Solar panels

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balticbound
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Solar panels

Post by balticbound » Sun Oct 27, 2013 10:47 am

Can anyone offer any advice on rating, make etc of solar panels needed for my boat? Major electrical items are 12v/240v Waeco fridge, 12v lighting in 3 cabins, eberspacher warm air heating, pressurised hot/cold water,immersion heater in calorifier, TV and DVD player. I also have a bow thruster but engine will be running when in use. I would like to be as self sufficient as possible and not depend upon shore power any more than necessary.

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Re: Solar panels

Post by steve parry » Sun Oct 27, 2013 11:48 am

Hi,

I don't know what type of Westerly you have but based on my Pentland which is running more or less the same as you but with the following differences:

I have Gas central heating but it still needs a fan to push the warm air around the boat.
All my lighting have LED bulbs, if fact I can put all of my cabin lights on and it still draws less than 1 Amp
My masthead tri light is LED.
My immersion heater in the calorifier will only heat when on 240V otherwise its the engine.
I also have radar, AIS, two GPS's 1 x Plotter and the normal wind/depth/speed instrumentation VHF and Navtex.
What have I got in the way of panels etc: 2 x solar panels total 90 Watts and a Rutland 504 wind generator(I have the 504 because my boat is ketch rigged and the bigger 914 blades would eat my mizzen!!!) I have no problems with power, in fact I dump power 25% of the time. Batteries play a big part in this and I have 2 x 110Amp heavy duty, deep cycle service batteries, with 1 x 110Amp starter battery for the engine. (Belt and braces!!)

I would recommend something like 100 Watts (ed) in solar panels and a Rutland 914i wind generator (or similar) With a HDRX control. This also depends on how much space you have to fit these, if sloop rigged, a gantry on the back would suit your needs.

I hope this helps, I am in the members handbook if you want to talk further.

Regards

Steve Parry ~ Walkabout

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Re: Solar panels

Post by steve parry » Mon Oct 28, 2013 10:22 am

Hi,

Just had another look at my last post...My fingers were doing the talking not my brain!! Under recommendations ie Solar panels, it should read 100 Watts not Amps. I will try and do better next time!!

Regard

Steve

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Re: Solar panels

Post by Vegable » Wed Oct 30, 2013 11:53 pm

I was looking into this about this time last year and came to the conclusion that solar panels are very much a secondary source of electric.
You have to consider where you are going to use your boat. The panels have to be perpendicular to the sun to get the maximum power and ideally you need to be in the lower latitudes as well. As the sun moves around the sky so your panels need to move around too. Sails, masts and booms will also shadow your panels so siting is paramount and bare in mind the wind shadow when sailing and tacking. The rating/wattage of panels is given at peak power which is generated at full voltage of 19v. So if you have say a 100w panel, it will generate 5amps max. (Volts x Amps = Watts) However voltage regulators limit the useful voltage to 14v (otherwide your battery boils) so the maximum power you can usefully use is 70w. (These figures approximate only). This power is only available in full sunlight. If it's cloudy, whilst the panel is still generating, it's only generating a fraction of its rated output.
Prices vary greatly depending on their useful life so consider how long you're going to keep your boat. Top quality panels last for around 20 years or so. The cheapest less than 5 years life.
A wind generator as Steve advises is very good as long as you aren't sailing down wind and anchored in wind sheltered anchorages. In the end, I chose an Aquagen towed water generator, and a wind generator and this gives me all I need. I have similar equipment to Steve including LEDs, and also have fridge, and TV & DVD entertainment unit. I have an eber. heating unit which really gobbles up electric and isn't used unless the engine is running as is the bow thruster and anchor windlass.
If doing long cruising, you should have battery capacity to support twice your daily consumption before recharging. Batteries are damaged if discharged more than half power, i.e. when the voltage has dropped to 12.3 volts using a digital voltmeter. A cheap Maplin one is all you need - less than £10. I have 5x 130ah deep cycle lead acid batteries - 4 as service batteries and 1 dedicated engine start.
Mike
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Re: Solar panels

Post by aquaplane » Thu Oct 31, 2013 7:20 pm

When I'm on my boat I can manage the power usage.

I have a fixed solar panel to look after the battery when I'm not there. If it actually recharges the battery I'm ecstatic. If it stops the self discharge that is all I expect it to do.

I wouldn't dream of wandering round the boat holding up the panel to get the maximum efficiency, or anything like it.

