Setting up my electrics for the first time, some questions - Electricty Audit

[meerlaan]

Hi everyone,

 

I have just moved onto a canal boat and am looking to update my electrics and install some solar panels. I am a newbie so really appreciate any advice you can give. I have been attempting to do an electrical audit (using a template I found online)

 

Firstly I wonder if someone could have a look over it and see if I have made any glaringly obvious mistakes?? I have done my best but I must admit I do find the electrics a little confusing !!

 

I am continually cruising and my boat is 57x10

 

I am looking at installing:
- 3x 260w or 305w solar panels (with the plan to add a fourth in the future)
- 2x 40A MPPT controllers
- Victron Multiplus Inverter/ Charger
- A monitor of some kind recommendations apreciated!

 

I will also have a Honda EU20i generator to top things up.

 

The questions which I am struggling to find answers to online are...

 

What is a good size battery bank to match this system? I have been told it's important not to go too big as it means lots of time spent trying to charge them up. Not to mention the expense.

 

Is it a good idea to get a multiplus inverter and charger or a separate inverter and charger?

 

I am thinking about purchasing a washer dryer which will need 2.1kw to run (not shown on audit) would it be acceptable / advisable to run this of my setup while the generator is running? So the batteries / inverter would only need to supply the extra bit of energy as the Honda is only rated at 1600w continuous.

 

Is there any other major bit to the system I am missing. My understanding is Batteries / Inverter / Charger / MPPT Controllers / Solar Panels / System monitor. Do I need fuses or any other bits?

 

Thanks in advace for your time.

 

Look forward to hearing your opinions. (Please be gentle I am new and still figuring it all out)

 

Martin

just figured out how to attached the file hope that works ok : http://www.martin-price.org/downloads/boat.pdf

[Loafer]

Hi Meerlaan.

 

Here's my tuppence-worth, but I'm slow of thinking and may well be beaten to the post with an answer!

 

Hi everyone,

 

I have just moved onto a canal boat and am looking to update my electrics and install some solar panels. I am a newbie so really appreciate any advice you can give. I have been attempting to do an electrical audit (using a template I found online)

 

Firstly I wonder if someone could have a look over it and see if I have made any glaringly obvious mistakes?? I have done my best but I must admit I do find the electrics a little confusing !!

 

I am continually cruising and my boat is 57x10

 

I am looking at installing:
- 3x 260w or 305w solar panels (with the plan to add a fourth in the future)
- 2x 40A MPPT controllers
- Victron Multiplus Inverter/ Charger
- A monitor of some kind recommendations apreciated!

 

I will also have a Honda EU20i generator to top things up.

 

The questions which I am struggling to find answers to online are...

 

What is a good size battery bank to match this system? I have been told it's important not to go too big as it means lots of time spent trying to charge them up. Not to mention the expense.

 

Is it a good idea to get a multiplus inverter and charger or a separate inverter and charger?

 

I am thinking about purchasing a washer dryer which will need 2.1kw to run (not shown on audit) would it be acceptable / advisable to run this of my setup while the generator is running? So the batteries / inverter would only need to supply the extra bit of energy as the Honda is only rated at 1600w continuous.

 

Is there any other major bit to the system I am missing. My understanding is Batteries / Inverter / Charger / MPPT Controllers / Solar Panels / System monitor. Do I need fuses or any other bits?

 

Thanks in advace for your time.

 

Look forward to hearing your opinions. (Please be gentle I am new and still figuring it all out)

 

Martin

just figured out how to attached the file hope that works ok : http://www.martin-price.org/downloads/boat.pdf

 

1. Where is your audit?

 

2. You shouldn't need 2 solar controllers. There is the option to wire your panels in series or parallel, with huge reduction in current. That needs further examination.

 

3. Get separate charger and inverter. My BIGGEST recommendation.

 

4. The Honda 20i is regarded as the dog's bollocks.

 

5. Running your 2.1kW washer-dryer is your biggest snag. You would need a hideously expensive 4kW inverter to run that, and it would be best used when running your engine with a 200A alternator. Forget the 2.1 kW washer-dryer. (PS it doesn't use 2.1 kW all the time, so it might be workable. Someone else will tell you it's ok!)

