Jump to content

solar wiring - is this right?


waterdog

Featured Posts

Trying to get my head round the solar wiring for the boat, I've uploaded (I think) a diagram of how I think it goes, can someone advise if its right please. I'm not too sure about the breaker positions especially as I asked for isolation switches to go between the panels and controller but the info sheet on the supplier website (bimble) shows breakers between battery and inverter which I assume are already fitted to the existing inverter.

 

Hope I'm making sense here, please point me in the right direction, Thanks.

 

 

solar wiring.docx

Link to comment
Share on other sites

I would not have a 10 amp breaker that is easy to trip manually. I would probably use a fuse. If you isolate the batteries while the panels are connected your controller may set itself to 24 volts or be damaged in some way. 10 amp protection is only acceptable if the cables are rated at 10 amps or more.

 

Not everyone uses Microsoft  and your diagram does not render will in Libra Office but well enough for me to work out what you intend to do.

Edited by Tony Brooks
Link to comment
Share on other sites

5E89jSGEXOHTxd-kMRd5pZ9i4IAAiyBY7_wusVbGfXIOaciyXeyEWLlY-uHcI6DWZK6zdQ_xG-q1TMHCbhFHS99YB1fnc3qD2Oqie6NPkhzUlevNmqIo0Yfn5SK18YRkPGyQrA612TxV3rSoqMQBJcJrzAWbgEMWryLm7kzOt_bs9SQtM2XkZ4-28FDcV0ySZbPtheM0m63NbTVYigExfhXKlDEh3AAhDI6R_-kA4Ky9X_DD44mTh_GTADbqw9gm0FtOyDtk2SCg1qU5u-6Juvk9P81ds9-OW8_dDZ5XkS1zecXV8v8pFKBlzlWoB7wwiVRmzkI5kbwjfpSmIMhQwickE-hyUtmlQ0MfP7Gal93bV4PNWIraCZ55KVyO2OjyJ9fPy6YUq99j3JDbBQ2u3cXnrSROAgW1WOLFWbTfm4JWz_vm9BJaFkt_Ukp83hiyfZm2_QmfHVZxEf8ar16ttp_k1e9UWOuvvpRT9MveO1w5mQikFQmMNMhJtri6GJLnzJK3qqPbpQwZ8uO6kS9R3WoiV2FaDY8lYfD_U-awg-T5GGRWBRfnxeKJW5_SfNql5_7Z1ln30hxAP5ZkZXEbQYCm7m4Q-7VlFXup9sdDfDfB1AywOm7xiLR-YEnwQUvpIpeMGiDJ01Eoe2nYO7k0Xs8l=w165-h220-no

 

Hopefully this rough sketch is easier to see.

Tony / Alan, - Sorry, I'm probably not explaining it very well and while I'm quite happy connecting things together I'm certainly no electrical engineer.

 

The kit as supplied consists of , 2 x 305w panels, 1 x 40A mppt controller, 1 x 63A breaker & 1 x 10A breaker plus connectors / cable glands etc and a roll of 6mm cable. 

 

The breaker between the panels and controller is not so much for protection as I thought the controller deals with that automatically but more as a "isolator switch". I'm sure I've read on here somewhere that the ability to isolate the panels is a good idea ? I've probably misunderstood the use of a breaker for this.

 

Given the above kit what would you suggest is the best way to connect it all up ?

 

 

 

 

1 hour ago, reg said:

Diagram doesn't work locked my screen. Is it safe to download or dies it contain macros? 

Probably best to convert to an image and upload again

Sorry Reg, its just a word doc, no macros to my knowledge, I've posted a sketch above this post, hopefully you can see that ok.

Link to comment
Share on other sites

You need a decent isolator between the panels and the controller.  Not just because you should always connect the batteries to the controller before connecting the panels, but also so you can work on the downstream wiring without worrying about the sun coming out.

 

2 x 305W panels , so where on earth does a 10A breaker come into it?

