Solar kit for boat

daveville30

Hi I have a boat and want to install a solar panel to keep the batterys topped up.ive 2 12v batterys linked together to give 24v to the starter.ive seen a few kits on e bay with a charge controller what size kit and would it need to be a 24v solar panel?

~300W domestic panel 60Cell far better value for money than weekend warrior little panels.

Morningstar PWM charge controller will out run any other MPPT with a 60 cell (~32Vmp) to 24v configuration.

Here's one I made earlier (well that's MPPT because it was a good deal)

daveville30

Sir Liamalot wrote: »

~300W domestic panel 60Cell far better value for money than weekend warrior little panels.

Morningstar PWM charge controller will out run any other MPPT with a 60 cell (~32Voc) to 24v configuration.

Here's one I made earlier (well that's MPPT because it was a good deal)

I'm not hoping to run things just keep them topped up.i dont really understand what my requirements would be. the solar panels are in watts and the charge controllers are in amps.would a 50 watt panel and 30 amp controller be ok for 24v batteries?

Sure but a 50W, "12 volt" panel is almost €100 and not very efficient (cell to battery voltage mismatch link).

A 300W panel for a house is perfect for 24V is ~€120.

Pictured system doesn't run anything either. It's just for maintenance/storage.

freddyuk

As the batteries will be fully charged when you leave the boat all you need is a trickle charge. I use a 30watt panel which sits nicely on the radar arch and is unobtrusive. 2 of these would give you 24v. No point in a whopping great 300w panel for this purpose.?? A decent PWM controller rated at 5 or 10 amps is more than enough and easy to come by.

If it costs pretty much the same why not have 10x the power?

If you click on the link you're advising to invest in a panel that's 17% redundant or 2 x 30W = 50W PWM.
1 x 60 cell at 24v PWM = all usable cells with just enough overhead for installation losses.

Shore power is expensive and diesel is worse outtov port.

There is only one genuine manufacturer of solar charge controllers. Specific gravity is quite the teller.

daveville30

freddyuk wrote: »

As the batteries will be fully charged when you leave the boat all you need is a trickle charge. I use a 30watt panel which sits nicely on the radar arch and is unobtrusive. 2 of these would give you 24v. No point in a whopping great 300w panel for this purpose.?? A decent PWM controller rated at 5 or 10 amps is more than enough and easy to come by.

I'd rather 1 panel or could I hook up to one battery that should charge the other one?I'm thinking of a 50 or 70 watt panel

unkel

I'm with Sir Liamalot on this. If you have the space and you don't mind a fixed (non flexible) panel, get a full size 300W panel. Far, far cheaper per watt than anything else and you could even just connect it via a €10 controller to your two 12V batteries in series for a very cheap system. Full size panels also hold their value well if you buy it cheaply, so if you decide to sell it on at a later date, you will have lost very little

daveville30

unkel wrote: »

I'm with Sir Liamalot on this. If you have the space and you don't mind a fixed (non flexible) panel, get a full size 300W panel. Far, far cheaper per watt than anything else and you could even just connect it via a €10 controller to your two 12V batteries in series for a very cheap system. Full size panels also hold their value well if you buy it cheaply, so if you decide to sell it on at a later date, you will have lost very little

If I'm only trickle charging the batterys would a 300w not be to much where would the extra power go to.im not to clued up on solar

unkel

The "extra power" would go nowhere. The charge controller will not let the battery go over a certain voltage. The good thing with a big panel too, is that you can double your batteries to 4 of them. Even 8 of them. And the big panel will easily keep them topped up all year, even in winter.

Doesn't have to be 300Wp that's just where the market is at.
60cell panel ~32Vmp is ideal.
I have a 240Wp flavours...bit old now

freddyuk

I'm going to ask what size boat are we talking about? Does it have the space for a 300w panel?

