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The Big Solar Install


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Ok, it’s not actually that big at 1.2kw but I thought I’d create a thread mostly for the benefit of myself so that I can document what I’m doing and therefore, not forget things n

I have limited knowledge of solar installs/12v systems from my campervan, the rest is entirely theoretical from reading/YouTube/12v boating Facebook group/this forum. 
 

The Plan

I’m reaching the end of my interior fit out and I need to get the boat ready for continuous cruising sharpish thanks to a very tight deadline for starting a new job. 

The entire electrical system in the engine bay needs an overhaul so not being one to do things by half, I plan on rewiring as I go along. 
 

The solar will be 1200w (3x400w panels) feeding whatever LA battery bank I currently have in there (lithium in the near future but not right now). 
 

Equipment 

400w solar panels (x3)

100/30 Victron MPPT controllers (x3) (Tick)

Victron Lynx Power in bus bar 

Solar isolators (x3)

Battery Isolator 

Shunt (?)

6mm solar cable MC4

Battery cable

Solar brackets 

Roof glands (x3)

Mega fuses

Crimps/ferrules/lugs/heat shrink/label/crimping tool 
 

Inverter/charger 

DC2DC charger (?)

Lithium Battery


The list likely isn’t finished so feel free to mention if I’ve forgotten anything. I’m going to start assessing the space to fit everything today, pictures incoming. 

Please jump in with any critique/knowledge/emotional support!!

Edited by ASupertramp
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10 minutes ago, robtheplod said:

Interesting... I'll be following this thread as solar is on my radar.....  what is your reasoning for using three separate controllers out of interest?

Primarily cost - 3 100/30 controllers cost less than 1 100amp controller (the Victron in particular). I've read that it also maximises efficiency and, should anything go wrong with one, I've still got solar from the other two. 

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4 minutes ago, ASupertramp said:

Primarily cost - 3 100/30 controllers cost less than 1 100amp controller (the Victron in particular). I've read that it also maximises efficiency and, should anything go wrong with one, I've still got solar from the other two. 

ok.. makes more cabling/switching needed though - have you got the room to mount them? :)

 

are you going to make three holes in your roof for the panels?  could you combine into one or use a mushroom. Generally best to keep holes to a minimum..?

also which panels do you have in mind, those nice black 400w ones on Bimble?

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2 minutes ago, robtheplod said:

ok.. makes more cabling/switching needed though - have you got the room to mount them? :)

 

are you going to make three holes in your roof for the panels?  could you combine into one or use a mushroom. Generally best to keep holes to a minimum..?

also which panels do you have in mind, those nice black 400w ones on Bimble?

 

This is the only downside but yes, three holes (one already present) or going via the mushroom nearest the engine room.

And those are the panels, hopefully get them on order today along with the rest of the equipment needed, that way I can start wiring all of the stuff inside, paint my boat roof and then fit the panels. 

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You state that you will be fitting solar isolators x 3, I assume you mean breakers between the solar panels and the MPPT controllers. Please be aware 

that some types of breaker/ fuse sold for solar are known to be poor such as the types shown, giving high resistance due to poor contacts. See a thread from last month which covered this very topic showing one with high resistance. https://www.canalworld.net/forums/index.php?/topic/115089-solar-controller-over-voltage-cutout-problem/#comment-2791824

 

I have a DC MCB (miniature circuit breaker) between my panels and MPPT, Bimble Solar sell these amongst other suppliers.

 

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3 minutes ago, PeterF said:

You state that you will be fitting solar isolators x 3, I assume you mean breakers between the solar panels and the MPPT controllers. Please be aware 

that some types of breaker/ fuse sold for solar are known to be poor such as the types shown, giving high resistance due to poor contacts. See a thread from last month which covered this very topic showing one with high resistance. https://www.canalworld.net/forums/index.php?/topic/115089-solar-controller-over-voltage-cutout-problem/#comment-2791824

 

I have a DC MCB (miniature circuit breaker) between my panels and MPPT, Bimble Solar sell these amongst other suppliers.

 

 

 

Thanks Peter! I noticed that thread the other day so by solar isolator I do mean breakers and plan on using the same as you, DC MCB between the panel and the MPPT, labelled to each panel. Does this seem right?

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4 minutes ago, ASupertramp said:

 

Thanks Peter! I noticed that thread the other day so by solar isolator I do mean breakers and plan on using the same as you, DC MCB between the panel and the MPPT, labelled to each panel. Does this seem right?

Yes, sounds right.