Link to comment
Share on other sites

I don’t get what the 10A breaker is for. It’s too small for either side of the controller. You need a 30A breaker between the panels and the controller (you could use that 63A one if you wanted) and then you need a >40A fuse or breaker in the feed from the controller to the batteries, as close as possible to the batteries. 

Link to comment
Share on other sites

Is the cable 6mm OD of the insulation or 6 sq mm conductor cross sectional area? Is it twin cable in an outer insulator?  Is it maisn flex with much thicker outer insulation? I had mains flex supplied with my panel.

 

6mm insulation OD thin wall cable is rated at 70 amps while the same but "normal" cable will be a bit less. This takes no account for voltdrop that may require youto increase the conductor cross sectional area.

 

It seems a bit odd to me, supplying a 10 amp breaker when the system may produce so mush more - as Alan pointed out.

 

I still suggest that a breaker that can be easily tripped manually is not the bets item to use for protection between controller and batteries. Also as the 10 amp breaker is to protect the cables from excess battery current (not charging current) in the event of a short circuit that it needs to be close to the batteries but not in the battery box.

 

 

 

Link to comment
Share on other sites

13 hours ago, dor said:
9 hours ago, Mike the Boilerman said:

 

Maybe the cables supplied with the kit are only good for 10A.

 

 

You need a decent isolator between the panels and the controller.  Not just because you should always connect the batteries to the controller before connecting the panels, but also so you can work on the downstream wiring without worrying about the sun coming out.

 

2 x 305W panels , so where on earth does a 10A breaker come into it?

 

13 hours ago, WotEver said:

I don’t get what the 10A breaker is for. It’s too small for either side of the controller. You need a 30A breaker between the panels and the controller (you could use that 63A one if you wanted) and then you need a >40A fuse or breaker in the feed from the controller to the batteries, as close as possible to the batteries. 

Morning guys, Mike the cable is rated at 50A, It's the breakers that are really confusing me. The installation drawing shows a breaker between the controller and battery and also shows one in the cable to an inverter. Nothing between the panels and controller. The drawing doesn't show the rating of the breakers.

 

When I ordered the kit I asked for a switch to isolate the panels and they mentioned a 50amp one which ties in with the cable rating but I have a 63A and a 10A breaker.

Here is a link to the drawing,  https://www.bimblesolar.com/solardiagrams

I'm guessing that I don't need to worry about the inverter bit as the boat already has one ?

Link to comment
Share on other sites

12 minutes ago, Tony Brooks said:

Is the cable 6mm OD of the insulation or 6 sq mm conductor cross sectional area? Is it twin cable in an outer insulator?  Is it maisn flex with much thicker outer insulation? I had mains flex supplied with my panel.

 

6mm insulation OD thin wall cable is rated at 70 amps while the same but "normal" cable will be a bit less. This takes no account for voltdrop that may require youto increase the conductor cross sectional area.

 

It seems a bit odd to me, supplying a 10 amp breaker when the system may produce so mush more - as Alan pointed out.

 

I still suggest that a breaker that can be easily tripped manually is not the bets item to use for protection between controller and batteries. Also as the 10 amp breaker is to protect the cables from excess battery current (not charging current) in the event of a short circuit that it needs to be close to the batteries but not in the battery box.

 

 

 

Hi Tony, The cable is single core multistrand, conductor diameter is 3mm and 6mm diameter over the insulation. The cable is rated at 50A

Link to comment
Share on other sites

17 minutes ago, waterdog said:

Yes. Use one of these from the controller to the battery. Mount it as close to the battery as possible but outside the battery box. Use the 63A breaker between the panels and the controller. Sell the 10A breaker on eBay. 

