Is this worth doing? solar question

[GUMPY]

I have very limited roof space to put a solar array.

About the maximum size that I can fit is this:

 

http://pages.ebay.com/link/?nav=item.view&id=261083667740&alt=web

 

It would be taken down and stored when not in use.

 

Is it going to make a enough of difference when I am moored up or should I just run my engine for another hour?

Have all led lighting and a 230v fridge with sleeping inverter plus television and sat box both under 2 years old.

According to SG fridge takes approx 18% of my 3x125Ah batteries in 24hrs (SG went down by 6% whilst I was asleep with nothing else on.

Edited May 15, 2014 by Loddon

[bottle]

On a day like this, sunny, they will run your fridge and put some charge into your batteries.

 

So they may save you an hours engine running, no guarantee on this as there are to many variables.

 

Even on a dull day they will mitigate the fridge load.

 

For instance your fridge may have a load of 3 amps (when running) and at max output these will supply about 5 amps so they will run the fridge and put 2 amps towards the battery. When fridge is not running it will put the 5amps towards the batteries.

 

All this info is to help you decide whether it is for you and in no way a recommendation .

[Richard10002]

If you live on your boat, or use it every day, 100W is not much use.

 

If you spend 2 or 3 days a week on board, (or less), and leave the batteries more or less topped up when you leave, (say 80% or more), 100W will probably get them to 100% and keep them there, during the 4 or 5 days you are not on board - this assumes you turn everything off when you leave.

[GUMPY]

If you live on your boat, or use it every day, 100W is not much use.

 

If you spend 2 or 3 days a week on board, (or less), and leave the batteries more or less topped up when you leave, (say 80% or more), 100W will probably get them to 100% and keep them there, during the 4 or 5 days you are not on board - this assumes you turn everything off when you leave.

Although we live aboard and have done for over 20 years, when on the moorings we have 230v power from the grid.

So this is really only for use when we are away, 4 weeks or so a year, and when we decide to spend more than one night in any one place just. Normally when away we don't spend time moored up prefering to be moving rather than moored, last year however some days we only moved for a couple of hours and its times like that when it might help.

[jodansgang]

Remember, when you're traveling, the effects of the solar will be cancelled out by the alternator.

If you travel by day and stop by mid afternoon the suns position may be low and the effects on the solar be limited.

[GUMPY]

Remember, when you're traveling, the effects of the solar will be cancelled out by the alternator.

If you travel by day and stop by mid afternoon the suns position may be low and the effects on the solar be limited.

Solar would be packed away except when in use. If I stopped mid afternoon that would normally be after 8-9hrs boating, we start early.

[Arthur Brown]

IMO and only that, for the odd day in an otherwise mains powered year protect the starter battery from discharge and use the house battery more deeply. £150 for a solar panel for the odd day of use is madness. £150 would buy you the batteries not just the electricity!

[GUMPY]

IMO and only that, for the odd day in an otherwise mains powered year protect the starter battery from discharge and use the house battery more deeply. £150 for a solar panel for the odd day of use is madness. £150 would buy you the batteries not just the electricity!

Good thought £150 is half the battery bank I might just wait and get a bigger bank next time.

[Richard10002]

I would say that, if you are on board, using power, 100W would have hardly any effect.

 

I have 100W and, when I'm in board, it's not worth having. When I leave the boat for a few days each week, with everything turned off, I always come back to at 100%.

 

If you top your batteries up with 8 or 9 hours cruising, then have a full day and two nights without running the engine, (36 to 40 hours or so), you might use about 100Ah, which is only a third of your nominal capacity. A couple of 8 hour days of cruising will see this topped up again.

 

A 100Ah panel might give you 5Ah for 8 hours if it was positioned perfectly, the sun was hot and high, and the panel was efficient. Thus, in optimal conditions, you might get 40Ah during the day.

 

Don't forget, these 40Ah would be the first Ahs input by the alternator the next day, so only about an hour or two of cruising?

 

My own experience tells me that I would need at least 300W to have a meaningful effect when you're onboard.

[Paul's Nulife4-2]

Hi ya,

With my Simple take on things, I would suggest -

If you can afford an installation of whatever total wattage, that can be Fitted and forgot in a unobtrusive location,,, Do it, it's going to be worth it even if it isn't performing at 100%.

https://db.tt/WkiFue5A

I think the moment that you have to start to unpack, Mount, Tilt and Track, De mount, Pack away, making the whole thing very 'Portable and Manageable' !. Could be problematic to say the least in my view.

as I say,It works for me anyway, & I just enjoy it's harvest,however big or small.

