Battery banks and solar panels. Please Help

[christophert]

Hi all, hope everyone is well. 

I'm trying to make sense of what I need to make my home sustainable out of a marina for part of the year.  I'm going to have new batteries. Previously having two 110 amp leisure batteries,  I'm now going to increase this to three batteries. At first I was going to have three 140 amp batteries, but decided against this, as I don't think my battery charger is 'from my understanding' not powerful enough to keep this amount of amps topped up. The battery charger in question is a WAECO  IU1512.  From my understanding, it is designed to work with one leisure and one starter battery. So, as I'm on a budget, I've decided to go for three 115 amp batteries and hope the charger will manage ok with these.

The other thing I'd really like some help with, and more than the above, is solar energy. I'm looking at putting 600 watt of solar on my boat. I'm guessing this will be enough to keep the batteries topped up. What I'm confused with is -  the panels will be the same as those that go on a house. The charge controller will be a 50 amp MPPT type, possibly Victron, but looking at cheaper models. Someone told me I have to be careful, as house solar panels throw out higher amps. I thought a charge controller converted whatever amps from solar panels to 12v. This person told me that charge controllers will not recognise what house type solar panels give out? What this person said was - Charge controllers will only recognise 12, 24 36 volts. anything in between will confuse the controller.

What I'm trying to ascertain, and unfortunately not having much luck in finding the answers, is -  

Can I use solar that is normally fitted to a house on my narrow boat? Or do I need solar specifically designed for boats?

Does it matter about the size of my battery charger regarding an increase in battery size?

I know in theory having 600 watt of solar should keep the larger battery increase trickle charged. But would like to know if the charger alone would do the job, as solar won't be fitted straight after.

I really hope someone can help answer these questions, as I'm not getting any help from Solar World or Victron. 

 

 

[rusty69]

7 minutes ago, christophert said:

Can I use solar that is normally fitted to a house on my narrow boat?

Yes, if you have a suitable controller and the panels will physically fit.

 

Will leave it to others to answer your other questions. 

Edited March 8, 2017 by rusty69

[Robbo]

Not sure what ampage your charger is, but the only issue of having a small charger on a larger battery bank is that it will take more time to charge them.   If your charging on shore power then it is no issue, but if doing via a generator then that's a different matter as you'll be wanting to charge the batteries as quickly and efficiently as possible.

The only real issue is that the charger is more powerful than your average amp consumption.

[Jambo]

Dunno what they're talking about. An MPPT controller can take any voltage array up to its limit voltage (but no more). They can usually handle an array that could potentially deliver more than their rated current no problem so there's not an issue with oversizing your array a bit in terms of amps.

What are you going for? 3 x 200W or 2 x 300W? Assuming that the panels are something like 37V panels and that Victron appears to have a 100V limit, you would have to connect 3 x 200W in parallel, but you could connect 2 x 300W in series if you wanted to.

Edited March 8, 2017 by Jambo

[Robbo]

What ever solar controller you get, get a MTTP one as these take a range of voltages from 12 to 250v (depending on models).  The voltage of the solar isn't an issue as long as it doesn't go over the MTTP controller max voltage.  Many solar panels are wired in series to increase the voltage.

avoid PWM controllers, they are not as efficient and the solar voltage is important to match the battery's. (Believe I'm right?)

 

[WotEver]

The size of the charger (within limits) has far more relevance to what your daily consumption will be rather than how big your bank is. Can you replace sufficient charge?

[christophert]

Oh My !! I didn't expect so much response in such a short time!  Thank you all. It's a shame the manufacturers being Solar World and Victron couldn't respond as quickly with such straight forward answers. What responses I have had from them has been - You need to contact a local supplier, or, refer to our manuals. Neither has been much help. There's a lot here to take in, but the consensus seems that the MPPT controller, as long as it's powerful enough, will do what it's meant to.

I'll be going for two panels, 2.85 watt each  giving 5.70 watt. If I can get 300 watt panels, times two, I'll go for that. Solar World seem to have a good reputation, and the panels can take a good hammering. Useful when going under bridges and misfits throwing boulders on at the boat.!  I'll go for a 50 amp MPPT controller, should be sufficient. Though I would like to look at alternatives to Victron as they are expensive. Any suggestions would be most appreciated.

Again, thank you for your kind support and advice. Any more information would be greatly appreciated. At least now I have a better understanding of what direction to take.   

[christophert]

40 minutes ago, WotEver said:

The size of the charger (within limits) has far more relevance to what your daily consumption will be rather than how big your bank is. Can you replace sufficient charge?

Hi, This is the question I need to look at. When in the marina, the only thing on 12 volt is the lights and fridge, and pumps. The larger battery bank will take longer to charge while in the marina, but hopefully the solar will solve this problem. 