  • Greenie 1
Link to comment
Share on other sites

If you wanted a breaker that would work in the panels to controller, use an ABB breaker they are rated at 70 volts DC and choose an ampage which will work, and bobs your uncle so they say. The problem is that a lot of MCBs arnt rated for DC so the contacts would burn out if opened or closed under load [I have used these MCBs and they work]

Link to comment
Share on other sites

56 minutes ago, waterdog said:

Hi Tony, The cable is single core multistrand, conductor diameter is 3mm and 6mm diameter over the insulation. The cable is rated at 50A

Well 50 amp cable has a conductor cross sectional area of 6 sq mm. Note that - area - not diameter. A conductor diameter of 3mm gives a cross sectional area of just over 7sq mm.  The reason I am making a fuss about this is that suppliers and boaters seem to insist on using the incorrect units when dealing with cables. It matters not a jot what the cable insulation OD is. The vital thing is the conductor's cross sectional area. Apart from the fact you can use the conductor OD to calculate its cross sectional are the conductor OD is of no help what so ever.  Different insulation materials and thickness’s allow manufacturers to claim different maximum currant capacity but that is the current it will carry before excess overheating. Luckily we should do voltdrop calculations to ensure we minimise voltdrop and this includes length of cable run. Usually the need to minimise voltdrop ensures we use cables well within their maximum current capacity. I don't know how your supplier knew what sized cable to supply unless you gave them the cable run lengths.

 

If

Link to comment
Share on other sites

1 hour ago, waterdog said:

 

Morning guys, Mike the cable is rated at 50A, It's the breakers that are really confusing me. The installation drawing shows a breaker between the controller and battery and also shows one in the cable to an inverter. Nothing between the panels and controller. The drawing doesn't show the rating of the breakers.

 

When I ordered the kit I asked for a switch to isolate the panels and they mentioned a 50amp one which ties in with the cable rating but I have a 63A and a 10A breaker.

Here is a link to the drawing,  https://www.bimblesolar.com/solardiagrams

I'm guessing that I don't need to worry about the inverter bit as the boat already has one ?

 

Electrically you do not need a breaker between panels and controller because the panels will happily dump their output into a short circuit without damage. The beaker is their for your convenience and safety. A flick of a switch rather than covering the panels and ensuring the wind does not uncover them while you are working on the system or changing batteries.

 

The diagram you have is a generic one that is used for one to a large number of panels of varying output so the maximum output and the cable sizes can not be known. That is left for you to work out but you have those answers now.

 

No idea where the inverter breaker comes into it for conventional boat wiring rather than domestic off grid use. If you have an inverter it should be wired separately to the solar so should already have its own fuse/breaker installed.

 

Your diagram, as far as I could see, worked. It was the cable size, breaker rating and position that needed sorting out.

 

  • Greenie 1
Link to comment
Share on other sites

7 minutes ago, Tony Brooks said:

It matters not a jot what the cable insulation OD is.

The cable insulation thickness determines the voltage rating of the cable - for typical flexible mains lead it is rated as 300/500v.

This is because the insulation on the individual cores is suitable for up to to 300v, so you can handle a single core out of the cable can safely be handled safely at up to 300v.

The added thickness of the sheath means that the cable can be safely handled and is insulated at up to 500v 

 

The insulation has a minimal effect on the current rating and is normally dependent upon the temperature rating and material type of the insulation.

 

As the current rating is linked to temperature it will also depend on the application - a single core 'in free air' will have a higher current rating than a 'bunch of wires in trunking' or, running behind panels' where they cannot easily 'dump' their heat into the air.

  • Greenie 1
Link to comment
Share on other sites

23 minutes ago, peterboat said:

If you wanted a breaker that would work in the panels to controller, use an ABB breaker they are rated at 70 volts DC and choose an ampage which will work, and bobs your uncle so they say. The problem is that a lot of MCBs arnt rated for DC so the contacts would burn out if opened or closed under load [I have used these MCBs and they work]

Thanks Peter, the breakers are marked as DC so it looks like I have the right ones.

Thanks for all your help guys, it's a lot clearer in my head now and it's making sense ?

 

I'm off to pick up a few bits from midland and will keep you updated.

Link to comment
Share on other sites

13 minutes ago, waterdog said:

Thanks Peter, the breakers are marked as DC so it looks like I have the right ones.