Arah sher they work outboard or even hinged off the hull. Oil rigs put them vertically to keep the bird poo off them and they capture photons reflected off the water.
If it was 300 watt one could lose 50% efficiency and still get better watt per € than 2 x 80w "12 volt" jobbers

a 60cell 250W has the equivalent power of 2 x 150Ws 36 cells on PWM in a ~20% smaller package

daveville30

28 ft boat I could put a panel on top of the wheelhouse but I dont want to take all the space up the mast is there aswell

Avoid shadows.

When I'm fitting sailboats and the client needs 300Wp I fit 600Wp; 2 x 300Wp, one either side of the prevailing shade on individual controllers.

n97 mini

In the depths of winter (when you're not using your boat) don't forget the output from a solar panel will be severely limited. i.e. get the 300w panel!

daveville30

I'll still be doing the same routine in the winter go down every couple of days start her up to charge the batterys.id like to be able to leave her a week though and have full charge on them

freddyuk

So there you go..... a 300wp panel is nuts for you. I have a 8m boat now (but cannot get to it) and have fitted a 150wp panel onto the "house" battery as I am a solar nut and it was available. It takes up roof space which is supposed to be for sunbathing (ha, ha) but is more than enough. It clips on the roof rails so can be easily removed for cleaning etc. The engine battery is sitting there quite happy for some weeks but can be charged from the mains if required. Good batteries will not die after a few weeks if there is no load on them. In fact to keep Lead Acid batteries long term they need a mains charge regularly but solar can never do this so its a compromise.
At home, then the more solar panels the better as the loads are far higher and surplus is rare but not on a boat it is wasted and intrusive. Space is at a premium so design a system that works for your boat not slap on the biggest solar panel possible based on the home based system as you will not be able to store the power. If you are living aboard then more the merrier.... the fridge will need 100w + alone.

freddyuk

freddyuk wrote: »

In fact to keep Lead Acid batteries long term they need a mains charge regularly but solar can never do this so its a compromise.

How odd. Living full time in a vehicle for a decade I've found the inverse to be true.
If defining fully charged as 1.275 SG


I guess I must be doing it wrong.



I wouldn't advise abandoning batteries to their own devices without input.


It's not about panel size, it's about not getting ripped off.
Last time I checked a 150W panel was €200 and a 300W panel was €120.


Why pay more for less?

freddyuk

I have lots of time for you but a boat is different. Space is a premium. If you just go out and do some fishing for the day then you will not be using much battery power and when you get back the battery/ies are fully charged so just need a trickle until next time you go out. A van roof is dead space but a boat roof is possibly multi use so having it taken up with a solar panel which will be in "potential" for much of the time is not great efficiency. A house roof is 100% dead space so fill your boots there as it will not matter.I feel the OP is looking for a solution that does not need overkill.
But yes as regards solar in general get as much as you can .... I totally agree.

Same goes Freddy. And I you.

Merlin Smartbank £20 best split charge relay driver you can get. It'll add years your engine battery life through your already fitted solar.

Domestic panels are dominating 2 x 12volters...price and performance. hang 'em off the stern, ballast to the deck when ashore...I just don't understand why pay a premium for a small output. Plenty of power to feed efficiency losses put them in the hold when underway if they're fouling the rigging.









If you need the power; double up, you can't have the same shadow both sides of the vessel.

And yes I know they're all 12 volt panels in photos
That's what I mean by outboard...mechanical principles are transferable.

daveville30

I'm still none the wiser I cant have a big panel I need something for on top of wheelhouse.if I buy a 50 or 70 watt panel would it need to be 24volt or are they all 12v panels

daveville30

I'm still none the wiser I cant have a big panel I need something for on top of wheelhouse.if I buy a 50 or 70 watt panel would it need to be 24volt or are they all 12v panels

Alkers

Sir Liamalot wrote: »

Same goes Freddy. And I you.

Merlin Smartbank £20 best split charge relay driver you can get. It'll add years your engine battery life through your already fitted solar.

