on the Maplin solar panel offer, I've just bought one. It's this one...

http://www.maplin.co.uk/solar-power...im635X493478Xcb19ed56e11f15c8d51d335d6760a18b

...and it's actually quite big and heavy. I want to mount it permamently and I don't want to spend a fortune. I'm looking for some creative ideas how best to mount it, probably somewhere around this cockpit. Please note, that photo was from the first time we sailed the boat, so the washboard no longer lives there, and the danbouy lives in a drainpipe mount lashed to the port side of the pushpit. The Forgen mount also has stays on it now.

Clearly, I'm going to need to mount the panel onto some kind of ply backing piece, and I was originally thinking of trying to come up with some kind of moveable clamp system so I could mount it on the Forgen mast.

Now I'm thinking of mounting it on the backstay. If I got a couple of bulldog clamps and mounted them gently on the split backstay, just above head height, it would give me two "stops" to where I could somehow mount the panel, with it's long side against the split backstay, and obviously behind the backstay, above the ensign, out of the way. I could then take a rope from the back edge of the solar panel (the one furthest aft, away from the backstay) to a point about a metre up the "single" backstay (above the backstay splitter plate) where I could rig up a dinghy style trapeze cleat which would enable me to in effect alter it's angle to the sun, by changing the height of the back of it. Might even be some mileage in attaching it to the backstay with jubilee clips in rubber mountings so I can tilt it to account for heel.

Does anyone have any better ideas?

 

[VicS]

At 4kg it is going to need some solid mounting arrangements.

Screwed down firmly to the deck I would think, not dangling in the rigging.

 

[vyv_cox]

Additional to Vic's point, you need to assess realistically what the panel is going to give you. At 12 watts the power it will provide when you are sailing is negligible. The best you can hope is that it will recharge the batteries during the week. As Vic says, mount it on deck. Put it as far from the mast as possible to minimise shadow, maybe on the hatch garage.

 

[bluerm166]

solar panel mounting

I believe that even the thin shadow of the stays will interrupt the charge on one or more segment of the panel,so if it were on the backstay you would need to orientate the boat at its mooring accordingly.You still get the same issue with the other stays but distance from them reduces the problem.We have our panel on the hatchtop (altho its a lighter flexible type) and secure the boom well off centre,leaving the boat in the same orientation bewteen trips.

 

[ProDave]

I believe that even the thin shadow of the stays will interrupt the charge on one or more segment of the panel

I think that may be true of some multi segment panels, but this is all one piece, one panel.

The tests I have been doing on mine inside my workshop window seem to indicate that casting a shadow, in either axis, has little effect on the output.

but I agree with the others, it needs to be fixed.

In my case, at least for this season, I am just going to hang it inside the boat against a window while the boat's not at sea, and stow it securely when we go out. I will look at possible fixed mounting positions next winter when the boat is at home on the trailer and easier to work on. The main "problem" is trying to mount a flat object, somewhere on a curved coach roof.

And yes the output is small. We are hoping a weeks charge will be enough for a few hours use of the VHF, plotter and log so we don't have to take the battery home for a charge (no charging from my OB)

 

[VicS]

And yes the output is small. We are hoping a weeks charge will be enough for a few hours use of the VHF, plotter and log so we don't have to take the battery home for a charge (no charging from my OB)

I have not needed to take my battery home for charging since I first fitted a solar panel and thats only 5 watts!

I must admit I dont have plotter ..its only a 19ft boat and i dont go far enough to need anything like that .. Don't even get the chart out sometimes and I very seldom transmit on the VHF.

The Autohelm runs nearly contiuously though.

In theory the outboard charges but only in theory.

 

[Iain C]

Hmmm. Orientating the boat is a waste of time as she's on a swinging mooring. I don't have a hatch garage, the hatch just slides forward under the sprayhood and out onto the (curved) coachroof so there's just not enough room. Besides, all it takes is one careless dropped spinnaker pole and the panel is history.

Re shadows, I really can't see how one backstay will make that much difference compared to the shadows cast by the boom, kicker, stackpack, shrouds, mast, spreaders etc that would get cast if it was on the coachroof. Bar the top of the mast, it's probably in the sunniest position right aft.

Personally, I don't think that it would be that unstable aft either...I've drawn a picture below and you can see that it's held in four places (there are only four mounting holes on the actual panel anyway) and if things got stupidly windy it could always be stowed below (although I reckon I'd have bigger issues than the solar panel!)

If you think that my idea is seriously a no-hoper then fine, I will take people's advice and give up, but no-one worries too much about a boom dangling round in the rigging, and in effect this is the same, with a gooseneck, a topping lift and a mainsheet!