Thanks for all your help guys, it's a lot clearer in my head now and it's making sense ?

 

I'm off to pick up a few bits from midland and will keep you updated.

No pobs, I have 3680 watts of solar which comes in on three runs, so my wiring and MCBs is different to most peoples, the panels can be either for my electric drive system, domestic or used to heat water via the immersion heater. For this reason I have the correct rated MCBs in the panels to controller.  Enjoy your solar as it really will make a difference to your life

Link to comment
Share on other sites

29 minutes ago, Tony Brooks said:

The reason I am making a fuss about this is that suppliers and boaters seem to insist on using the incorrect units when dealing with cables.

 

It isn't clear to me where the OP bought his kit from, but my personal experience of Bimble is they are pretty cavalier with their product descriptions and don't really give a toss about inaccuracies after you've paid the money.

 

I'm wondering if they sent a 10A breaker for use in the panel supply cable anyway, thinking/hoping/not caring that it will probably be just about big enough, given the panels are to be wired in series. 

 

Link to comment
Share on other sites

24 minutes ago, Mike the Boilerman said:

I'm wondering if they sent a 10A breaker for use in the panel supply cable anyway, thinking/hoping/not caring that it will probably be just about big enough, given the panels are to be wired in series. 

I could just not fathom out how it will work (Post #4)

 

307 watt panels in series will still be outputting 20+ amps at 12v via the MPPT (could be even more we don't know what voltage the panels are rated at)

 

To then stick a 10 amp breaker in the line just means that whenever the Sun shines the breaker will trip.

 

You can see on my monitor that the output from the panels (going into the MPPT) is 103 volts at 0.8 amps.

The MPPT takes this and 'converts it' to 14.7 volts and multiplys the current by 8x giving 5.9 amps.

 

If the OPs panels are rated at a similar 100+ volts, their 20 amp output could easily be 'multiplied' to ???? at 13-14 volts.

05-06-16.jpg

Link to comment
Share on other sites

30 minutes ago, Mike the Boilerman said:

 

It isn't clear to me where the OP bought his kit from, but my personal experience of Bimble is they are pretty cavalier with their product descriptions and don't really give a toss about inaccuracies after you've paid the money.

 

I'm wondering if they sent a 10A breaker for use in the panel supply cable anyway, thinking/hoping/not caring that it will probably be just about big enough, given the panels are to be wired in series. 

 

Ditto Run by the Sun.  When I bought my first panel years ago they supplied ordinary domestic mains twin core flex to wire it up. When I complained that this did not comply colour wise with the NMEA codes of practice they seemed unable to understand the point.

Link to comment
Share on other sites

26 minutes ago, Alan de Enfield said:

307 watt panels in series will still be outputting 20+ amps at 12v

 

But it isn't 307W at 12V is it? Its 307W at 30V approx, typically. So that's 10A peak current, near as dammit. 

Link to comment
Share on other sites

38 minutes ago, Mike the Boilerman said:

 

But it isn't 307W at 12V is it? Its 307W at 30V approx, typically. So that's 10A peak current, near as dammit. 

Maybe I'm not on the right wavelength - but :

 

The 10a breaker was going after the MPPT

The MPPT will have taken the 10a @30 volts and 'converted' it to 20 amps at 12v.

 

The 10a breaker will be permanently 'overloaded'.

 

My 170w panel @100 volts = 1.5 amps before the MPPT

The MPPT takes the 1.5 amps and 'converts' it to 12 amps at 12 volts.

 

The cable between the MPPT and the batteries will be seeing 12 amps.

 

Have I got it wrong ?

Edited by Alan de Enfield
Link to comment
Share on other sites

6 minutes ago, Alan de Enfield said:

Have I got it wrong ?

 

Well one of us has! I took the breaker to be for isolating the panels from the MPPT. 

 

If it is, it's too small really, but in practice solar panels never deliver full rated output as perfect optimum conditions never occur, so the panel current will never *quite* reach 10A. 

 

 

 

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.