Solar power

[jeffbroadslover]

Been having a look on the BB webcam and noticed that BB seem to have invested in quite a bit of cash in fitting solar panels on quite a few boats over the winter.

Anybody know how many of their boats have now got solar panels?

 

Jeff

[Hylander]

I cannot answer for BB but when we had our boat, the solar panel quite a large one saved us £s on fuel ,   we use to run our engine to recharge the batteries but no need with a solar panel.   As soon as it is light it is charging up everything.  An absolute boon.   Be glad when all boats have this facility.  No more red faces with flat batteries.

[Vaughan]

We did a lot of research into this in France (where the sun shines) but there are still not many hire boats that have them. A modern boat with all the goodies, and two fridges, will use around 190 amp hours a day and solar panels can't contribute much to that. But at least a hire boat is having a good run every day, so that makes up for it.

The real problem with flat batteries is that the installers of all the "bolt on goodies" have not done the calculation between ;

The amount of current that is going to be used in a day -

The number of batteries needed to supply this - remember that a battery can only be discharged to half its capacity, so a 100AH battery will only give you 50AH usable (unless you want to wreck it).

The alternator capacity needed to put back all these amp hours in about 4 hours running. This is a crucial calculation if you don't want to overcharge the batteries.

On hire craft there is also the eternal problem of the hirers' children jumping up and down on them, or maybe someone dumping a bicycle on them. In other words they are not "hirer-proof".

On a private boat though, they are a very good idea, if for no other reason than keeping the batteries topped up at all times when left on a mooring and thus avoiding "sulfation" of the battery plates.

Yes, there are modern "whizz bang" space-age batteries these days but the principles of the installation are still the same.

[LondonRascal]

Don't expect too much out of a Solar panel -  even if you have an MPPT charge controller, because unlike on a house, they lay flat on the cabin tops of a boat so don't maximize the suns light as it passes in its arc during the day.  There is a lot of information out there on how they work, how best to install and wire them and with Google much of this can be obtained for free.  I personally like reading up and learning about new things anyway.

The sort that are put on the new builds from Richardson's are going to do very little in the general scheme of things,  but on a bright day may provide enough amps to 'cancel out' those used from running the Fridge.

The biggest two drains on batteries on hire boats are the heating and fridge - especially as so many people take over a boat and the first thing done is 'turn the fridge up to max'.  What may be more effective on a private boat is a duel system whereby you have solar and wind power generation - especially if you more where shore power is not provided, this would keep your batteries topped up and cover you from the running of the bilge pump for usually if it is not sunny there is some wind about and if not windy it is sunny.

[Hylander]

I have to say that our solar panel kept our batteries topped up including running a 22 inch LED TV . Saved a fortune on,diesel.

 

 

[Siddy]

Having been on a RC45 and broadway a few times I must say the solar panels in Sept have held there own and charged the batteries seeing the LEDs go green on the dash - ok we got caught out on little Wroxham green mooring last year no hot water in the evening as I didn't run the engine to charge the batteries,

Now Commodore didn't have panels but running the heating and tv on a evening it seem to last. £90 for 6 days fuel.

Started looking at panels for the house last week but after going a energy course looks like I've missed the buyin deals.

[MauriceMynah]

I'm terrified that my solar panals will be stolen, so I only put them out at night.

See, I'm not stupid you know.

[Hockham Admiral]

14 minutes ago, MauriceMynah said:

I'm terrified that my solar panals will be stolen, so I only put them out at night.

See, I'm not stupid you know.

I didn't know we were in the Jokes section, John!           

[riyadhcrew]

I just looked on the Internet at "Smart Lithium Batteries" for marine installations. They are awesome. If Clive has replaced the lead acid with the same size and ammount of LI batteries, the capacity will be fantastic.

I have had Carousel a couple of times and never had a problem with the batteries at all.

[Regulo]

I'm not falling for all this hype - I'm fitting lunar panels instead.

[Regulo]

My mate Dave has just pointed out a flaw in my lunar panels idea. What happens if the moon isn't out? Well, I've given it some thought, and reckon I've got the answer. I connect a 500W inverter, and run a 300W floodlight out of the cabin window to shine on the panel. That should then generate about 4 Amps of current! I'm not as daft as you all think I am.

[LondonRascal]

I think the type of batteries in Commodore are Lithium Iron. The lithium iron phosphate (LiFePO4) batteries are also called LFP battery.

If I were going to use Lithium cells on a boat, certainly I would opt for Lithium Iron technology due to the safety aspect since lithium iron phosphate cells are much harder to ignite in the event of mishandling (especially during charging) and are more robust generally than the sort of Lithium cells your find in laptops, phones or even those used in the likes of model aircraft/quad copters etc.

They cost a lot though - though that depends on whom and where you purchase them, their benefit however is they are fully sealed, they can be discharged fully and recharged fully without any issues or damage unlike any lead based batteries, they are lighter and more energy dense and they can  be fully or partially discharged  many thousands of times, meaning the batteries should last the life of the boat.

Here is a handy guide to Lithium for boats: https://www.victronenergy.com/blog/2015/03/30/batteries-lithium-ion-vs-agm/

Solar panels - it is all about amps and this is why they are fine for 'topping off' a battery, but the average boat simply does not have the available area to be able to run anything much from solar.  For example, if the solar panel is rated at 175 watts (so that will be a biggun)  the maximum power voltage, (Vmp) is 23.6 volts, then you would calculate the current as 175 watts divided by 23.6 volts, which is equal to 7.42 amps. This is current produced by the solar panel at full power.