Domestic panels are dominating 2 x 12volters...price and performance. hang 'em off the stern, ballast to the deck when ashore...I just don't understand why pay a premium for a small output. Plenty of power to feed efficiency losses put them in the hold when underway if they're fouling the rigging.









If you need the power; double up, you can't have the same shadow both sides of the vessel.

That's all well and good for a cruiser or sheltered sailing but that panel is going to take a battering offshore and cause some serious windage if racing.

Maybe a thin or flexible panel would fit without getting in the way, admittedly will be higher price per W but you only need as much as you need ! Can you post a pic op?

daveville30

Same boat and mast set up as mine. Only I have liferings epirb ect

Flexible panels aren't UV stable...mad isn't it. 3-7 year lifespan depending on brand. Twice the cost.

daveville30

daveville30 wrote: »

I need something for on top of wheelhouse.if I buy a 50 or 70 watt panel would it need to be 24volt or are they all 12v panels

You need at least 60 series solar cells to charge 24v.


The small ones are usually 36 cell. These are called 12v but they're more suitable for 16v.

daveville30

60 cells per panel?

It doesn't matter if it's one or two panels as long as there's 60 or more cells.

daveville30

Thanks.them charge controllers come in different amps 10 20 ect what would you recommend for 24v

daveville30

Would this do the job

quentingargan

If you want some small panels, Victron does a lot of boat equipment - also charge controllers. There are 100w panels out there, but you need two of them to get up to over 24v. If watts per € isn't the issue and you want small panels for aesthetic reasons look here. You could put two 20w panels in series to get your 24v.

daveville30

daveville30 wrote: »

Would this do the job

Looks like a 12v panel, dunno it's a picture not a datasheet and the charge controller is junk.


Here's a much better one

quentingargan wrote: »

If you want some small panels, Victron does a lot of boat equipment - also charge controllers.

With all due respect Q that doesn't mean they are any good.
Their chargers are lemons. They don't believe in remote temperature compensation for them either. They're built from second rate semi's and components and their failure rate is high by standards.


All they have is pricepoint and marketing. They make better pdfs than hardware and they're spending all the R&D money on advertising and giving away janky products to youtube content makers. :rolleyes:


MorningStar are the best. So bulletproof I only buy used ones and I've never had a problem with them.


Victron won't do this in a month of Sundays.




They're costing users battery life longevity for an insubstantial saving.

daveville30

Would a 12v panel not be alright if I hooked it up to one battery it should charge the other one?

Not even if they were parallel

daveville30

Ah no.would two 12 volt panels give me 24.its not a weekend boat so it be getting plenty of use

2 x "12 volt" panels will give you about 36V...a lot of wasted power on PWM. Some advise going MPPT to "fix this". I advise using 60 cell panels and PWM, far less expensive and more efficient.
If you intend to use it a lot don't get a small array.

Over 100W total will start being useful for power on demand.

If it's a liveaboard 100W for the fridge and 150W for the everything else I would consider minimum.

freddyuk

It would be helpful to know what boat we are talking about. I already asked this save us going round in circles.....?

quentingargan

Sir Liamalot wrote: »

They don't believe in remote temperature compensation for them either.

Wide range of temperature sensors here. They aren't included with charge controllers because many kits have other GX controllers or other components where this is managed, or increasingly use Li-ion which has its own control. But for lead acid, there is a choice of wired or bluetooth temperature sensing.

daveville30

freddyuk wrote: »

It would be helpful to know what boat we are talking about. I already asked this save us going round in circles.....?

Theres a picture on the thread

freddyuk

freddyuk wrote: »

It would be helpful to know what boat we are talking about. I already asked this save us going round in circles.....?

Clicky

quentingargan wrote: »

Wide range of temperature sensors here. They aren't included with charge controllers because many kits have other GX controllers or other components where this is managed, or increasingly use Li-ion which has its own control. But for lead acid, there is a choice of wired or bluetooth temperature sensing.