Happy sun hunting !.

Edited May 15, 2014 by Paul's Nulife4-2

[GUMPY]

Problem I have is that the way I boat I use the centre ropes (I have one each side) a lot when locking. So that rules out anything angled and fixed on the rear 2/3 of the boat, hence the portable idea. I could put something larger on the front 1/3 next to the poles but then we are looking at 12+metres of cable losses.

Edited May 15, 2014 by Loddon

[Paul C]

There's one scenario where solar is more or less useless:

 

Leisure boater, who moors somewhere with a mains hookup, and when they don't use the boat its left hooked up. When they do use it, they cruise full days of approx 6-8 hours (or more), then stop in the afternoon/evening and use whatever stuff in the night such as TV, etc. In this scenario, the evening/night discharge doesn't really get served by the solar that well, because its evening time (sun is less strong) - yes there's a bit, but its marginal. Then in the morning, the solar power hasn't had a chance to properly have a go at recharging the batteries before the engine is started, and when this occurs, the alternator does the bulk of the charging (and if solar wasn't there, it would just do a little bit more - well within its capability. By around 5-6 hours, the batteries are pretty much fully charged.

 

Looking at another scenario, the above but with no hookup available, solar IS useful because it keeps the batteries topped up to 100% on float. Also, if its large enough (basic calculations suggest around 200W, maybe a bit less) its possible to leave the fridge on and keep the batteries at 100% too.

 

Another slightly different scenario: same as either above, but instead of 6-8 hour days, one's cruising is more like 3-4 hours, or there's the odd day or two like this. Solar starts becoming useful, because if well managed, you'd not need to run the engine while not cruising.

 

Obviously if you start using the boat while static and not running the engine, at this time of year solar (of enough power to match your needs) is a viable alternative to running the engine.

 

 

Sizing it all comes down to a formula with these 4 variables:

1) Roof space available

2) Power used in a typical or atypical discharge cycle, eg a typical evening's use and the size of the boat etc

3) How much of the 'season' (year) you'd like to be able to not run the engine.

4) The relative cost of diesel/other charging fuel (eg generator), and capital cost of solar installation

 

For example it might be worth using a little diesel say 1-2 hours per day running in March and October, rather than investing in more and more panels, to serve the power needs.

Edited May 15, 2014 by Paul C

[Lesd]

Hey Julian

When your away from your mooring you're on holiday, surely you dont want to spend time putting that contraption up every afternoon and down again every morning, that sounds like work !

Les

[GUMPY]

that's the lines of thought that I have been going down.

Much as I like the idea of solar unless circumstances or roof space change I think that the cash would be better spent on enlarging the battery bank next time I replace it, 2years old at present 3-4years to go until I need to do that.

[Rebotco]

If you get the flexible type of solar panel, these stick directly on the roof and are only 3 or 4 mm thick. They do not interfere with the centre ropes and can even be walked over. Probably a bit more expensive, but IMO worth it for the elimination of hassle.

[Ricco1]

Maybe consider putting fixed (flat) panels on the front third of the boat. If you shop around you can get around 60p/ watt. OK flat isn't best but it makes for a relatively cheap installation. I have 3 x 125 watt panels fitted this way, total cost £500.00 with good controller, wire and frames, gives me all the electricity I can use, and far more.

[peterboat]

I have just ordered 800w of flexible solar it 1.5mm thick it will be glued down wind theft etc it cost 880 quid. I think 100w of solar is worth it but not at the effort that the folding stuff will cause. The other plus is it extends the life of your batteries and reduces wear on your engine and pocket, diesel will never get cheaper but the choice is yours

 

Peter

[Clifford]

I agree with the others. A small panel is only marginally useful if you are putting it away all the time. A small panel is most useful as an always-on trickle charger to keep batteries healthy when the owner isn't using the boat.

[ditchcrawler]

that's the lines of thought that I have been going down.

Much as I like the idea of solar unless circumstances or roof space change I think that the cash would be better spent on enlarging the battery bank next time I replace it, 2years old at present 3-4years to go until I need to do that.

I have two panels that I put on the roof when we leave the boat to go home. When we get back to the boat they get taken down, put in a wooden box under the tug deck until we get back to Napton, then out they come again. I did consider getting them out while moored in Bath but couldn't be bothered. Like you I use a center rope and also walk on the roof when locking. We met a hire boat today that had a panel and the chap on it said he continually caught the center rope on the corners even though it had chamfered edged fixings.