[christophert]

53 minutes ago, Jambo said:

Dunno what they're talking about. An MPPT controller can take any voltage array up to its limit voltage (but no more). They can usually handle an array that could potentially deliver more than their rated current no problem so there's not an issue with oversizing your array a bit in terms of amps.

What are you going for? 3 x 200W or 2 x 300W? Assuming that the panels are something like 37V panels and that Victron appears to have a 100V limit, you would have to connect 3 x 200W in parallel, but you could connect 2 x 300W in series if you wanted to.

X 2 285 watt is, I believe, the biggest they do. I'm told they give out 36v per panel.  A 50 amp MPPT controller I'm hoping should be sufficient. 

[Jambo]

Should be fine. MPPT controllers that can handle large currents are expensive unfortunately. 

[Detling]

Do look at bimble solar.   http://www.bimblesolar.com/

not connected in any way but have been a customer.

The tracer units are fine and for your 600 Watts, if laid flat on the roof you can get away with a 40 Amp controller into 12 volt batteries, If you are angling the panels to track the sun then there is a slight chance it will exceed the limits for the 40Amp tracer, (brilliant day, no aircraft con trails and midday in June/July)

[Jambo]

33 minutes ago, Detling said:

Do look at bimble solar.   http://www.bimblesolar.com/

not connected in any way but have been a customer.

The tracer units are fine and for your 600 Watts, if laid flat on the roof you can get away with a 40 Amp controller into 12 volt batteries, If you are angling the panels to track the sun then there is a slight chance it will exceed the limits for the 40Amp tracer, (brilliant day, no aircraft con trails and midday in June/July)

My understanding is that it doesn't matter if it exceeds the amp limit, it will only generate up to that limit and any excess will not be utilised. But when you're generating 40A, chances are your batteries are full by mid morning so it's kind of academic. Voltage limit cannot be exceeded though. 

[Tony Brooks]

8 hours ago, christophert said:

Hi, This is the question I need to look at. When in the marina, the only thing on 12 volt is the lights and fridge, and pumps. The larger battery bank will take longer to charge while in the marina, but hopefully the solar will solve this problem. 

This tends to show a bit of misunderstanding, along with the fitting of more batteries to "make you more self sufficient".

The length of time a battery bank takes to charge depends upon how much you have taken out of it so a single battery or three batteries on a given charger will take the roughly same amount of time to charge if both have been discharged a similar amount.

A larger bank will allow you to go longer between charges but then you will have taken more out so will have to charge using the same charger for longer.

Start by doing a power audit and see if you really need three batteries and work from there but calculating the solar input is not that easy so when you are away from the marina you might have to run the engine on some days.

If your charger is a proper multi-stage marine charger and it is working well on one battery it should work just as well on three or more (within reason) as long a syou do not increase your electricity use.

 

As others often say a battery is only a bucket in which to store electricity try to put more in than you take out and it is fine, take out more than you put in and there is trouble ahead.

[Alan de Enfield]

11 hours ago, christophert said:

Does it matter about the size of my battery charger regarding an increase in battery size?

Basically the answer is NO.

You can charge a huge battery bank with a 4 amp charger - it will take a Looooooooong time, but it will charge it.

Our battery charger is far, far too small (in theory) for our battery bank, but it is only used when we are on our mooring and 'plugged in' 24/7, but, having said that, it has not been used in the last 12 months as the solar has kept the batteries charged, when we are out cruising the batteries are 'fully recharged' by the 2x 70a alternators.

Our daily usage is around 100-150Ah and with over 1000Ah of 'battery bank' we can, if needed, spend several days without running the engine or the generator. 

We have a total of 1300Ah battery bank and a 50A battery charger, according to the 'rules' it shouldn't be big enough but it fits our 'life-style' and treats the batteries very gently which is maybe why they last well (rapid, high current, charging is not good for batteries)

 

[Rickent]

9 hours ago, Jambo said:

My understanding is that it doesn't matter if it exceeds the amp limit, it will only generate up to that limit and any excess will not be utilised. But when you're generating 40A, chances are your batteries are full by mid morning so it's kind of academic. Voltage limit cannot be exceeded though. 

This is my understanding also.

[christophert]

3 hours ago, Alan de Enfield said:

Basically the answer is NO.

You can charge a huge battery bank with a 4 amp charger - it will take a Looooooooong time, but it will charge it.

Our battery charger is far, far too small (in theory) for our battery bank, but it is only used when we are on our mooring and 'plugged in' 24/7, but, having said that, it has not been used in the last 12 months as the solar has kept the batteries charged, when we are out cruising the batteries are 'fully recharged' by the 2x 70a alternators.

