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hi guys,i hope everyone ok, i`ve just bought a new solar panel 200w, with a 30amp mppt controller,i do  have an existing  100w panel going to a separate controller my question is will i be ok to get rid of my existing controller and run both panels through the new mppt controller making things a bit simpler,thanks in advance

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3 minutes ago, dreadnought said:

hi guys,i hope everyone ok, i`ve just bought a new solar panel 200w, with a 30amp mppt controller,i do  have an existing  100w panel going to a separate controller my question is will i be ok to get rid of my existing controller and run both panels through the new mppt controller making things a bit simpler,thanks in advance

 

Is the 'old' panel the same voltage as the new panels ?

 

Different brands of panels can have very different VoC's.

 

Mine for example are 120v, the ones on a previous boat were 19v.

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15 minutes ago, dreadnought said:

i`m not entirely sure what you mean,i just thought they were 12v !!! 

Nope, they come in all sorts of voltage. The only thing one can say with confidence about yours is that they are > 12 V. The controller regulates the voltage to maximise the output from the panels under any conditions of illumination and to match the battery demand. It's basically a fancy invertor. Mixing panels of substantially different Voc may destroy one of both sets, and is unlikely to be better than one set alone.

Edited by Onewheeler
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31 minutes ago, dreadnought said:

i`m not entirely sure what you mean,i just thought they were 12v !!! 

 

 

No.

 

What is the VoC printed on each of your panels - you CANNOT mix up panels.

 

Take mine for example, on a bright summer day they are up to 120v output, this 120v (at say) 1 amp.

 

Look at the picture of my controler;

 

The bottom left shows the voltage / current coming out of the panel and the centre number shows that voltage / current going into the batteries.

 

You can see that there is 91.6 volts at 0.5 amps coming from the panel to the controller, the controller than takes this and makes it into a suitable voltage that the battery will accept ( 14.2 volts at 3.3 amps)

 

You do know that a 12v battery is not 12 volts and needs charging at up to 14.6 volts.

 

 

18-2-18.jpg.323276ab80e63d2c7bb4a852ad384f23.jpg

Edited by Alan de Enfield
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If you cannot get to the manufacturers data label on the back, count the number of cells on the panel. I suspect the 100W Panel will have 36 Cells and the Voc will be 18 volts the current max about 5.6 Amps The new 200 W panel could be 18 volt but is more likely to be a 72 cell with a Voc of 36 volts and a current of 5.6 Amps.  If the Amps are the same and your new MPPT controller has a maximum input voltage above the two Voc values (probably 18+36=54volt) then the panels could be put in series and just use the new controller. Wiring in series is not optimal for the partial shading you get on canals.  You can only wire them in parallel if the Voc values are the same or very near the same.

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7 minutes ago, dreadnought said:

thanks everyone for well explained answers,i think the best for me is to keep them separate,it just means i`ll have two controllers one per panel.

 

No, just look on the labels on the panels, if the VoC are close (say 19v and 21v) then it is far simpler to just use the one controller.

You need to minimise the number of connections on your batteries.

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On 28/01/2021 at 17:53, Alan de Enfield said:

 

No, just look on the labels on the panels, if the VoC are close (say 19v and 21v) then it is far simpler to just use the one controller.

You need to minimise the number of connections on your batteries.

many thanks,i`ll have a look at the existing one on the boat when i can get down after lockdown,cheers 

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On 28/01/2021 at 17:53, Alan de Enfield said:

 

No, just look on the labels on the panels, if the VoC are close (say 19v and 21v) then it is far simpler to just use the one controller.

You need to minimise the number of connections on your batteries.

i`ve just looked at my new panel and the spec is this,, nominal voltage 17.8,  voc 21.6v,  maximum power current 11.2amp,  short circuit current 21.1amp.

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1 minute ago, dreadnought said:

i`ve just looked at my new panel and the spec is this,, nominal voltage 17.8,  voc 21.6v,  maximum power current 11.2amp,  short circuit current 21.1amp.

 

If your boat panel is around the same voltage (say - 20/22Voc) than just connect up with one controller.

 

You really want to minimise the number of wires going to the battery terminals - the maximum allowed under the electrical specifications is 'four'.

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35 minutes ago, Alan de Enfield said:

 

If your boat panel is around the same voltage (say - 20/22Voc) than just connect up with one controller.

 

You really want to minimise the number of wires going to the battery terminals - the maximum allowed under the electrical specifications is 'four'.

Which specification are you referring to ?

 

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On 30/01/2021 at 15:20, Alan de Enfield said:

 

If your boat panel is around the same voltage (say - 20/22Voc) than just connect up with one controller.

 

You really want to minimise the number of wires going to the battery terminals - the maximum allowed under the electrical specifications is 'four'.

should i connect in series or parallel ?

should i connect them in series or parallel ? 

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10 minutes ago, dreadnought said:

should i connect in series or parallel ?

should i connect them in series or parallel ? 

 

Are you ever moored under the trees, or embankments ?

 

 

There are pros and cons, and its like cassette or pump-out toilets.

There are believers in one or the other.

 

 

 

 

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