Ideas Wanted : A very simple Solar Panel Set Up

[creeksailor]

Planning to spend a few one and two week cruises onboard this coming season. This will involve quite a bit of night sailing, so I am looking for the simplest non permanent solution to top up a 12 v 55ah battery that will power the nav lights and not set fire to the boat. Any usefull suggestions?

 

[VicS]

You need to estimate your daily power consumption in Ah

Then choose a panel that will typically provide at least this much power ( in Ah)
daily.

You should increase your battery capacity to ensure you can go for a couple of days or so without significant charging and without running the battery below 50%.

If the panel exceeds 1 watt per 10 Ah of battery capacity or exceeds 10 watts .... it will! ... you should fit a regulator

 

[jordanbasset]

Hi, you have a fairly small battery and if you only want a temporary solution can you charge it from your engine (if you have one). Couple of gallons of fuel would work out a lot cheaper.

 

[VicS]

A useful suggestion :

replace as many light bulbs as possible with LED ones.. interior lights and Nav lights


Dont try to use one of those Peltier element coolboxes.

 

[VicS]

Hi, you have a fairly small battery and if you only want a temporary solution can you charge it from your engine (if you have one). Couple of gallons of fuel would work out a lot cheaper.

Only a seagull it would seem!

 

[Tranona]

Hi, you have a fairly small battery and if you only want a temporary solution can you charge it from your engine (if you have one). Couple of gallons of fuel would work out a lot cheaper.

Suggest you have a look at tthe OP's blog then you will see why he is enquiring after solar panels.

 

[creeksailor]

Thanks for responses. Firstly forgive my ignorance of ah calcs. Ive manged thus far being able to take the battery home if needed but as I will be away for quite some time I want the lights to work if taking a night tide one week in.
I guess usage would be two or three hours at most, for five nights over ten day period. A panel that essentially will give power for two 5w side lights and a 5w stern light.
Not keen on the idea of running the Seagull to do a charging job as bullet proof and antique it is does not have the facility. Would have to be a passive solar charge.

 

[VicS]

Very low power your lights!

however three at 5 watts = 15 watts .

15 watts at 12 volts = 15 ÷ 12 = 1.25 amps

1.25 amps for three hours = 3 x 1.25 = 3.75 Ah per night


If you have a 55 Ah battery you can use about half of that 55 ÷ 2 = 27.5 Ah.

So you could happily last for 27.5 ÷ 3.75 = 7.33 nights. call it 7 nights.

Conclusion then is that you could sail for three hours every night for 7 nights and still be within the 50% usable capacity of your battery.

But it is better for the battery to keep it topped up.

I have a 5 watt Spectralite semiflexible panel mounted permanently it gives me a max of 300mA (0.3 amp).

Suppose I get that for 5 hours each day on average I will get 5 x 0.3 = 1.5 Ah
put back into the battery every day.

To replace 3.75 Ah every day I would need a solar panel rather more than twice the size.

One of Maplins 13 watt Solar Brief cases http://www.maplin.co.uk/13w-solar-briefcase-99760 would do rather nicely especially as a non permanent installation. They come up at special prices from time to time too. http://www.sunshinesolar.co.uk/khxc/gbu0-prodshow/SS936A.html

You could reduce your power consumption by fitting LED "bulbs" into your lights

LEDs with a power consumption of only 1.3 watts would be equivalent of 5 watt bulbs and still give you a visible range of 1 nautical mile for the side lights and 2 nautical miles for the stern light

 

[Rigger Mortice]

If you also think about getting rid of those two sidelights and installing a bicolour instead, you will reduce consumption by one third.

PS I like the boat!

 

[Tranona]

I would be inclined to up the battery capacity to 85 and use a flexible 10w solar panel to top up.

 

[Puggy]

VicS has done all the correct calculations.

All I would say is buy the largest flexible solar panel you can afford as the rated outputs are very optimistic (orientation and direct sunshine are key to decent output) and you wont see anything like that in reality. Buy a regulator so that you have no danger of over charging the battery, but also most come with battery condition lights to tell you how much charge you have in the battery. Avoid buying from marine chandlers as the same kit is available from outdoor/caravan vendors for far less money.

On my last boat (Beneteau First 210) I also carried a small Honda petrol generator and 240v battery charger for when consumption overtook sunshine: fire it up and leave it running in the cockpit. leave for the pub. It runs out of fuel in 4 hours about the time you stagger back. I have to say I only did this at anchor so that a) it didn't annoy the neighbours and b) if it caught fire, it didn't annoy the neighbours...