 

6. All wiring need a fuse, such that if there is ever a short-circuit anywhere, the fuse will blow before the wiring catches fire. That is nothing to do with the appliance, the fuse is purely to protect the cable from setting fire to your boat. Your fusing requirements are beyond the scope of my present condition!

Sorry - just spotted your audit file but won't have time to digest it tonight!

Edited March 31, 2016 by Loafer

[Loafer]

On first glance, there are a few highly contestable items in your power audit. I will attempt to be more detailed later today!

 

There are some excellent 'electrical' people on this forum - please make notes, and listen to what they say, over the next few days!

[Paul C]

Looking at the power audit, the fridge value seem a bit low, and the mobile phone recharging looks a bit high. Also, the lighting seems high - worth going for LEDs if you are liveaboard etc.

[Giant]

Welcome to the forum.

 

You say that you find the electrics confusing and aren't sure about things like whether you need fuses. If that's the case then I think you should consider very carefully whether you should be installing all this yourself. There are a lot of ways to get it wrong and end up with something that seems to work but is actually unsafe under certain conditions.

 

That said, you've had a good bash at doing a power audit and seem to grasp some of the basics.

 

Looking at your audit, one of the main issues that strikes me is that you're assuming a constant 75A charge rate from your alternator. In practice you won't get that, because as the batteries fill up the current they will accept falls. It can take a very long time to fully charge any battery. No matter how much power you have available to charge them, the current they will accept goes down and down and down the more full they get.

 

You mention wanting to run a 2.1kW load off a 1.6kW generator by boosting it with the inverter. If you want that capability, you will need the MultiPlus rather than a separate inverter & charger. That feature is called PowerAssist on the Victrons and isn't present on the standalone inverter units. I'm leaving aside the desirability of a 2.1kW washer dryer on an off grid boat for the moment.

Edited March 31, 2016 by Giant

[Tony Brooks]

I would suggest that you assume the alternator delivers half its rated output for four hours (it may be less) and any further alternator charging is ignored power audit wise. It will deliver a few amps but I doubt more than about 10 as long as the battery bank and load are reasonably matched.

 

I question your statement about an over large bank taking longer to charge. The time any bank takes to charge depends upon how much was taken out, not it's size unless it is so small you completely discharge it.

 

An over large bank is likely to have a longer life than an under sized one because the depth of discharge will be lower so tending to maximise the cyclic life - as long as the load and charging regime are well matched.

 

Much of the power audit, charging and battery bank size is based on assumptions because of too many unknown variables so you will get different opinions.

[WotEver]

What is the "Charge for storage/Ah" bit?

 

Tony

 

I question your statement about an over large bank taking longer to charge. The time any bank takes to charge depends upon how much was taken out, not it's size unless it is so small you completely discharge it.

 

An over large bank is likely to have a longer life than an under sized one because the depth of discharge will be lower so tending to maximise the cyclic life - as long as the load and charging regime are well matched.

Agreed 100%.

[WotEver]

Do I need fuses or any other bits?

This, more than anything else you have written, suggests to me that you should really get a marine electrician to do the design for you.

[meerlaan]

Thank you all for your replies, they are gratefully received ! I really value your input and opinions.

Ok so to try and comment....

2. You shouldn't need 2 solar controllers. There is the option to wire your panels in series or parallel, with huge reduction in current. That needs further examination.

I got this idea from bible solar packages, where there supply 2 controllers of 40A each instead of one 80A which is considerably more expensive, I thought is was best to the keep the current high? I welcome people opinions on this and the best kind of controller to match the panels I mentioned..

3. Get separate charger and inverter. My BIGGEST recommendation.

Can I please ask why you think this ?

Looking at the power audit, the fridge value seem a bit low, and the mobile phone recharging looks a bit high. Also, the lighting seems high - worth going for LEDs if you are liveaboard etc.