If the boat is tipping away from the sun or the sails are shading the panel it's a good thing, I'm sailing.

When I am on a cruise I run the engine and sometimes hook up to 240V, the solar panel is in the way more than useful.
Bob.
Centaur now sold. Boating from Tarbert.

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Re: Solar panels

Post by steve parry » Fri Nov 01, 2013 1:04 pm

Hi,
I wouldn't discount solar panels! I went into this quite deeply when I looked at 'extra power' issues and talked with a few companies who deal with eco-energy issues/problems, once I got my head round all of this. I then went to the suppliers and listened to them. The common theme with all the companies was that a mixture of solar panels/wind generator was the best solution: When the sun is out and it is blowing a bit you are getting excellent charging, when the sun is out and no wind (as the case several times this summer) You are still charging! If its raining and blowing you are still charging, If it's not blowing but overcast you are still charging!! Its a win - win situation on all accounts!!

I disagree that you only get a charge in FULL sunlight, unless I've got the only solar panels in the world that charge when it is cloudy, the charge maybe lower than full sunlight but it is a charge!

I agree it's not cheap to install, but you do have batteries which are topped up and you can have cold beer when you want it!! The Aquagen as suggested isn't a cheap option and I believe it has its limitations, you are also towing something through the water (slowing you down!) and you have to be on the move to generate extra power, while solar/wind will work when stationary and would still generate power.

This is a huge subject and some installations would not suit all people but the round the world sailors (Vendee, Ellie MacArther, Thompson etc) all used solar panels and in the more recent race they used a new water generator attached to the back of the boat (Hugo Boss had big problems with these) but They ALL had solar panels on which didn't fail.

Food for thought I believe -It's a big subject and costly, so you have to get it right first time!

Regards

Steve

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Re: Solar panels

Post by Vegable » Sun Dec 15, 2013 5:33 pm

There's been a very interesting discussion on Solar v Wind on the PBO forum. Well worth a read - it' runs over about 4 pages
http://www.ybw.com/forums/showthread.ph ... lar-v-Wind

Mike
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Re: Solar panels

Post by TyroSailor » Fri Apr 01, 2016 5:00 pm

Wouldn't a towed generator work when you're moored/anchored in a tideway? Or does it need a minimum speed through the water?

I'm going to have to get to grips with this problem in the not-too-distant as I want to be able to run my (so far purely conjectural) bilge pump from solar cells (via the battery) as well as keeping topped up when I'm not there.
Experience: That which would have been most useful five minutes before you acquired it.

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Re: Solar panels

Post by philipstevens » Fri Apr 01, 2016 5:50 pm

A problem I can see with having a towed generator on a tidal mooring, is wind over tide - when the wind is stronger than the tide, and the boat ends up stern to tide, and bow to wind, leaving the towed generator under the boat and probably tangled up with the mooring (or anchor).

A wind generator is always facing into the wind, no matter which direction the boat is lying. As long as there is wind, it is generating.

Solar panels usually produce more power than a wind generator, but don't seem to work well in the dark!

I had both on our previous Duo, and the solar panels were more efficient than the wind generator.
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Re: Solar panels

Post by TyroSailor » Fri Mar 16, 2018 2:30 pm

Bit of resurrection here.

I went back to the boat a few days ago after leaving her to her own devices over the winter (although it was checked by friends a couple of times - I live 300M way!). There's a little 10W solar panel on the engine battery and a new 50W panel connected to the domestic. After disconnecting the big panel and waiting half an hour for it to sort itself out, I measured 13.7V on the domestic battery! The engine battery was also at something over 13V after a few hours of darkness (I can't easily disconnect that one).

The panels are both mounted vertically on the rails, facing approximately south.

Dunno about you lot, but I'm happy with that. Yes I know that's not the only measure of a battery's state of charge....
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Re: Solar panels

Post by Vegable » Sat Mar 31, 2018 10:47 am

It's funny reading what I wrote a few years ago. I've now discarded the Rutland Wind genny, and have only used the Aquagen once. And guess what, I have 300w of sloar panels on board now. 2 x 100 are floating. I move them around the deck as and when I want them and even on cloudy days they give out enough power to keep the batteries charged up on long passages. What's more they are silent!
So, ignore most of my comments above and get solar
Mike
"There is nothing worse than running ashore, unless you are uncertain as to which continent that shore belongs"

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