 

[creeksailor]

You chaps are brill! some good info.. Thanks for working out the calcs Vics - much apreciated.
I'll consider if its worth me upgrading the battery to 85AH, but then that would also mean a larger, heavier unit? Which I'd like to avoid unless it became necessary.

 

[V1701]

I've had three inexpensive solar panels from ebay, two aluminium framed and one semi flexible, and PWM regulators also from ebay, all very reasonable and all work fine. IMO stuff fron Maplin's is overpriced for what you get...

 

[TQA]

Like everyone else says go LED.

But given the unreliability of British sunshine I wonder about relying on solar even with a good 40 watt panel giving you around 2 amps.

On the other hand a dinky suitcase generator and a Halfords battery charger will get you 10 to 15 amps for less than £100

 

[simonfraser]

As said the solar panel wil have to face the sun, assuming u r sailing during the day thats gona b tricky.
I have 14W on each side of my cabin and get 1.5A max when sailing in summer.

 

[William_H]

Solar

from looking at OP blog the problem will be location and mounting of the panel. This will dictate the size that an realistically be fitted. I would think in terms of 10w on a pole with facility to direct it at the sun (south) and adjust the elevation to get max power. Mount it near the stern but out of the way. If you choose to mount a panel on the roof (fixed) you will need a lot more power to allow for less than optimum pointing.
I would not rush to buy a regulator if it is only to be used while you are on hand and using power from the battery regularly. Regulators are for stopping overcharge of battery and this is not likely in your case especially with 10 or even 20w.

As Vic says you will find going LED more cost effective to the end aim. Purpose built LED side nav lights are very visible, legal and light on current. Don't even think of mast top tricolor, no one will be looking up mast height for your boat or lights. And of course you don't want mast wiring. I think a stern light is OK with LED replacement.
With LED nav lights and interior lights you could almost go for dry cells to power them although now you have battery you may as well go down that road.
http://www.banggood.com/Wholesale-Led-Bulbs-c-1627.html the 48LEd panel is a dilly for internal lighting just stick it on the inside of the roof.
I like your idea of mud cruising. I did try it for one night last year but alas I get bored too easily. good luck olewill

 

[uxb]

On my last boat (Beneteau First 210) I also carried a small Honda petrol generator and 240v battery charger for when consumption overtook sunshine: fire it up and leave it running in the cockpit. leave for the pub. It runs out of fuel in 4 hours about the time you stagger back. I have to say I only did this at anchor so that a) it didn't annoy the neighbours and b) if it caught fire, it didn't annoy the neighbours...

I like your way of thinking!

 

[Tintin]

I got this 60w solar kit from Maplin in the summer for £200. It is actually 4 x 15w panels, and it comes with a regulator and a load of cables.

It means I can just lay out the panels to suit, tieing them on so they don't go over the side.

I can also use one to four, which I think makes a great system for top-up.

Frankly I am impressed with the value for money.

 

[creeksailor]

Ok many thanks.
Found a couple of decent looking 10 watt panels, there are cheaper versions at half the price on ebay but these are made with a frame, up to 28mm thick, that could interfere with furling lines.
These two panels seem to be suitable, mainly because they are semi flexible and thin.: One from Ebayhttp://www.ebay.co.uk/itm/Sunshine-Semi-Flexible-Solar-Panel-10-Watt-12V-/260803185194?pt=UK_Gadgets&hash=item3cb914ca2a and one from Nasa Marine http://www.nasamarine.com/proddetail.php?prod=Solarpanel&cat=23 There is not much in the price between the two, so it may be worth buying the Nasa Marine product.

 

[Fantasie 19]

Ok many thanks.
Found a couple of decent looking 10 watt panels, there are cheaper versions at half the price on ebay but these are made with a frame, up to 28mm thick, that could interfere with furling lines.
These two panels seem to be suitable, mainly because they are semi flexible and thin.: One from Ebayhttp://www.ebay.co.uk/itm/Sunshine-Semi-Flexible-Solar-Panel-10-Watt-12V-/260803185194?pt=UK_Gadgets&hash=item3cb914ca2a and one from Nasa Marine http://www.nasamarine.com/proddetail.php?prod=Solarpanel&cat=23 There is not much in the price between the two, so it may be worth buying the Nasa Marine product.

I like the NASA web page.. "For higher solar panel to battery ratios a charge controller may be advisable particularly in the unlikely event of the UK having a long hot summer."