I found someone else online that said a 12v shoreline fridge uses about 1amph so that's where I got the 24amph from, what you recommend I increase it too? I think I took my phone's fast charging details which are perhaps a little ott. My lighting I had no idea how to judge, I have lights installed throughout the boat already and will in time put some new ones in so left the figure that was on the original audit. I am glad to hear this is considered over the top as hopefully mine will be less

Looking at your audit, one of the main issues that strikes me is that you're assuming a constant 75A charge rate from your alternator. In practice you won't get that, because as the batteries fill up the current they will accept falls. It can take a very long time to fully charge any battery. No matter how much power you have available to charge them, the current they will accept goes down and down and down the more full they get.

Ah ok, I didn't realise this !! I just put the number on the top of my alternator :/ how would you recommend I better represent this on the audit ? and how much would the generator put into the batteries in amps? does the engine always give more juice that the genny?

Sorry just notice Tony mentioned how to calculate my actually alternator amps. Thanks !!

This, more than anything else you have written, suggests to me that you should really get a marine electrician to do the design for you.

Yes, fair point! I have been trying to look into this, can anyone recommend someone who can install this kind of setup and give me an idea of what this might set me back?

Thanks again for everyone's help.

Martin

[Paul C]

 

 

 

 

Looking at the power audit, the fridge value seem a bit low, and the mobile phone recharging looks a bit high. Also, the lighting seems high - worth going for LEDs if you are liveaboard etc.

 

 

 

My own figures suggest 40Ah/day for a 12V fridge and 1.5Ah/day for mobile phone charging. BUT the best way to know, is to accurately measure them yourself, since they vary for different people's usage and make/model etc.

[WotEver]

 

My own figures suggest 40Ah/day for a 12V fridge...

In the many threads I have read about them that is generally the figure that is settled upon. And nearer 50Ah/day for a 240V fridge.

 

Tony

[WotEver]

 

With regard to Loafer's comment about separate charger and inverter, it's for him to justify his own comment but my own thoughts in agreement would be:

1. You can select the most suitable charger to suit your bank size, battery type, and charging regime.

2. You can select the most suitable inverter to meet the demands of your 240V loads.

3. If (when?) one of them dies the other one will continue to function.

 

Tony

[Paul C]

Another advantage is that you can wire up both the inverter and charger properly, if they're separate. Their connections are similar, but not the same. For example, if you consider the combi working as a charger off shoreline, where should the RCD be? Before the combi ie on its mains inlet. Then if you consider no shoreline connection and the combi operating as an inverter, the RCD should be after. I believe some combis include the RCD and get round this issue by internally switching it to the right place.

 

Also with the 12V connections, if its an inverter you want it isolated; and if its a battery charger you want it connected to the batteries before the isolator - similar, but not the same connection point. There's no way round this other than to compromise and put the wires in one position or another.

[WotEver]

Good points, Paul.

[Loafer]

 

Thank you all for your replies, they are gratefully received ! I really value your input and opinions.

 

Ok so to try and comment....

 

2. You shouldn't need 2 solar controllers. There is the option to wire your panels in series or parallel, with huge reduction in current. That needs further examination.

 

I got this idea from bible solar packages, where there supply 2 controllers of 40A each instead of one 80A which is considerably more expensive, I thought is was best to the keep the current high? I welcome people opinions on this and the best kind of controller to match the panels I mentioned..

 

3. Get separate charger and inverter. My BIGGEST recommendation.

 

Can I please ask why you think this ?

 

Looking at the power audit, the fridge value seem a bit low, and the mobile phone recharging looks a bit high. Also, the lighting seems high - worth going for LEDs if you are liveaboard etc.

 

I found someone else online that said a 12v shoreline fridge uses about 1amph so that's where I got the 24amph from, what you recommend I increase it too? I think I took my phone's fast charging details which are perhaps a little ott. My lighting I had no idea how to judge, I have lights installed throughout the boat already and will in time put some new ones in so left the figure that was on the original audit. I am glad to hear this is considered over the top as hopefully mine will be less

 

Looking at your audit, one of the main issues that strikes me is that you're assuming a constant 75A charge rate from your alternator. In practice you won't get that, because as the batteries fill up the current they will accept falls. It can take a very long time to fully charge any battery. No matter how much power you have available to charge them, the current they will accept goes down and down and down the more full they get.