(Edit...Hmmm...I've just re-read that and it comes across as "I know best"...which I don't! All feedback more than welcome, if people think that it won't be safe back there, or it's more hassle than it's worth for the power, then no worries. The boat usually gets out every second or third weekend, so there's plenty time for it to charge up on the mooring! Also, the mount for the panel would be a frame, rather than one large panel, to assist with heat dissipation and save weight. The bungee between the panel and the transom could get swapped for some more dyneema if it wobbles around too much.)

 

[salinia]

Would fastening it to the backstay perhaps bring on early corrosion of the stainless steel rigging at the fastening points? I wonder if it you would be able to fasten it aft of the the pushpit by obtaining some type of bolt on stainless steel pipe bracket that could be folded in when not in use...a close eye on ebay might come up with something that you could utilise at some later date so as to keep the price down. I intend to mount ours on top of the boom cover angled with the main halyard when not aboard and see how it performs.

 

[Iain C]

Hmmm, as the fittings could easily be moved, I don't think there's too much of an issue there, and a quick smear in lanolin grease should hold any corrosion at bay. It's certainlr far more accessible than what it lurking under spreader boots!

 

[sarabande]

I would be quite concerned about the voltage drop between the panel and the batteries. And as you are only starting off with well less than 1 amp under optimum generating conditions, I think the panel needs to be as close to the batts as poss,, not (say) a 5 m cable run away.



Given that the boat is going to be left for a fortnight at a time, perhaps you might be better to locate it on the cabin top when you leave, and put it down below when you arrive.

I think you may be disappointed by the performance if attached to the backstay.

 

[Iain C]

Oh dear! This really is not looking too positive, I'm starting to have doubts!

For whatever reason it always seems to take ages to put the boat to bed, in terms of mooring, cleaning the deck down from the yukkiness that falls off the mooring chain, all the usual checks, getting the dinghy sorted and the engine on it, gear off, anti halyard clanky stuff on...the last thing I want is another job on the list, as the Sunday traffic builds up!

As the batteries are right next to my companionway steps, the shortest useable cable run will be from there straight back in the engine room, popping out on the aft coaming somewhere and up the backstay. It's got to be shorter and less hassle than running it under the headlining etc back to underneath the quarter berth. And I still maintain it's going to get a lot more shadow on the coachroof than up the backstay!

But, there's some very knowledgeable people on here so I will happily bow to superior wisdom than to waste a weekend only for a "guys, you were right, it did'nt work" result!

 

[sarabande]

Iain

that panel will give you some charge, no doubt. But so little that you need to optimise the position and the infrastructure.

I like the arrangement you have sketched out for the back stay, it's a practical and fun low-cost solution.

How many batteries do you have on board ? I guess two ? What size ? Would it be possible to fit quick release connectors to the terminals of one of them, and leave it re-connected in the lazarette just below the panel on the backstay ?

(You wanted creative ideas !)

Perhaps you might look at the IP rating of the panel, too. Is it waterproof ? What do the instructions say about where it should be mounted ? A salty wind could leave creeping moisture if the edges are not properly sealed.

 

[VicS]

I would be quite concerned about the voltage drop between the panel and the batteries. And as you are only starting off with well less than 1 amp under optimum generating conditions, I think the panel needs to be as close to the batts as poss,, not (say) a 5 m cable run away.



Given that the boat is going to be left for a fortnight at a time, perhaps you might be better to locate it on the cabin top when you leave, and put it down below when you arrive.

I think you may be disappointed by the performance if attached to the backstay.

The cable can be sized to keep the volts drop within reasonable limits .
Easy enough to look up cable resistances and work it out from first principles
Alternatively
There is a calculator to determine the cable size HERE

Volts drop is no where near such a problem between a solar panel and the battery as it is between the battery and say a tricolour light because the solar panel has such a high open circuit voltage that to some extent it compensates for the volts drop in the wiring while a small voltage drop in the supply to a light will result in a much dimmed output!

 

[Colin K]

Opps

Golly I have a different view on this. My panel is slightly bigger.
I changed my split back stay for a twin set up which gave me a new back stay set up that I could forget about for 10 yrs. Once done it gave me a great set of stays to fix a panel to and it has worked well for a couple of years now. I check for signs of corrosion and none so far.

All the best, Colin.

 

[ProDave]

Cable length and voltage drop is insignificant.

For a start, the panel is supplied with 5 metres of cable.

It only provides a maximum of 1 amp. You would have to be using a VERY long cable, or a VERY thin cable for the voltage drop to be significant.

So don't let cable length in any way influence your decision where to put the panel. If it really bothers you (it shouldn't) use a thick cable.

