Solar panels

 
 
 
 
 
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Solar panels

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Posted: 23.11.2021  ·  #1
Ok fitting a second panel new panel is 110 watt I think the old panel is 100 watt not sure as I can’t see the label do I wire them in series or parallel


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Solar panels

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Posted: 23.11.2021  ·  #2
Quote by hillton9

Ok fitting a second panel new panel is 110 watt I think the old panel is 100 watt not sure as I can’t see the label do I wire them in series or parallel


Before you go any further, make sure the output voltage is the same within 1. 25 volts.


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Re: Solar panels

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Posted: 24.11.2021  ·  #3
Robert...bit late as you obviously have the extra panel bought but you can pick up a 300watt panel nowadays for around 100 euro.... better option if you have the roof space.

It's always best to have matching panels but doesn't mean you can't add another as long as it's close in electrical values.....plenty of youtube videos on the subject. Also...hopefully some of our electrical wizards on the forum will chime in and give their thoughts...


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Re: Solar panels

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Posted: 24.11.2021  ·  #4
Have been looking at you tube but there matching 24 with 12 volt panels but not two 12 s ie 80 to 110 it’s says if they are very close ie 100 +110 that’s its ok to put them eather series or parallel but if it’s a 60 +110 it needs to be done in parallel because the smaller panel will bring down the output in the controller to the lower panel but if there matched within 10 watts it don’t mater which way there linked ,there has got to be someone out there can explain it better to me and the reason for doing it a certain way 🤪


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Re: Solar panels

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Posted: 24.11.2021  ·  #5
Few trains of thought on best ways Robert. Some people prefer one way over the other.
Wiring in Series has certain advantages, higher voltages with lower amps has less voltage loss and some controllers also prefer that input as less heat is generated.
There is also disadvantages of series configuration, one being is if one panel is shaded it can drastically decrease the input from all panels.
If it’s wired in Parallel then one shaded panel has no bearing on others and the input to the controller will not be affected. Matching the panels is important from the point of view of the smaller panel having a high voltage at the output side and the blocking diode on the smaller panel ability to handle that load…. with that in mind if the panels are within +/- 30w then it will OK. That is a much simplified explanation of it Robert, but the general gist is there.
I tend to wire panels in Series coupled to a good controller and the results work well. I also prefer the coupling joint to be soldered, heat shrunk and mounted well rather than using the ‘y’ joints supplied as I’ve seen those giving trouble with water ingress causing high resistance and severe loss or open circuits.


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Re: Solar panels

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Posted: 24.11.2021  ·  #6
The two most fundamental things to consider is what is the input maximum voltage of your controller and what gauge wire are your cables. Everything else is about efficiency but either of these could do damage.

If you wire in series, your input voltage to your controller will be ~36v, should be fine for most controllers but you need to check, in parallel it will be 18v.

If you wire in parallel, at maximum power you'll have approximately 12A (110+100)/18 passing through the cables to the controller and up to 15A (110+100)/14 passing through the cables from the controller to the battery. If you wire in series it would be 6A and 7.5A respectively.
Length of cable is important here too, if it's 5m of cable between the panel and the controller, you'd probably need a 4mm2 cable for 12A at 18V but if it's only 2m a 1.5mm2 cable would do. If it were a fresh install, I'd always recommend oversizing to futureproof, the cost differential between 10m of 6mm2 cable and 10m of 2mm2 cable is tiny with respect to the overall cost.

Once you're happy with the fundamentals, the next question is whether you have a PWM or MPPT controller, a PWM controller becomes increasingly inefficient as the input voltage increases relative to the output voltage, If it's PWM, you need parallel.

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Re: Solar panels

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Posted: 24.11.2021  ·  #7
I am thinking of adding a second panel to my van, but I have no way of telling the specs of the voltage on the panel, the only thing I know is its 140W. Is there any way of telling what its spec is without having to remove it and look. The panel is mounted roughly 5-10mm off the roof (factory fit)


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Re: Solar panels

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Posted: 24.11.2021  ·  #8
I added a 170W pannel to my bus recently and I had to wire in parralel as the max voltage my regulator would take is 30v plus the mismatched pannels. Really easy to do if you have the parralel connectors, start to finish was less than an hour including fixing to the roof.

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Re: Solar panels

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Posted: 24.11.2021  ·  #9
Quote by the fat controller

I am thinking of adding a second panel to my van, but I have no way of telling the specs of the voltage on the panel, the only thing I know is its 140W. Is there any way of telling what its spec is without having to remove it and look. The panel is mounted roughly 5-10mm off the roof (factory fit)


Is there anyway of getting a mirror under the panel and fining a label that looks something like this?

 


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Re: Solar panels

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Posted: 24.11.2021  ·  #10
Quote by the fat controller

I am thinking of adding a second panel to my van, but I have no way of telling the specs of the voltage on the panel, the only thing I know is its 140W. Is there any way of telling what its spec is without having to remove it and look. The panel is mounted roughly 5-10mm off the roof (factory fit)


You can test the voltage at the controller with a multimeter, most will be ~18v.


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Re: Solar panels

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Posted: 24.11.2021  ·  #11
Thanks for all the info think in series is the safe way to go here 👍


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Solar panels

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Posted: 24.11.2021  ·  #12
Quote by krissovo

I added a 170W pannel to my bus recently and I had to wire in parralel as the max voltage my regulator would take is 30v plus the mismatched pannels. Really easy to do if you have the parralel connectors, start to finish was less than an hour including fixing to the roof.

You could ask some of the mechanic's that service your van's, have they a camera probe, they could have a look under the panel at the spec, label.
I would hesitate to suggest you get onto the roof yourself, for obvious reasons.

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Re: Solar panels

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Posted: 24.11.2021  ·  #13
I had thougt about a mirror but its that close to the roof wouldn't be able to see it as well as that the I have to trace the cables back to the controller as its a sealed unit with the cables all going inside. I know it can accept input in the range of 9-32V unregulated.


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Re: Solar panels

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Posted: 24.11.2021  ·  #14
Quote by the fat controller

I had thougt about a mirror but its that close to the roof wouldn't be able to see it as well as that the I have to trace the cables back to the controller as its a sealed unit with the cables all going inside. I know it can accept input in the range of 9-32V unregulated.


Is there enough room to slide a phone stuck on a piece of card under it? Set it recording video and move it around under the panel, check the video when you take the phone back out.

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Re: Solar panels

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Posted: 24.11.2021  ·  #15
Aye that or set it to take a photo, on 10 seconds delay to allow you manoeuvre it into place


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Re: Solar panels

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Posted: 24.11.2021  ·  #16
There is room for a piece of card but def not a phone


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Solar panels

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Posted: 24.11.2021  ·  #17
Quote by the fat controller

There is room for a piece of card but def not a phone
as

Is it not on the build spec of the van, if it was factory fitted then they are the people to tell you what it is.


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Re: Solar panels

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Posted: 24.11.2021  ·  #18
That’s what I was thinking, need to brush up on my Spanish lol


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