So 175 Watt panel will - in the best possible conditions - produce just over 7.5 amps.  Now compare this to your boats Alternator which might be putting out 60amps to 90amps.  This is why I made reference to a fridge and its power use being 'cancelled out' by the solar panel (on a good, bright long sunny day) because a fridge will draw about as much amps as the panel can feed back in to the system. 

Things like lighting, a TV etc use less so overall having a solar panel is no bad thing, but if you've got two domestic batteries which have been used overnight to 50% capacity, it is going to take a very long time in direct sunshine for your panel to provide any noticeable charge to them compared with running the engine.

[ExUserGone]

2 hours ago, Regulo said:

My mate Dave has just pointed out a flaw in my lunar panels idea. What happens if the moon isn't out? Well, I've given it some thought, and reckon I've got the answer. I connect a 500W inverter, and run a 300W floodlight out of the cabin window to shine on the panel. That should then generate about 4 Amps of current! I'm not as daft as you all think I am.

I like a dark sky when I'm on the boat so I've painted a 1000 watt spotlight black so I can shine it from the roof to make it darker, don't moor beside me or your lunar panel won't work at all!

[JawsOrca]

I'd like to put solar panels on Orca's hard top roof which is huge. I'd like them to just keep both batteries topped up when not in use. We have a 110amp leisure battery and a 70amp engine battery. At rest Orca is a stern drive boat with no leaks (ok well just a little rainwater) the pumps should never run (and they are massive if they do, so nothing has much chance at keeping the batteries charged if they do!). So output should just be natural discharge from the battery. Can anyone suggest what panel we should get. I'd like it stop charging if the batteries are charged i.e be completely safe and ideally not requiring us to disconnect if the engine is running.  

[LondonRascal]

Alan, since your battery bank is small and since all you want to do is make sure it was always topped off you can get a simple install pretty cheaply.

If you are happy with not having a flush fit panel you can walk over,  something like this might be an idea as it is all 'ready to go' and reasonably priced and has some favorable reviews.

http://www.amazon.co.uk/dp/B009FP2R2K 

 

 

[JawsOrca]

58 minutes ago, LondonRascal said:

Alan, since your battery bank is small and since all you want to do is make sure it was always topped off you can get a simple install pretty cheaply.

If you are happy with not having a flush fit panel you can walk over,  something like this might be an idea as it is all 'ready to go' and reasonably priced and has some favorable reviews.

http://www.amazon.co.uk/dp/B009FP2R2K 

 

 

 Robin, how are you working out how big the panel should be?? We do have a big area so if we can make more use of it then I'm keen to do that. (Although I guess as our draw is so small there's no point??).

[LondonRascal]

I was basing size on need - simply put; you don’t have a large battery bank and I am not too sure if you have sure power at your mooring (or indeed on your boat) it would be a good idea to have some sort of charge going into the batteries when not about if nothing more to keep them in tip top shape.

If you got a larger panel that covered more of your wheelhouse roof, you’d get a larger amperage output – faster charge of batteries but...Would that really be needed? It would not be a great help when you’re not at the boat as once the battery is full you just want it to maintain voltage.  

Having said this, you have spoken of the want to get a bow thruster – the best practice is to have a separate battery for this job and naturally this battery also needs to be kept charged to ensure the bow thruster works when you need it so that will take you to three batteries – might you in time consider an upgrade to your domestic supply to two batteries? If so this might influence a large more expensive panel which would provide additional amperage to recharge when the boat is left.

It really comes down to need and cost – as you will notice as you get into the larger panels so the cost quickly rise so the old saying ‘you pays your money you makes your choice’...

[JawsOrca]

OK  Robin. I think at present I'd like to at least keep the engine battery topped up so she can be started without worry if left for a bit (although it seems ok without at present). Yes it would be good to keep the domestic in good running order too. I don't think we have any plans to add another domestic at the moment and it's managing well. The bow thruster will probably happen later in the year so we can always add another panel later I'd guess. 

Any stories of these things causing problems with overcharging though?  

 

[BroadAmbition]

Er, our present solar panel will soon be up for sale . . . .

Griff

[JawsOrca]

1 minute ago, BroadAmbition said:

Er, our present solar panel will soon be up for sale . . . .

Griff

Does it not work Griff? 

[LondonRascal]

Alan, that is what the charge controller does - it will do three things in the simplest form stop the batteries discharging into the panel when there is no sun (at night), stop the panel providing voltage to the batteries once they are full and meaning the panel is not damaged when the engine is running and the alternator is providing power to the batteries.

The smaller panel as I linked to could be easily wired to provide charge for your starter and domestic battery just as on Broad Ambition our panel used to be just to top off the starter battery but now provides charge to the 5 domestic batteries.

And, the panel that is currently on Broad Ambition does work very well - the problem is you don;t tend to walk about or have need for things to be placed on your wheelhouse roof on Orca, but on Broad Ambition we loose a bunch of space that is a real 'no tread' area - so we are wanting to go with a 150w 'flush fit' panel that would take being stood upon or things like tackle boxes being put on without fear the glass panel with break.