Ah ok, I didn't realise this !! I just put the number on the top of my alternator :/ how would you recommend I better represent this on the audit ? and how much would the generator put into the batteries in amps? does the engine always give more juice that the genny?

 

Sorry just notice Tony mentioned how to calculate my actually alternator amps. Thanks !!

 

This, more than anything else you have written, suggests to me that you should really get a marine electrician to do the design for you.

 

Yes, fair point! I have been trying to look into this, can anyone recommend someone who can install this kind of setup and give me an idea of what this might set me back?

 

Thanks again for everyone's help.

 

 

 

 

Sorry for the delay - I've been a bit preoccupied.

 

If you chain together a number of panels, their voltages add up but the current remains the same as one of them.

 

EG 3X100W panels, each rated for 21V and 6A, say.

 

If you connect them in series, you get 63V and 6A. In parallel, they would be 21V at 18A. The power available is the same. You can have a mix of series and parallel, to even out all the maths, but they must be symmetrical, i.e. at chain of 3 in parallel with another chain of 3, which in this example would mean you'd get 63V at 12A.

 

If you play with your own ideas, you'll be able to determine a suitable controller. Only if MPPT though, the cheap ones just won't cut it.

 

 

As for charger/inverters, just like wot WotEver said. Two expensive independent boxes are better than one hugely expensive one, and if one of them fails, you only have to replace one of them.

 

However, if your 2.1kW washing machine is an essential requirement, then it is best to go for a 'combi' because they can add power from your batteries, to help with the washing machine load, if your generator or alternator is not quite big enough.

 

 

 

Yours is a tricky case to sort out from a distance, there are too many aspects to learn in a short time. A pet 'expert' who'll help you on the cheap, is a good idea, otherwise I'd get my head into the books.

 

I'm sorry to sound a bit negative, but liveaboard electrics from new is for the qualified or knowledgeable, sadly.

 

FUSING is one of the more important aspects here, too. All cabling needs fusing.

[Neil Smith]

I was a bit like you when i started fitting out my boat, i had a little knoledge but not enough to wire it all up safely so i was recomended a marine electrician who is also qualified in mains electric, i can give you his phone no so you can chat to him, he does a lot of work on big live aboard barges in london and is very good and reasonably priced.

 

Neil

[Jambo]

In the many threads I have read about them that is generally the figure that is settled upon. And nearer 50Ah/day for a 240V fridge.

 

Tony

 

There's no need for a 230V fridge to consume 50Ah/day. Ours uses about 180Wh of AC per day which is about 15Ah DC at 12V before you take inverter losses into account. Inverter losses will add to that 15Ah but I doubt it's that much!

[Jambo]

Not sure that it makes that much sense to go for 2x40A MPPT controllers when one would do. We have just shy of 1kW of PV and an 80A MPPT controller (Flexmax). I'd love to replace our 4x245W panels with 320W at some point which I believe would be fine because the controller simply maxes out at 80A and so it wouldn't make use of the last 25A or so available from the panels but when you're getting 80A out of your panels it's way more than you can deal with anyway. Where the extra capacity would come in handy is extending our self sufficiency out into the winter months (we're already self sufficient from about mid-March to mid-October).

 

We have 6xT105s giving us 675Ah and that's fine for our needs (we're largely 230V so have the inverter on all the time).

 

We have a combi charger/inverter (Mastervolt) and it's wonderful, never skipped a beat, but I think the advice of buying separately is sound - if our combi breaks we can't charge our batteries or provide AC but if you have separate units and one breaks you don't lose the whole lot (although I guess you increase the chances of having something break!).

[Robbo]

 

There's no need for a 230V fridge to consume 50Ah/day. Ours uses about 180Wh of AC per day which is about 15Ah DC at 12V before you take inverter losses into account. Inverter losses will add to that 15Ah but I doubt it's that much!