Our daily usage is around 100-150Ah and with over 1000Ah of 'battery bank' we can, if needed, spend several days without running the engine or the generator. 

We have a total of 1300Ah battery bank and a 50A battery charger, according to the 'rules' it shouldn't be big enough but it fits our 'life-style' and treats the batteries very gently which is maybe why they last well (rapid, high current, charging is not good for batteries)

 

Hi Alan, this is where we want to get to, and striving to do so. Your battery bank is huge! and maybe I'm worrying too much about the charger as the solar will do its part. 1300ah!! Can I ask how big are the batteries and how many you have. Also, what watt of solar powers them? 

[christophert]

4 hours ago, Tony Brooks said:

This tends to show a bit of misunderstanding, along with the fitting of more batteries to "make you more self sufficient".

The length of time a battery bank takes to charge depends upon how much you have taken out of it so a single battery or three batteries on a given charger will take the roughly same amount of time to charge if both have been discharged a similar amount.

A larger bank will allow you to go longer between charges but then you will have taken more out so will have to charge using the same charger for longer.

Start by doing a power audit and see if you really need three batteries and work from there but calculating the solar input is not that easy so when you are away from the marina you might have to run the engine on some days.

If your charger is a proper multi-stage marine charger and it is working well on one battery it should work just as well on three or more (within reason) as long a syou do not increase your electricity use.

 

As others often say a battery is only a bucket in which to store electricity try to put more in than you take out and it is fine, take out more than you put in and there is trouble ahead.

originally, I was going to go for three 140 amp batteries, six hundred watt or there about of solar power. But I'm drawing away from 140amp batteries simply because of the price, and whether the charger could cope. Maybe I'm being overly concerned regarding the charger, as the solar should do the job. I may now go for smaller batteries, 115 or 120, as the price drops significantly.  The two house panels I'm looking at generate 280 watt of solar so it'll give 560 watt total. The solarWorld panels are supposed to be quite tough and durable, and can take a knock or two. Ideal for going under bridges where small gangs may gather who like to throw stones. 

[rusty69]

1 minute ago, christophert said:

originally, I was going to go for three 140 amp batteries, six hundred watt or there about of solar power. But I'm drawing away from 140amp batteries simply because of the price, and whether the charger could cope. Maybe I'm being overly concerned regarding the charger, as the solar should do the job. I may now go for smaller batteries, 115 or 120, as the price drops significantly.  The two house panels I'm looking at generate 280 watt of solar so it'll give 560 watt total. The solarWorld panels are supposed to be quite tough and durable, and can take a knock or two. Ideal for going under bridges where small gangs may gather who like to throw stones. 

Its also worth considering going for an oversize solar controller if you intend to add more panels in the future, although it will not be as efficient if you then decide not to.

[christophert]

27 minutes ago, rusty69 said:

Its also worth considering going for an oversize solar controller if you intend to add more panels in the future, although it will not be as efficient if you then decide not to.

the prices of the controllers go up quite a bit with size. I was thinking 50 amp should be sufficient. I was thinking of Victron but they're not cheap. Wondering what other makes there are out there which has a good reputation and a reasonable price

[ditchcrawler]

At the end of the day you only need to put back what you take out plus the inefficiencies, so its all down to how much you use. 

[christophert]

14 minutes ago, ditchcrawler said:

At the end of the day you only need to put back what you take out plus the inefficiencies, so its all down to how much you use. 

My partner doesn't quite get it ! It's not a house hooked up to a never ending supply, bless her 

[Neil Smith]

Do you know the width of the panels as you might not have room to walk down the side of your roof, mine are 150w panels and there is just enough room, as for the controller fit the best you can afford as said before nimble solar do good ones.

Neil

[rusty69]

27 minutes ago, christophert said:

the prices of the controllers go up quite a bit with size. I was thinking 50 amp should be sufficient. I was thinking of Victron but they're not cheap. Wondering what other makes there are out there which has a good reputation and a reasonable price

Yes, thats the drawback. I think someone mentioned Tracer, which seems to be well priced and reliable. The more expensive options as you have mentioned are Victron,Mastervolt, Outback, Morningstar,and Midnite.

Edited March 9, 2017 by rusty69

[matty40s]

2 minutes ago, Neil Smith said:

and there is just enough room.......

 nimble solar 

☺

[Detling]

Bimble sell tracer units and they are good value up to 40 Amp,  My earlier comment about not exceeding the current by too much comes from the tracer manual which says that 10% excess wattage is fine and the controller will cap the current at its specified limit. It does say not to exceed this otherwise damage may occur.  Chances of 600 watts of panels producing 600 watts in the UK are minute/microscopic in my opinion.