Do I need to add a solar trickle charger?

[PhillM]

Following on from my thread about moving to a mid river trot, I was wondering if I should add a solar trickle charger, or not?

Wooden boat, occasionally gets a few pints in the bilge but not usually enough to run the bilge pump. I have a 92 AH engine start battery (which also has the bilge pump directly wired to it) and a 110 AH leisure battery.

Beta 14 with standard 40 amp alternator. Also have a CTek battery charger for when I am plugged in.

The plan is to visit the boat every month in the winter, to keep an eye on things. However, I tend to run antifreeze through the sea water side of the engine, so I do not usually run it in the winter. In the summer there will be enough motoring to keep everything charged and the odd marina visits, when I shall plug in and use the battery charger.

Thoughts please?

 

[VicS]

Following on from my thread about moving to a mid river trot, I was wondering if I should add a solar trickle charger, or not?

Wooden boat, occasionally gets a few pints in the bilge but not usually enough to run the bilge pump. I have a 92 AH engine start battery (which also has the bilge pump directly wired to it) and a 110 AH leisure battery.

Beta 14 with standard 40 amp alternator. Also have a CTek battery charger for when I am plugged in.

The plan is to visit the boat every month in the winter, to keep an eye on things. However, I tend to run antifreeze through the sea water side of the engine, so I do not usually run it in the winter. In the summer there will be enough motoring to keep everything charged and the odd marina visits, when I shall plug in and use the battery charger.

Thoughts please?

It would be a good idea.

Try to make a generous estimate of the maximum weekly Ah draw by the bilge pump if you do use it plus any other power you might use while on board.

Choose a solar panel which will supply this much, plus a bit extra, at your location during the winter.

Wire it, via fuses, to both batteries using a PWM controller with dual outputs.

My guess will be that something between a 10 and a 20 watt panel, depending on bilge pump use, will keep the batteries happy for the winter but generally the more solar power you can fit the more useful it will be.

 

[sarabande]

Yes, a 10 or 15 W solar panel will keep the batteries smiling. No controller needed, just a fuse on the +ve from the PV panel to the battery(ies). I run a baby panel as above into 2 x 110AHr domestics (the engine batt is isolated) and I have a consistent reading of 12.7v when I arrive on board. The panel is sunlit directly for about 4 hours a day.

How do you separate your batteries ?

EDIT

Beaten to it by VicS again

 

[simonfraser]

winter time the panel will work much better upright towards the sun, possibly on the side of the cabin.

 

[VicS]

Yes, a 10 or 15 W solar panel will keep the batteries smiling. No controller needed, just a fuse on the +ve from the PV panel to the battery(ies). I run a baby panel as above into 2 x 110AHr domestics (the engine batt is isolated) and I have a consistent reading of 12.7v when I arrive on board.

How do you separate your batteries ?

The reasons I suggested a dual output controller are that a controller is generally advise d for any thing over 10 watts, regardless of the battery capacity, and that a dual output one will keep both batteries charged without them being interconnected.

 

[sarabande]

That is certainly a more elegant solution than just charging one (set of) battery. Keeping two batteries smiling is a plus.

 

[davidmh]

Sarabande, you say that when you visit the boat the battery volts register full charge, to be realistic should you not disconnect the solar for a time and let the battery rest to get a meaningful volts reading.

David MH

 

[ex-Gladys]

winter time the panel will work much better upright towards the sun, possibly on the side of the cabin.

... to be accurate a solar panel is at its most efficient when the panel is at right angles to the sun - the perceived wisdom for a static panel is that the angle is approximately equal to your latitude... In the UK this means about 50-60 degrees. Vertical is not that different from horizontal

 

[johnalison]

I think that if fitting a solar panel, and possibly a controller, I would be inclined to go up a size and cater for possible future requirements. I have 36w mounted flat, and although it doesn't do everything, it will easily compensate for what I might use on a long day sail and cope with about half the fridge load at a low setting.

 

[sarabande]

Sarabande, you say that when you visit the boat the battery volts register full charge, to be realistic should you not disconnect the solar for a time and let the battery rest to get a meaningful volts reading.

David MH

10W solar panel is not a permanent fixture and is left mounted vertically at the front of the cockpit, connected dreckly to the domestic batteries. Boat is moored as near as dammit N and S.

