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Build a decent solar setup


robtheplod

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2 hours ago, robtheplod said:

I'm looking at wiring and thought as the panels have 4mm i probably need to go for 6mm for the main wiring along the roof. Not sure on the voltage drop as it will go a fair way along the boat - would i need to go larger?

I must admit that volt drop was one of the reasons I went for the 120v (170w) panels. 

The volt drop will be the same but the effect on the 'end voltage' will be significant on the lower voltage panels.

 

If I get 1 amp coming out of the panel I still get around 9-10amps going into the battery.

 

 

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5 hours ago, robtheplod said:

Excellent thanks so much for all the replies.

 

I'm looking at wiring and thought as the panels have 4mm i probably need to go for 6mm for the main wiring along the roof. Not sure on the voltage drop as it will go a fair way along the boat - would i need to go larger?

 

Also cant seem to find a solar 3 way cable junction box that will need to go under the first lot of panels. Would these be ok?

https://www.amazon.co.uk/gp/product/B01N30QTDA/ref=ox_sc_act_title_2?smid=A1IX7WRB7J03LQ&psc=1

 

thanks!!

 

Have a look at MC4 connectors Ebay Amazon etc

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On 19/06/2020 at 08:46, WotEver said:

 

If you're fitting 4 then I'd consider wiring them in two parallel series pairs.  If that sounds complicated, it's not :)  Basically, two panels in series, plus another pair in series, then parallel the two pairs. That way, if one panel is in shade you only lower half of the output instead of the whole thing, and the voltage is still high enough for the MPPT to achieve a decent output.  It's always worth arranging the wiring such that you can experiment in the future - do they work better all in series, all in parallel etc.

Wot Wotever says.^

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On 21/06/2020 at 09:37, Cas446 said:

Search for Magpads and Aluminium U channel on eBay.

 

 

Thanks for that, found the U channel - didn't know what it was called...

 

I saw those type of magnets then came across these so got a few to test:

https://e-magnetsuk.com/magnet_products/work_holding_magnets/pot_magnets/external_threaded_stud.aspx

E1007 - 16Kg pull force needed. I put these on the boat almost couldn't remove them again even though they are small!

Edited by robtheplod
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11 hours ago, Alan de Enfield said:

I must admit that volt drop was one of the reasons I went for the 120v (170w) panels. 

The volt drop will be the same but the effect on the 'end voltage' will be significant on the lower voltage panels.

No, the voltage drop will be significantly less because the current will be significantly less (I = W/E). But yes, whatever voltage drop there is will be a much smaller percentage of panel voltage. 

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45 minutes ago, robtheplod said:

just having a thought, I'd like to get the kit and test off the boat. I'm assuming the mppt controller must be connected to a battery to work?  Would a cheapy car battery be ok for testing purposes?

Yes it must, and it must be connected before you connect the panels to it.  Yes, an ordinary car battery will be fine.

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7 hours ago, WotEver said:

Yes it must, and it must be connected before you connect the panels to it.  Yes, an ordinary car battery will be fine.

thanks for this, much appreciated

 

I'm primarily using the Bimble Solar site for kit, and keen to source an isolator i can put in between panels and MPPT as i understand this is good practice?  I've come across this one which seems to be ok not sure on the ratings - any thoughts?

https://www.bimblesolar.com/extras/connectors/KG20B T106GB

 

Edited by robtheplod
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31 minutes ago, robtheplod said:

thanks for this, much appreciated

 

I'm primarily using the Bimble Solar site for kit, and keen to source an isolator i can put in between panels and MPPT as i understand this is good practice?  I've come across this one which seems to be ok not sure on the ratings - any thoughts?

https://www.bimblesolar.com/extras/connectors/KG20B T106GB

 

Having some means of disconnecting the controller certainly is good practice, but I also work on the principle that keeping it simple and reducing the number of 'joints' is also good practice.

If the controller is in an easily accessible place, screwdriver alongside, & you can just 'do as I do', loosen the screw 1/2 a turn and pull one wire out - takes a 'second'.

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43 minutes ago, robtheplod said:

thanks for this, much appreciated

 

I'm primarily using the Bimble Solar site for kit, and keen to source an isolator i can put in between panels and MPPT as i understand this is good practice?  I've come across this one which seems to be ok not sure on the ratings - any thoughts?

https://www.bimblesolar.com/extras/connectors/KG20B T106GB

 

I used dc rated mcbs , you could just disconnect the MC4 connector?