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40 minutes ago, ASupertramp said:

Primarily cost - 3 100/30 controllers cost less than 1 100amp controller (the Victron in particular). I've read that it also maximises efficiency and, should anything go wrong with one, I've still got solar from the other two. 

I doubt you'll need anything like 90amps though.  I have 525w and a 40a controller.  I now know that a 30a controller would have never been exceeded, and a 20a would be fine for 99.9% of the time.  Unless I've been misinformed, if I had a 20a controller, nothing bad would have happened if the solar energy exceeded 20a briefly, but the current into the batteries would top out at 20a.  In the real world, using a 20a controller would have made a negligable difference to my charging arrangements.  On that basis, in the real world, a 50a controller would be fine for you, as on the very rare occassion it was exceeded, you'll be fully charging your batteries that day anyway with more electricity going in that you can use.

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3 minutes ago, robtheplod said:

what sort of solar brackets will you use - flat or angled? - sorry forgot to say I'm really nosey!

 

Still deciding. It will definitely be something that I can angle but want to try and stay away from the triangle ones. 

 

3 minutes ago, doratheexplorer said:

I doubt you'll need anything like 90amps though.  I have 525w and a 40a controller.  I now know that a 30a controller would have never been exceeded, and a 20a would be fine for 99.9% of the time.  Unless I've been misinformed, if I had a 20a controller, nothing bad would have happened if the solar energy exceeded 20a briefly, but the current into the batteries would top out at 20a.  In the real world, using a 20a controller would have made a negligable difference to my charging arrangements.  On that basis, in the real world, a 50a controller would be fine for you, as on the very rare occassion it was exceeded, you'll be fully charging your batteries that day anyway with more electricity going in that you can use.

 

I was basing this on the Nominal PV power on the data sheet - the 100/50 goes up to 700w and I have 1200w?

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41 minutes ago, doratheexplorer said:

I doubt you'll need anything like 90amps though.  I have 525w and a 40a controller.  I now know that a 30a controller would have never been exceeded, and a 20a would be fine for 99.9% of the time.  Unless I've been misinformed, if I had a 20a controller, nothing bad would have happened if the solar energy exceeded 20a briefly, but the current into the batteries would top out at 20a.  In the real world, using a 20a controller would have made a negligable difference to my charging arrangements.  On that basis, in the real world, a 50a controller would be fine for you, as on the very rare occassion it was exceeded, you'll be fully charging your batteries that day anyway with more electricity going in that you can use.

 

Beware, as far as I know the above only applies to MPPT controllers. They are probably the vast majority now at the better quality end of the market, but at the Ebay type bargain end some claiming to be MPPT have been shown to be PWM controllers. Over input current may well destroy a PWM controller but within sensible limits the above is true of MPPT. 

 

Over voltage will damage either, but as the OP seems to be wiring the panels in parallel this is not an issue. Series connection to a single MPPT controller seems to have some benefit at low sun angles and strength in that it may charge sooner in the day than a parallel connected setup. However, then there would be shading considerations.

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4 minutes ago, David Mack said:

OP is proposing 3 panels and 3 controllers so no interconnected panels, series or parallel (other than at the 12V end).

 

I know, but I don't think he has taken on board the fact that MPPT controllers can run happily with an excess current input but limit the output current. I am also not sure if he has grasped that solar is unlikely to produce much more than 50% of the rated output in the UK, especially if mounted horizontally. There is also the claimed advantages of series connection into a single controller.

 

My main aim was to caution that Dora's post was potentially misleading.

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4 minutes ago, David Mack said:

Agreed. I think Dora's single 50A controller might be a bit tight, but a single 60A or 70A controller should be fine. And only one hole through the roof, and one set of battery wiring.

I can see no reason to complicate the installation by having 3 of everything. How about a spare breaker and a spare MPPT controller in the cupboard just in case? A panel total failure is highly unlikely.

The more you put in the more there is to go wrong.

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I can’t quote particularly well via the phone so just trying to summarise the advice given above. The suggestion being I can use a smaller regulator than a total of 90a for 1200w, in this case why are there mppt calculators and what about the information in the data sheet?

 

Ignoring for the moment the issue of having 3 mppt controllers and just assume I buy a 100a unit, why would I spec this at 60/70a?

Edited by ASupertramp
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1 hour ago, Tony Brooks said:

 

Beware, as far as I know the above only applies to MPPT controllers. They are probably the vast majority now at the better quality end of the market, but at the Ebay type bargain end some claiming to be MPPT have been shown to be PWM controllers. Over input current may well destroy a PWM controller but within sensible limits the above is true of MPPT. 

