Installing second folding panel into NDS SC 350M mppt

[ianto999]

Hello I have an 80w panel fixed on roof going into NDS controller.
I want to add an extra portable panel (for when van roof is in shade) so plan to buy a portable one.
The NDS has 2 solar inputs, so I can wire the new panel into this. This seems to have each input rather up to 180w. (OCV 29.5v)
My question isn’t answered in the brief manual and is:
‘If I connect another panel into second input, does the NDS assume this is separate, or does it appear linked to the existing 80w panel (either in series or parallel).’
I’m hoping it’s the former, so I can buy 160w panel and get full benefit of this, rather than being ‘tied’ to the 80w panel already there.

 

[ianto999]

Someone has done this, and I get the wiring part but not if in parallel etc.
The manual is also slightly unclear on using a panel bigger than 200w, I presume this part is meant to read that you connect to both 5 and 6, rather than just 5 alone?

 

[ianto999]

Reading another section of the manual says that they are ‘independent’ so it should be ok…

 

[Guigsy]

I wonder if it's just connecting the two sets of panels in parallel? It would mean you'd be losing a bit of efficiency if the panels aren't matched to produce similar voltage. If the inputs are truly independent, it would mean there's a pair of MPPT circuits in there.

 

[Jabstatt]

Just a quick aside….

Many windscreens on more recent vehicles incorporate a filter layer to reduce heat transmission. This is to increase aircon effectively.

It can be recognised by your photochromic glasses not working.

This also seriously reduces the effectiveness of solar panels.

Tony

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[ianto999]

I wonder if it's just connecting the two sets of panels in parallel? It would mean you'd be losing a bit of efficiency if the panels aren't matched to produce similar voltage. If the inputs are truly independent, it would mean there's a pair of MPPT circuits in there.

Thanks - it would seem hi-spec for a relatively basic unit to have 2 moots, when even victron units don’t do this. The circuit board etc is a mystery to my eyes! There is only 1 ‘coil’ which is what I presume changes voltage down to charging voltage, so I reckon only 1.

 

[Phill D]

I have the NDS mppt I have a 140w to 1 input and 120w into the second.
All works fine.
The only thing I notice is from the display screen when the controller decides if to harvest from 1 or both panels.
It will display the current from each panel separately.

 

[Guigsy]

I have the NDS mppt I have a 140w to 1 input and 120w into the second.
All works fine.
The only thing I notice is from the display screen when the controller decides if to harvest from 1 or both panels.
It will display the current from each panel separately.

Do they also display separate input voltages? If not, that would suggest only 1 MPPT circuit. Which is fine, provided the panels have similar voltage profiles.

 

[Phill D]

Do they also display separate input voltages? If not, that would suggest only 1 MPPT circuit. Which is fine, provided the panels have similar voltage profiles.

The voltage shown are only for cab and leisure battery status. Not panel voltage, which are 17.2v and 17.7v.
The panels are shown pictorially with an indication showing panels providing the charge I.e P1 or P1+ P2, but total current but how / if it is split between hab and cab.

Hope that makes sense

 

[ianto999]

Just a quick aside….

Many windscreens on more recent vehicles incorporate a filter layer to reduce heat transmission. This is to increase aircon effectively.

It can be recognised by your photochromic glasses not working.

This also seriously reduces the effectiveness of solar panels.

Tony

Been doing some more thinking (and asked chatgpt).
As the negative terminals are shared, this must make the panels act as in parallel. As the roof panel is only 80w, there is no point in me adding a bigger panel as a second (which helps save £ as well). Will start looking at the 100w fleabay panels, eco-worthy and dokio etc.
Looks as if I want a bigger portable, will need another MPPT attached to battery.

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[ianto999]

Thanks for all the help - thinking along with other people is great learning, and helps make better choices.