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32 minutes ago, peterboat said:

I used dc rated mcbs , you could just disconnect the MC4 connector?

thats sounds like a good idea re MCBS - i notice Bimble sell these in their kits but designed to go between battery and MPPT. Not too sure what size to go for but as its just acting as a switch a large 62a should do??!!

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18 minutes ago, robtheplod said:

thats sounds like a good idea re MCBS - i notice Bimble sell these in their kits but designed to go between battery and MPPT. Not too sure what size to go for but as its just acting as a switch a large 62a should do??!!

I got the MCBS as part of the bimble kit but after a discussion and advice on here I used 40 amp fuses at the battery and used the breakers between the panels and the controllers. makes it really easy to "switch off" the panels if you need to.

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1 hour ago, waterdog said:

I got the MCBS as part of the bimble kit but after a discussion and advice on here I used 40 amp fuses at the battery and used the breakers between the panels and the controllers. makes it really easy to "switch off" the panels if you need to.

You really should only have a fuse between controller and batteries, I have mentioned this to Bimble(and customers buying kits from Bimble)...but they keep recommending overcomplicating things.

 

Had a chap a couple of weeks ago, boat with a trad stern and engine underneath. He had installed a 60A breaker between his batteries and an Adverc charge controller(where his panels ran to). Bimble said good idea. Unfortunately, due to the location of the breaker...on his trips into the boat, he kept knocking the breaker off, thus allowing his 500W of panels at 24v  in series to destroy his controller when he flipped it back on several times. 

Bimble sent several replacement panels out, until finally replacing the controller.

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20 minutes ago, matty40s said:

You really should only have a fuse between controller and batteries, I have mentioned this to Bimble(and customers buying kits from Bimble)...but they keep recommending overcomplicating things.

 

Had a chap a couple of weeks ago, boat with a trad stern and engine underneath. He had installed a 60A breaker between his batteries and an Adverc charge controller(where his panels ran to). Bimble said good idea. Unfortunately, due to the location of the breaker...on his trips into the boat, he kept knocking the breaker off, thus allowing his 500W of panels at 24v  in series to destroy his controller when he flipped it back on several times. 

Bimble sent several replacement panels out, until finally replacing the controller.

Yes I have mcbs on panels and to batteries, both easy to use but can't get turned off by accident........yet

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Thanks for the replies. So with the intended MPPT being a 50amp one, the fuse/MCB should be lower so would 40amp suffice?

 

Is there a preferred way to have an inline fuse?  The Bimble kit uses 10mm cable here so something that can connect to this?

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35 minutes ago, robtheplod said:

Thanks for the replies. So with the intended MPPT being a 50amp one, the fuse/MCB should be lower so would 40amp suffice?

No, it should be higher. (Unless you want it to blow whenever the controller is putting a decent charge into the batteries) 


The fuse is to protect the cable, not the device, so assuming you’re using something chunky (like the 10mm2 you mentioned) then an 70A  Megafuse should survive. 
 

 

Edited by WotEver
Changed the fuse rating to one they actually supply!
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26 minutes ago, robtheplod said:

Thanks for the replies. So with the intended MPPT being a 50amp one, the fuse/MCB should be lower so would 40amp suffice?

 

Is there a preferred way to have an inline fuse?  The Bimble kit uses 10mm cable here so something that can connect to this?

 

Your fuse should be determined by the current carrying capacity of the cable - NOt the output of the MPPT.

If you have (say) 20 amp rated cable with a 40 amp fuse the result could be disasterous  in the event of a short.

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Having half read this and other threads on solar panels, it has dawned on me that there is a contratiction in requirements.
The BSS requires a battery isolation swicth which totally isolates the batteries. In its self this is a good thing, however there are known problems. If one just isolates the batteries and the engine is running, then the alternator blows up, it would also appear your solar controller also blows up for the same reason. Some battery isolating switches come with a extra pair of contacts which break before battery isolation, this is to turn the alternator off first, It would appear to be a good idea to have such a switch when you have solar panels too.
A switch like this will do the job. - https://www.autoelectricsupplies.co.uk/product/139/category/30

Edited by Ian Mac
forgot the link.
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On 22/06/2020 at 16:59, robtheplod said:

Thanks for that, found the U channel - didn't know what it was called...