 

Over voltage will damage either, but as the OP seems to be wiring the panels in parallel this is not an issue. Series connection to a single MPPT controller seems to have some benefit at low sun angles and strength in that it may charge sooner in the day than a parallel connected setup. However, then there would be shading considerations.

Fair points.  I suspect the OP is using MPPT controllers. 

 

I look at it like this:

 

500w of solar might provide all your power needs for about 6 months.  This is true whether you have a 20a or a 40a controller.

 

If you're going to put in 1000w of solar, it's not because you need loads more power in June, it's because you're looking to extend the season, to maybe 8 months.  You're best bet for doing that is to install as many panels as you can afford.  If you save a bit of money on the MPPT controller, you can afford more panels.  Simple!

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43 minutes ago, ASupertramp said:

I can’t quote particularly well via the phone so just trying to summarise the advice given above. The suggestion being I can use a smaller regulator than a total of 90a for 1200w, in this case why are there mppt calculators and what about the information in the data sheet?

 

Ignoring for the moment the issue of having 3 mppt controllers and just assume I buy a 100a unit, why would I spec this at 60/70a?

 

 

Because you are trying to match the output of a solar panel at midday over the equator.

 

We are at around 53 degrees of latitide, we get much less 'power' from the Sun and probably, realistically, only achieve 50% of the theoretical panel output, in the Winter it will probably be as low as 2%-3% (maybe 10% on a really sunny cold day) of the theoretical output.

This is why, if you want to extend your solar collecting 'season' you have loads of panels- not for Summer where your batteries will be charged by 10:00am and the rest of the day's potential charging goes to waste (unless you use it to heat the water).

 

 

Edited by Alan de Enfield
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2 hours ago, ASupertramp said:

Still deciding. It will definitely be something that I can angle but want to try and stay away from the triangle ones. 

If panels are flat you only lose 10% compared to having them angled at 30deg.

The bonus being you get sun from any direction not just the one that the panel is pointing in.

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2 hours ago, ASupertramp said:

 

Still deciding. It will definitely be something that I can angle but want to try and stay away from the triangle ones. 

 

 

I was basing this on the Nominal PV power on the data sheet - the 100/50 goes up to 700w and I have 1200w?

What that data sheet is saying is that 700w of panels have no theoretical chance of producing more than 50a of current.  But in the real world, in the UK, you'll never get near that.  The Victron data sheet for the 250/85 shows a maximum of 1200w which is what you're having.  I'm saying that your 1200w of panels will very very rarely produce more than 50a in the uk and on the very very rare occassions that they do, you won't care that you could have squeezed a bit more battery changing out of them if you had a bigger controller, because you're batteries will be full to bursting anyway. 

 

If you buy the 60a controller, you'd save some money and could use that to get more or bigger panels, which would give you a longer season going further into the winter.  Or spend it on beer/chocolate etc.

48 minutes ago, ASupertramp said:

I can’t quote particularly well via the phone so just trying to summarise the advice given above. The suggestion being I can use a smaller regulator than a total of 90a for 1200w, in this case why are there mppt calculators and what about the information in the data sheet?

 

Ignoring for the moment the issue of having 3 mppt controllers and just assume I buy a 100a unit, why would I spec this at 60/70a?

Because sometime people living on the equator buy MPPT controllers.

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2 minutes ago, Alan de Enfield said:

We are at arund 53 degrees of latitide, we get much less 'power' from the Sun and probably realistically only achieve 50% of the theoretical panel output,

I regularly see 3.8kw coming from my 4.3kw array and occasionally 4.3kw Today even on a cloudy day it has been above 3kw for much of the day  but then I am at 51deg  😉

 

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16 minutes ago, doratheexplorer said:

Fair points.  I suspect the OP is using MPPT controllers. 

 

 

He is, but if you read his frits post he had looked at other threads, so one could expect others to do the same, hence the warning. Basically I agree with what you say as long as t is MPPT controler(s).

 

I still think that he needs to think about series connection, but it s up to him and his decision.

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59 minutes ago, ASupertramp said:

in this case why are there mppt calculators and what about the information in the data sheet?

 

And in addition to Dora's point it helps them sell punter more expensive equipment.

1 minute ago, ASupertramp said:

Ok so, if a 60a controller will suffice, can I simply use one of my 30a controllers (that I already have) wired into two panels (800) and the other taking a feed from the other panel? 
 

 

 

Yes, but have you looked into series panel  connection? Not only starting to charge sooner but thinner cabling required so may be cheaper cables.

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