 

[VicS]

Cable length and voltage drop is insignificant.

For a start, the panel is supplied with 5 metres of cable.

It only provides a maximum of 1 amp. You would have to be using a VERY long cable, or a VERY thin cable for the voltage drop to be significant.

So don't let cable length in any way influence your decision where to put the panel. If it really bothers you (it shouldn't) use a thick cable

For the reasons above its not so critical between a solar panel and the battery but generally dont underestimate the effects volts drop in cables when you only have 12 volts to start with! Once the cable run gets to about 2 metre volts drop on 12 volt sytems starts to become a more significant factor that the safe current carrying capacity of the cable.

 

[fishermantwo]

Not too keen on the backstay idea. Most yachts here use SS arches over the stern which I hate. Lot of weight in the wrong spot and I don't like anything that effects sailing performance and I use a windvane self steering. There is a chance the panel mounted using the backstay could set up an annoying vibration at some angles.

One of the better installations locally, the yacht has a 20 watt panel mounted on its edge either side of the pushpit[2]. Normally they sit vertical but have an adjustable lower arm that varies the angle so they can be set horizontal. Talking to the owner he says that he actually leaves them vertical in fact and they provide more than enough power. I intend doing the same but with a pair of 10 watt panels and mount them closer to 45 degrees similar to the highway solar panels. On a swing mooring they will look after the batteries and while sailing one of them will be horizontal.

 

[William_H]

For the reasons above its not so critical between a solar panel and the battery but generally dont underestimate the effects volts drop in cables when you only have 12 volts to start with! Once the cable run gets to about 2 metre volts drop on 12 volt sytems starts to become a more significant factor that the safe current carrying capacity of the cable.

Vic nonononono You have in most solar panels 20v to start with. Oh hang on (I see you are referring to 12v systems in general.) Solar charging is not like that at all As you said.
A solar panel can be described as having an internal resistance of for 10 watt panel about 40 ohms. So one additional ohm in cable (which is a lot) will make no effective difference. The internal resistance is what makes it Ok to connect a 20v panel to a12v battery. So just use the cable supplied. Small is OK but larger is more robust and resistant to corrosion etc.

Back to OP I have of recent times mounted my panel (a bit smaller) on bugees and it is laid on top of the boom and sail cover. I remove it before each sail. I have tried on the front hatch cover but yes it got speared by a spin pole.
Some people around here use a single pole on the pushpit with a clamp type bracket to allow orientation north at a suitable angle. 32 degrees. However unlike you and I they are moored in a fixed direction to a jetty.
Your idea of hanging it on the backstay is good. The backstay has lots of strength . You could make up SS rod which clamps in 2 places on each backstay leg then out horizontally. Or use 2 rods as a support from under neath with the front attached as you had in mind. Do not try to angle the panel as this will be then be good in some directions and very wrong in other directions of boat heading. Of course all these options means no adjustment of backstay when sailing. good luck olewill

 

[sarabande]

olewill

I suspect that being a Maplins special item, it will not be quite so efficient as a pukka job. They claim 17.5 "optimum" volts, but do not state where that is measured - e.g. up/downstream of the diode set, at the boat end of the 5m supplied cable....


In the end it doesn't matter. The OP is going to get some charge into his batteries while he is away. It may not be as much as a bigger/smarter/ polypv panel, but with the dinky Forgen and this panel, he will be sure of getting some charge in most of the time.

IainC - how are co-ordinating the inputs from the wind genny and the pvpanel ? I wonder if you are on the edge of needing a controller for a combined input under windy and sunny conditions ?

 

[Iain C]

OK...there's no backstay adjustment anyway bar the bottlescrews so that's not an issue.

I guess it boils down to two things...

Electrical/performance. Basically, is it worth it. If it means that on hot sunny days I'm more tempted to keep my coolbox on (that's the thing I really want to do, and the more sun there is, the colder the beer needs to be!), and on top of that after a couple of weeks on the mooring my batteries are in a better state, then that's good. I'll have a look at the spec of my coolbox and perhaps someone with more electrical knowledge can tell me if it's going to make any kind of meaningful contribution. And can I definitively run 4 or 5m of cable from the panel to the battery without any significant loss of charging performance...I'll measure the the exact cable run distance next time I'm on board. If that's a yes, then I'll look at the mounting.

I'm rapidly coming to the conclusion that the backstay is the ONLY place to mount it. I simply don't want to have to rig/derig it. There's too much stuff on the puspit, I don't want to whack it with the outboard, or for it to get in the way of launching MOB kit in an emergency.

What I will do is simply use a panel of MDF cut to the same size and give it a dummy run on the backstay and see if it's all stable enough. If it is, game on, if not I'll give up!