Solar Panels

[Adam1991]

Hi, could anyone help me confirms that these panels would work well with a 400ah 12volt battery bank? I’m almost certain they’re ideal but just thought to double check! 

https://clearcutconversions.co.uk/product/solar-panel-215w-12v-victron-energy-rigid-framed-mono-series-silver-black-new-product/

 

thanks! 
 

adam 

[robtheplod]

4 minutes ago, Adam Mc Gowan said:

Hi, could anyone help me confirms that these panels would work well with a 400ah 12volt battery bank? I’m almost certain they’re ideal but just thought to double check! 

https://clearcutconversions.co.uk/product/solar-panel-215w-12v-victron-energy-rigid-framed-mono-series-silver-black-new-product/

 

thanks! 
 

adam 

dont see why not... how many are you getting?

[IanD]

10 minutes ago, Adam Mc Gowan said:

Hi, could anyone help me confirms that these panels would work well with a 400ah 12volt battery bank? I’m almost certain they’re ideal but just thought to double check! 

https://clearcutconversions.co.uk/product/solar-panel-215w-12v-victron-energy-rigid-framed-mono-series-silver-black-new-product/

 

thanks! 
 

adam 

They'll work but they're very expensive -- have a look here for much cheaper alternatives (about half the price?) from a reputable supplier:

 

https://www.bimblesolar.com/panelcompare?sort=price_per_watt

[BEngo]

Which controller will you be using with the panels?

 

N

 

[blackrose]

I can't see the detailed specifications for those panels. What's the open circuit voltage (Voc)?

 

Also panels don't work on their own and how well they work very much depends on what controller you're intending connect them to.

[MrFish]

1 minute ago, IanD said:

They'll work but they're very expensive -- have a look here for much cheaper alternatives (about half the price?) from a reputable supplier:

 

https://www.bimblesolar.com/panelcompare?sort=price_per_watt

Totally agree. I am ordering the 295w perlight from them. Much better cost per watt and only slightly bigger dimensions.

[blackrose]

They are expensive. I bought a couple of 455w Canadian Solar panels from Bimble for £222 each including vat and delivery.

[GUMPY]

A lot of panels marketed as 12v panels have a VCC of 19-20volts which unless you have bright sunlight all the time or wire them in series do not give a big enough voltage differential between them and the batteries to get any meaningful charge from the MPPT controller into the batteries.

[blackrose]

1 hour ago, Adam Mc Gowan said:

I’m almost certain they’re ideal but just thought to double check! 

 

Good idea. I'm almost certain they're not ideal! 

[Adam1991]

Hi, thanks for your responses. We’ll be connecting up to a victron mppt 100 / 20 (or 50 can’t remember which at the moment) 

[pearley]

1 hour ago, blackrose said:

I can't see the detailed specifications for those panels. What's the open circuit voltage (Voc)?

 

Also panels don't work on their own and how well they work very much depends on what controller you're intending connect them to.

 

57 minutes ago, Loddon said:

A lot of panels marketed as 12v panels have a VCC of 19-20volts which unless you have bright sunlight all the time or wire them in series do not give a big enough voltage differential between them and the batteries to get any meaningful charge from the MPPT controller into the batteries.

VOC is 46 volts 

[Adam1991]

1 minute ago, pearley said:

 

VOC is 46 volts 

Hi Pearley, so x2 of these will work fine on a 12v narrowboat system? 

Also, is it safe to run 6mm sq cables from the mppt to the batteries? We currently have 6mm cables already installed and I’m aware they should be Atleast 16mm sq but will 6mm sq work ok for now? 

Edited May 10, 2023 by Adam Mc Gowan

[Jen-in-Wellies]

3 hours ago, Adam Mc Gowan said:

Also, is it safe to run 6mm sq cables from the mppt to the batteries? We currently have 6mm cables already installed and I’m aware they should be Atleast 16mm sq but will 6mm sq work ok for now? 

Depends how far the controller is from the batteries. The further they are, the more the undersized cables will drop the voltage. Voltage drop calculators are available on-line. You're going to have a fuse between the MPPT and the batteries too right?

[Adam1991]

1 minute ago, Jen-in-Wellies said:

Depends how far the controller is from the batteries. The further they are, the more the undersized cables will drop the voltage. Voltage drop calculators are available on-line. You're going to have a fuse between the MPPT and the batteries too right?

Hi Jen, it’s 3 metres from the battery box. Do you think they would cope with that distance? Yes we’ll definitely have a fuse between mppt and batteries. 
 

thanks 

[Jen-in-Wellies]

3 minutes ago, Adam Mc Gowan said:

Hi Jen, it’s 3 metres from the battery box. Do you think they would cope with that distance? Yes we’ll definitely have a fuse between mppt and batteries. 
 

thanks 

According to this calculator, it will drop 0.377V at 20A and 0.942V at 50A. Just about acceptable at 20A. More than I'd be happy with at 50A.