 

You may find your inverter uses around 20ah per day in the first place just by being on which is okay if your mainly a 240v boat, but not if just powering the fridge. Then around 80-90% conversion loss. They tend to be least efficient at low loads so it may be lower than that.

Edited April 4, 2016 by Robbo

[Jambo]

Also you might like to have a play with http://re.jrc.ec.europa.eu/pvgis/to get an idea of how much your panels would generate across the year. It's for grid-tied systems so there's a lot of uncertainty as to how much you actually get in terms of usable power when you're charging batteries but it's fun to play with.

[Jambo]

 

You may find your inverter uses around 20ah per day in the first place just by being on which is okay if your mainly a 240v boat, but not if just powering the fridge. Then around 80-90% conversion loss. They tend to be least efficient at low loads so it may be lower than that.

 

Well it also powers table lights, laptop, wifi, tablet, oven (the clock basically!), back boiler circulation pump, a projector and hot water via the immersion when it's sunny. We're toying with the idea of getting a table top freezer this summer for solar powered ice cream and cold G&Ts as well.

 

The inverter love is spread far and wide

[Alan de Enfield]

deleted

Edited April 4, 2016 by Alan de Enfield

[meerlaan]

Hi Neil, that sound like it could be a good idea, Yes I would appreciate it if you could pass me his detail please.

Interesting to hear what you say Jamno, I was wondering if that was the case with MPPT being that you just can't get any more than the figure stated, but I would think that shouldn't be a problem it will more be the less sunny days as you mention.

Can I ask what your battery setup is Jambo and what size inverter you use?

I am trying to figure out a good match, so to balance my battery bank to inverter size etc,

The washer dryer I would like is rated as follows:

Mod: WT 2670
Type: HWT02
220 - 240V~ 50Hz
2.1 - 2.4 / 1.75 - 2.05kW
13A
12V max 5W

 

I am wondering if I use a charger/ inverter while running my honda Eu20i how much will I hammer the batteries? how long will it take my to run the genny after finishing the washing/ drying to charge the batteries back up to a safe level ?

 

Also I was thinking they state 1.75kW for a wash but what wash is this on presumably a 30 is very different energy consumption to a 90

 

Thanks for all your input.

 

Martin

[Jambo]

Our batteries are 6x Trojan T105s (3 series pairs in parallel) which give us 675Ah at 12V. The Combi delivers 2kW continuous.

 

We have a washing machine but don't use it because it sucks water too quickly and we'll be getting rid of it. Theoretically we could probably run it off our Combi as it just squeaks in below the continuous power limit and in summer we could probably run it purely on solar on a good, sunny day with the batteries charging in the afternoon. But when we did use it in the early days I only used the generator.

 

Washing temperature definitely has a big impact on energy demand in the wash cycle (the energy demand is mostly in the water heating, the spin cycle doesn't use much at all). And as far as I'm aware, the drying cycle of a washer/dryer uses much more energy (2 to 3 times as much maybe?) than the washing cycle. I wouldn't like to bet how long your batteries would last being put under that kind of load on a regular basis. If you really must have a washer/dryer it might be better for you to get the 3kW Honda and power it directly?

 

But your profile lists you as London based, we are too. We use laundrettes, service washes and from time to time https://www.laundrapp.com and it works fine without a washing machine. Also consider the water issue. You want enough water supply to last you two weeks and doing the laundry will make a substantial dent in that. Is your tank big enough? The water queues in London can be quite big!

Edited April 5, 2016 by Jambo

[WotEver]

I'd love to replace our 4x245W panels with 320W at some point which I believe would be fine because the controller simply maxes out at 80A and so it wouldn't make use of the last 25A or so available from the panels...

 

The controller couldn't care less about the extra power, it's the voltage that will kill a controller if it exceeds the controller's maximum. If the 320W panels result in a voltage on a bright cold day that's below the controller's maximum that would be fine.

 

Tony