You're kindof reinforcing my point Q. Their small solar charge controllers do not have remote temp sensing. They measure their own heat sinks not the battery.


I can fabricate MS temp sensors with €0.50 thermistors.


I have never seen a Victron charge a battery further than 1.265 specific gravity. They rework them to add bluetooth but they still can't charge a battery right. :rolleyes:


Li-ion is not competitive. Explaination here.

They simply do not use their own products.
For instance the BMV:

Too small to read without faddling.
17 button presses to turn the backlight on and off.
It's a 52mm gauge...automotive standard...Do you not think a blue light in a dashboard is very distracting...headlamp paranioa.
It doesn't read greater than 100%...inaccurate, yet it keeps charging.
The Shunt has two positive terminals..terrible idea.
It is wired on UTP cable...is this durable and vibration resilient?

Chargers with a claimed 98% efficiency run between 60% and decimal efficiency.

Junk. Paying for a name and not much else.
The inverters are not bad. The Combis I won't go near.

daveville30

Sir Liamalot wrote: »

2 x "12 volt" panels will give you about 36V...a lot of wasted power on PWM. Some advise going MPPT to "fix this". I advise using 60 cell panels and PWM, far less expensive and more efficient.
If you intend to use it a lot don't get a small array.

Over 100W total will start being useful for power on demand.

If it's a liveaboard 100W for the fridge and 150W for the everything else I would consider minimum.

Sorry what's pwm and mppt?

freddyuk

daveville30 wrote: »

Theres a picture on the thread

Got it! Sorry.
Here is mine. 30w 0n radar arch. Victron controller at 5amps. Does the job fine. You can get 24v panels but will be expensive. 2 x 30w would be cheaper.[IMG][/img]

daveville30

No picture there.is yours charging 24v?

daveville30

daveville30 wrote: »

Sorry what's pwm and mppt?

Pulse width modulation is a simple topography that cannot use any voltage above the battery holding voltage. Cheap and cheerful, reliable.

Maximum power point tracking is a more complex and expensive technology that compensates for panel to battery mismatch, installer laziness and makes domestic panels accessable to 12v installations.
In general it's 15% better than PWM when using 18V panels on 12v batteries or 36v panels on 24v batteries.
It does enable the use of larger arrays through higher usable input voltages and current limiting.


PWM is better than MPPT when using 30V panels on 24v batteries.


PWM is adequate for your low demand needs, it's far more affordable.

freddyuk wrote: »

Victron controller at 5amps. Does the job fine.

Have you ever measured your specific gravity Freddy or how have you ascertained this?

freddyuk

I can only check the voltage as its a sealed battery for a boat!!

freddyuk

daveville30 wrote: »

No picture there.is yours charging 24v?

Image won't attach. This is 12v. As the instruments are all 12v that is fine.

freddyuk

freddyuk wrote: »

I can only check the voltage as its a sealed battery for a boat!!

So not evidence that the charger works as it should then.

Try it on a flooded or open yer glued caps and get back to us please...or maybe hold back on unfounded claims?

quentingargan

Sir Liamalot wrote: »

So not evidence that the charger works as it should then.

Try it on a flooded or open yer glued caps and get back to us please...or maybe hold back on unfounded claims?

To be fair, a controller can only read voltage, current and temperature, and do what it is told in its settings... hold the voltage at equalisation, bulk, or float for x minutes. It doesn't measure battery acidity which is really a measure of what the battery does under those conditions.

Disagree MorningStar work perfectly. And do 100% rated. My Victron 15A lemon charger only does 12.5A (after first 5 minutes..temp derating)

As I've mentioned Victron don't measure temperature...they just claim to.
To be fair to be fair Victron are costing years of battery service through negligent algorithm. They rely on people to believe the marketing and not test the outcome. It works very well for them.
The small inverter manuals don't even tell you how to properly earth them because that would look too complicated to protect users from electrocution....just don't bother is the message.

It's simple to charge a battery. Absorb until return amps = 0.