With 16mm^2 cable the voltage drops are 0.151 and 0.378V respectively.

 

[Adam1991]

That’s really helpful. The volt drops and cable size calculation have been a bit confusing for the solar setup so thanks for your advice. 

[Adam1991]

13 hours ago, Jen-in-Wellies said:

According to this calculator, it will drop 0.377V at 20A and 0.942V at 50A. Just about acceptable at 20A. More than I'd be happy with at 50A.

With 16mm^2 cable the voltage drops are 0.151 and 0.378V respectively.

 

Hi Jen, do you think this circuit breaker is good enough for that set up of 430w solar? 
 

or is a standard inline fuse also ok to use?  
 

(as in between the mppt and battery bank) 

Edited May 11, 2023 by Adam Mc Gowan

[Jen-in-Wellies]

3 minutes ago, Adam Mc Gowan said:

Hi Jen, do you think this circuit breaker is good enough for that set up of 430w solar? 
 

or is a standard inline fuse also ok to use? 

I've never used one of those, so can't say. My personal preference would be a suitably sized midi fuse and holder, which can take 16mm^2 cable, with the appropriate  crimp terminals,

Jen

I don't own any shares in 12Vplanet, nor am I on commission 😀. Just a convenient source of links to show what I'm talking about.

[Tony Brooks]

Assuming the solar will occasionally deliver it's rated output - a very doubtful assumption - 430W of solar equals about 33 amps at 13 volts, so on that front the circuit breaker you list will be OK. However, the fuse/circuit breaker is t protect the cable from the thousands of amps that might floe in the case of a short circuit, so you need to consider the maximum current capacity of the cable that you are using - 100 amps into a 6 sq mm CCSA cable with a 100 amp fuse could easily result in a fire.

 

The fuse/breaker between the MPPT and batteries needs to be mounted as close to the batteries as reasonably possible, but outside the battery case.

 

You should never have the panels connected to the MPPT without the batteries connected first, doing so is likely to set the MPPT to 24V. so you need a way of isolating the panels during maintenance.

 

[Puffling]

1 hour ago, Adam Mc Gowan said:

Hi Jen, do you think this circuit breaker is good enough for that set up of 430w solar? 
 

or is a standard inline fuse also ok to use?  
 

(as in between the mppt and battery bank) 

I bought exactly that breaker for my solar installation last year, then decided not to use it after a few people on here commented that it can develop a higher contact resistance over time. And believe me, with 20A flowing you want as little resistance in this side of the circuit as you can. It might work fine, but if it's dropping a volt or more at 20A (0.05 Ohms) you might find it getting dangerously hot with the dissipation.

 

If you don't go with @Jen-in-Wellies's simple fuse and holder recommendation, a quality DIN fuse or breaker and DIN rail enclosure will be sensible. Advantage of the DIN rail option is you can have your solar panel side breaker clipped on it and in the same box as well.

[PeterF]

There have been several people on this forum reporting problems with solar charging performance that has been tracked down to the poor performance of that type of breaker. The cylindrical type also have a bad reputation.

[David Mack]

If using a circuit breaker you need one rated for dc current. Many of those advertised are only rated for ac use, so check the specification!

I used a Tomzn branded circuit breaker, available from Bimble Solar or ebay.

[Quattrodave]

1 hour ago, David Mack said:

I used a Tomzn branded circuit breaker, available from Bimble Solar

 

I second the Tomzn breakers.  The breakers shown above are garbage and are more likely to cause problems...

[Adam1991]

Great advice folks, thanks! 

18 hours ago, David Mack said:

If using a circuit breaker you need one rated for dc current. Many of those advertised are only rated for ac use, so check the specification!

I used a Tomzn branded circuit breaker, available from Bimble Solar or ebay.

Hi David, would that breaker work on a system providing 430 watts total solar? 
 

also, should there be a circuit breaker on the mppt to panel side and then an inline fuse between mppt and batteries? 

[Tony Brooks]

58 minutes ago, Adam Mc Gowan said:

Great advice folks, thanks! 

Hi David, would that breaker work on a system providing 430 watts total solar? 
 

also, should there be a circuit breaker on the mppt to panel side and then an inline fuse between mppt and batteries? 

 

The circuit breaker should be rated in amps and I have already told you the THEORETICAL currant (Amps) the panels will produce, BUT you will never get that theoretical maximum in the UK, so the currant the breaker needs to handle will be less, probably far less. So look up the date for whatever you choose.

 

Whether you choose circuit breakers or fuses is up to you. As long as the panels to MPPT are adequate for the maximum currant the panels produce, you do not need a fuse/breaker between panel and MPPT. However, to make life easier for you some method of isolating the panels from the MPPT for the reason I explained before. That could be a removable fuse, circuit breaker, or switch.

 

You do need a fuse or circuit breaker between the batteries and MPPT (again, explained to you before). this needs to be as close to the batteries as reasonably possible, but not in any battery box or container.