I do have a Victron controller, but it's one of the winter jobs to wire it in, so that I can find how many AHr the panel produces. With 12.7 showing a couple of minutes after I have disconnected the panel, I am happy the topping up process has been carried out and that I don't need to do a drop test.

While the boat is out of the water for the next month, I'll use a spare battery for on board services, and take the boat ones home for the Ctek charger to perform a thorough stir up and deep charge.

At my last count, I have three separate solar panels, three battery chargers and eleven batteries installed in tractors, quads, boat and sheds. It's a nearly full time job !

 

[PhillM]

Thanks guys, most helpful.

Bit of a silly question, but does it affect total performance if there is a shadowy on the panel? For example the most convienent place for it is on the coachroof, but that would mean the boom could cast a shadow. Does that stop just the part of the panel with the shadow on it from working, or the whole panel working at all?

 

[sarabande]

Some panels are sensitive to a shadow, others less so. I think it is down to clever (and hence expensive) design of the connections between the individual cells. Can you check it out with a voltmeter before you install it on the boat ?

 

[PaulRainbow]

Thanks guys, most helpful.

Bit of a silly question, but does it affect total performance if there is a shadowy on the panel? For example the most convienent place for it is on the coachroof, but that would mean the boom could cast a shadow. Does that stop just the part of the panel with the shadow on it from working, or the whole panel working at all?

Shadow will have an effect, but it will not stop the panel completely if part of the panel is shaded. I have a pair of 30w panels on the coachroof that suffer with shading, but still deliver some useful power. Obviously best if you can avoid it, i also have a pair of 100w panels on an arch at the transom that do not get any shade and are vastly more efficient.

 

[William_H]

Yes to the question should I fit a solar panel. For the cost the benefits are huge. However it is the location and fitting of a solar panel that is difficult. If you are on a swing mooring the boat will face each and every which way so horizontal is as good as anything. A larger panel will give more average charge and winter in UK on a swing mooring will be the worst conditions. I don't know about shadow from the boom perhaps not the best place to locate the panel as it would always have some shadow. I mount my small one (5w) on top of the boom attached by bungees. I remove it before sailing. No it has not been nicked after a few years compared to fixed panel which inevitably got broken by gear or feet. But you may have guessed sunshine is not something we are short of and I don't use it in winter. So give a solar panel a go it can only help the battery charge. olewill

 

[alant]

Following on from my thread about moving to a mid river trot, I was wondering if I should add a solar trickle charger, or not?

Wooden boat, occasionally gets a few pints in the bilge but not usually enough to run the bilge pump. I have a 92 AH engine start battery (which also has the bilge pump directly wired to it) and a 110 AH leisure battery.

Beta 14 with standard 40 amp alternator. Also have a CTek battery charger for when I am plugged in.

The plan is to visit the boat every month in the winter, to keep an eye on things. However, I tend to run antifreeze through the sea water side of the engine, so I do not usually run it in the winter. In the summer there will be enough motoring to keep everything charged and the odd marina visits, when I shall plug in and use the battery charger.

Thoughts please?

An RAC guy recommended one for my wife's car, when the 'newish' battery ran down following the recent cold weather. Only £15 in Halfords & £10 in Maplin. Any better deals about?

 

[whiteoaks7]

Firstly: shading can stop a panel virtually completely depending on the technology - you would want a crystalline panel because that's most size-efficient but then shading is a real issue because cells in the dark feed off the cells producing power and hammers down the overall output.

Secondly: if you want a bit of science to it all read the PBO article here: http://www.pbo.co.uk/expert-advice/solar-panels-everything-you-need-to-know-24455 At the bottom you will find how to calculate the amount of radiation you can expect at your location by month and the best angle for the panel to be at.

 

[ghostlymoron]

If you're on a swinging mooring,
the best angle is horizontal or a couple of degrees either way to encourage draining.

Firstly: shading can stop a panel virtually completely depending on the technology - you would want a crystalline panel because that's most size-efficient but then shading is a real issue because cells in the dark feed off the cells producing power and hammers down the overall output.

Secondly: if you want a bit of science to it all read the PBO article here: http://www.pbo.co.uk/expert-advice/solar-panels-everything-you-need-to-know-24455 At the bottom you will find how to calculate the amount of radiation you can expect at your location by month and the best angle for the panel to be at.