 

I saw those type of magnets then came across these so got a few to test:

https://e-magnetsuk.com/magnet_products/work_holding_magnets/pot_magnets/external_threaded_stud.aspx

E1007 - 16Kg pull force needed. I put these on the boat almost couldn't remove them again even though they are small!

I used magnets for my first (small) solar installation. The disadvantage was that the roof paint under the magnets bubbled and needed re-doing

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1 hour ago, Ian Mac said:

Having half read this and other threads on solar panels, it has dawned on me that there is a contratiction in requirements.
The BSS requires a battery isolation swicth which totally isolates the batteries. In its self this is a good thing, however there are known problems. If one just isolates the batteries and the engine is running, then the alternator blows up, it would also appear your solar controller also blows up for the same reason. Some battery isolating switches come with a extra pair of contacts which break before battery isolation, this is to turn the alternator off first, It would appear to be a good idea to have such a switch when you have solar panels too.
A switch like this will do the job. - https://www.autoelectricsupplies.co.uk/product/139/category/30

 

Read the BSS carefully - the 'master switch' EXCLUDES things like battery chargers, bilge pumps and solar panels.

 

 

BSS Section 3.6.2

 

All d.c. electrical circuits
must pass through a battery
isolator, except those which
feed equipment requiring a
continuous supply which
must be protected by a
suitable fuse or circuitbreaker


Do all electrical circuits pass through a battery isolator, or are those requiring a continuous supply otherwise protected?
Identify any d.c. electrical circuits bypassing the battery isolator.
Check that any electrical circuits bypassing the battery isolator supply the
following equipment:
• automatic bilge pumps;
• security alarms (including marine radios);
• fire pumps;
• electronic navigation equipment with memories;
• any other equipment where the manufacturer’s instructions indicate or
specifically require direct connection to a battery, such as diesel‐fired
central heating boilers;
• battery charger outputs;
• inverters or combination inverter/chargers;
• solar panels and wind turbines.
Check electrical circuits supplying any equipment on the specified list, and
which bypass a battery isolator, for the presence of a fuse or circuit‐breaker,
where the circuit can be seen.

 

 

It is worth knowing these things so you can correct the examiner when he fails your boat !

Edited by Alan de Enfield
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3 minutes ago, Alan de Enfield said:

 

Read the BSS carefully - the 'master switch' EXCLUDES things like battery chargers, bilge pumps and solar panels.

That is interesting as our surveyor - god rest his sole, made us fit a total isolation switch, as well as a swich which turns of everything but those you mention, which we use when we leave the boat.

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1 minute ago, Ian Mac said:

That is interesting as our surveyor - god rest his sole, made us fit a total isolation switch, as well as a swich which turns of everything but those you mention, which we use when we leave the boat.

I have occasionally had the same 'sort' of surveyor, (one who makes up his own rules), which is why it is worth reading and memorising the important parts of the requirements.

It seems to be a waste of time making a formal complaint to the BSS so you need the knowledge to tackle the examiner whilst he is on site.

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Personally I prefer to have a master switch that is exactly what it says it is, ie one that TOTALLY isolates the battery. I then know that once I have turned that switch off, it is safe to do absolutely anything else including work on the battery cables. The one exception that I have had to make, is that my battery monitor connects directly (with a fuse) to the battery terminals. Anything else that needs to be isolated, such as the domestic supply, has it's own separate master switch.

 

I admit this gave me a dilemma regarding the solar connection. To address this, I attached a small MC4 removal tool to the master switch, in such a way that I cannot operate the switch without first carefully removing the tool (which could be done in a second in emergency). This reminds me that I must first either use the tool to disconnect the panels or else at least (usually easier) flip the switch that is in their cable.

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1 hour ago, Ian Mac said:

Having half read this and other threads on solar panels, it has dawned on me that there is a contratiction in requirements.
The BSS requires a battery isolation swicth which totally isolates the batteries. In its self this is a good thing, however there are known problems. If one just isolates the batteries and the engine is running, then the alternator blows up, it would also appear your solar controller also blows up for the same reason. Some battery isolating switches come with a extra pair of contacts which break before battery isolation, this is to turn the alternator off first, It would appear to be a good idea to have such a switch when you have solar panels too.
A switch like this will do the job. - https://www.autoelectricsupplies.co.uk/product/139/category/30

Solar and bilge pumps are allowed to connect to batteries according to my BSS guy

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