[bottle]

Julian (Loddon)

 

I will make it simple for you with your usage of your boat then the benefit of solar panels will be minimal

 

Maybe a larger bank (amp.hrs) would help but even that is doubtful because for 11/12^ths of the year you have a shoreline.

 

If your start battery is not being maintained during that time, on shoreline, then a small solar panel for start battery would help.

 

ps. I have pole rack and poles, plank etc. and two 100 watt panels on a tilt and swivel mount behind my centre point and do not have problems with my centre lines (two)

[GUMPY]

Julian (Loddon)

 

I will make it simple for you with your usage of your boat then the benefit of solar panels will be minimal

 

Maybe a larger bank (amp.hrs) would help but even that is doubtful because for 11/12^ths of the year you have a shoreline.

 

If your start battery is not being maintained during that time, on shoreline, then a small solar panel for start battery would help.

 

ps. I have pole rack and poles, plank etc. and two 100 watt panels on a tilt and swivel mount behind my centre point and do not have problems with my centre lines (two)

Who mentioned starter batteries?

FYI the system here uses a VSR to join both starter and leisure the batteries together when the charger is on.

The system also has two alternators 90a prestolite and a 70a A127 so the VSR parrallels their output when the engine is running. I have no problems with lack of power I was just looking for a way whereby I might be able to attend boat gatherings for a few days etc without having to run my engine to keep the batteries well above 50%.

As I said earlier possibly the best idea for me is to increase the size of the bank from 3 TO 5 batteries when I next replace them even though that will mean moving their location and wont happen for a few years yet.

Edited May 16, 2014 by Loddon

[Richard10002]

I don't think anyone at a boat gathering would object to an engine being run at the appropriate times - many will be doing just that. Others will have a generator attached to the shorepower input.

 

Not worth buying solar panels for a few gatherings, and the odd day when you are neither cruising nor attached to shore power.

 

With a 400Ah bank, you could probably just about manage a couple of days without charging, and remain above 50%.

 

If you have to mess about with the battery space, it might be worth considering 4 Trojan T105 batteries, which would provide 450Ah, and would tolerate discharge below 50%. At today's price of about £430 for 4, they seem good value.

[GUMPY]

My battery space takes 3 standard size 100/125Ah batteries because of their position (Eberspacher air intake is in the same area) I have got sealed lead acid I have these

 

http://www.alpha-batteries.co.uk/marine-batteries/125-ah-xplorerleisure-battery/

 

means I never have to look at them but all charge voltages must be 14.4 or below. So the batteries will get moved to under the bed, again must be sealed and I have been considering five or six of these

 

http://www.advancedbatterysupplies.co.uk/abs100ahagmbattery

 

Just need to research them a bit more.

[peterboat]

I had AGMs on before the full tractions fitted 2008 now on friends boat still working well 6 years old

 

Peter

[bottle]

Who mentioned starter batteries?

FYI the system here uses a VSR to join both starter and leisure the batteries together when the charger is on.

The system also has two alternators 90a prestolite and a 70a A127 so the VSR parrallels their output when the engine is running. I have no problems with lack of power I was just looking for a way whereby I might be able to attend boat gatherings for a few days etc without having to run my engine to keep the batteries well above 50%.

As I said earlier possibly the best idea for me is to increase the size of the bank from 3 TO 5 batteries when I next replace them even though that will mean moving their location and wont happen for a few years yet.

 

No one, I just threw it into the mix, I did say, If.

 

Goal posts moved a little.

 

My battery space takes 3 standard size 100/125Ah batteries because of their position (Eberspacher air intake is in the same area) I have got sealed lead acid I have these

 

http://www.alpha-batteries.co.uk/marine-batteries/125-ah-xplorerleisure-battery/

 

means I never have to look at them but all charge voltages must be 14.4 or below. So the batteries will get moved to under the bed, again must be sealed and I have been considering five or six of these

 

http://www.advancedbatterysupplies.co.uk/abs100ahagmbattery

 

Just need to research them a bit more.

 

I believe this will not comply with BSS, unless you get certification from the manufacturers to say they can be fitted in said area.

Or the area is sealed from the boat and vented to the outside

 

You may wish to check with the BSS.

 

FYI. I went from 330 amp.hr @ 24v sealed leisure batteries to 330 amp.hr @ 24v deep cycle AGM. They cope much better with the same loads and the SOC stays higher. Of course the price is much higher and they will have to have a longer life, approx five years to make it worthwhile.

 

Edit: the batteries were of the same physical size but weighed 5Kg extra (each), ballast had to be moved.

Edited May 16, 2014 by bottle