RE-try. I need to reduce voltage from solar panels to mppt controller

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cygnusv

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I'm changing an old PWM controller to a new Victron 75/15 MPPT. My problem is that in full sun I'm reading 84 volts from the PV array, too much for the Victron. I'm certain that I've read somewhere that I can re-arrange the wiring on my 4 solar panels so that I have 2 pairs wired in parallel then connected to each other in series. This should result in about 42 volt output with increased amperage. Problem is getting my head around the wiring and the various connectors I would need to buy to complete the job. Any advice would be very much appreciated.

Apologies for the post with no/missing content. I was on my phone and it was throwing a wobbly. Thanks again
 
The four panels are all identical and wired in series. I want to split them into 2 pairs with each pair wired in parallel. I then want to connect the 2 pairs together in series. As I'm measuring an input voltage of 80+ volts I don't want to damage the Victron which is made to accept 75 volts max. As the panels are relatively small at 40 watts I don't want to spend the extra money on a bigger Victron unit
 
I also have four panels with two pairs of panels in series and then the pairs connected in parallel. This requires 2 two-into-one MC4 conectors, one of each polarity.

If you decide to go for two pairs in parallel with the pairs then connected in series, you will need 4 two-into-one connectors, with two of each polarity,.

Richard
 
RichardS said:
I also have four panels with two pairs of panels in series and then the pairs connected in parallel. This requires 2 two-into-one MC4 conectors, one of each polarity.

If you decide to go for two pairs in parallel with the pairs then connected in series, you will need 4 two-into-one connectors, with two of each polarity,.

Richard
Click to expand...

Forgive my Doh! Simpson's moment. I'm failing to visualise the connections. The idea of panels in series connected in parallel looks far more efficient than my original thoughts. Is there a diagram or sketch though? I'm struggling with the idea of only 2 x3 way connectors to do the dirty deed. Once I can actually see it, the old grey matter will wake up. At least, I hope it will. Thanks so far, Stu
 
I also use two-into-one Y branch MC4 connectors in case I want to switch setup on my panels.

The Y branch connectors you need will have:
2 female sockets and one male end
2 male sockets and one female end

I can do a diagram when I get to a PC as that's much easier to understand.

Just think about 2 panels at a time initially and wiring is simple because you start with one Y branch and everything is gendered and only fits one way. The Y branches do the parallel connection bit and that means you only need to worry about the series bit (not difficult).

1) Take one Y branch connector with 2 female sockets and one male end.
2) Plug Panel 1 +ve cable into the one of the 2 female sockets on the Y branch
3) Plug Panel 1 -ve to the +ve on Panel 2
4) Plug Panel 2 -ve to a second Y branch connector (but this one has 2 male parts and a single female connector)

You have now daisy chained 2 panels (i.e In series) to a pair of Y branch connectors.

Repeat the steps 1-4 using the free connections left on the Y branches and you now have 2 pairs of serially connected panels linked in parallel.

All you need to do now is connect the Y-branches to your original connections going to your MPPT regulator.

Pictures and a diagram would be really simple to understand but I don't have time just now to find a laptop and draw something, sorry.
 
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Why in series on a boat as shade one and they all suffer. At least in parlallel only the shaded panel suffers but does not bring down the others .
 
Rappey said:
Why in series on a boat as shade one and they all suffer. At least in parlallel only the shaded panel suffers but does not bring down the others .
Click to expand...
The OP is only using 40w panels. He hasnt said where he mounting them but not too hard to keep small panels in the sun. I use a single 100/30 Victron Smart Solar For four 180w panels, wired in series pairs then parallel. Works very well and we have minimal shading issues. Series panels need smaller wire cross-section compared to paralleling the same two panels
 
I found this diagram and hope it helps explain my text description.

SolarPar_Series.jpg
 
Rappey said:
Why in series on a boat as shade one and they all suffer. At least in parlallel only the shaded panel suffers but does not bring down the others .
Click to expand...
Is there such a thing as an MPPT controller which takes the wires in from each panel individually and then makes the best fist it can of whichever are shaded / working well ?

Boo2
 
Rappey said:
Why in series on a boat as shade one and they all suffer. At least in parlallel only the shaded panel suffers but does not bring down the others .
Click to expand...
With bypass diodes fitted either on the panel or separately then the shaded panel simply gets treated as if it’s just a slightly lossy wire.

And of course the higher the voltage the lower the amps and therefore the lower the loss of power in connecting wires.
 
Posters seem to assume that the panels have MC 4 cconnectors which I think are universal for domestic PV systems where the total voltage goes up around 380volts. Hence MC4 needed for voltage protection especially out in the elements. However OP has 40w panels presumably 20v max each and just ordinary wire or solder connections. OP needs to wire 2 panels in paralllel and wire them in series with the other 2 panels in parallel as per mistroma's diagram . He can use splice connectors or chocolate block connectors or just solder wires together. Of course he may have MC4 connectors in which case yes buy the paralleling connectors or just curt the MC 4 off and join wires together. ol'will
 
William_H said:
Posters seem to assume that the panels have MC 4 cconnectors which I think are universal for domestic PV systems where the total voltage goes up around 380volts. Hence MC4 needed for voltage protection especially out in the elements. However OP has 40w panels presumably 20v max each and just ordinary wire or solder connections. OP needs to wire 2 panels in paralllel and wire them in series with the other 2 panels in parallel as per mistroma's diagram . He can use splice connectors or chocolate block connectors or just solder wires together. Of course he may have MC4 connectors in which case yes buy the paralleling connectors or just curt the MC 4 off and join wires together. ol'will
Click to expand...

All the panels I've bought in the UK from 20W upwards have had MC4 connectors but, as you say, the principles are the same either way. :)

Richard
 
Boo2 said:
Is there such a thing as an MPPT controller which takes the wires in from each panel individually and then makes the best fist it can of whichever are shaded / working well ?

Boo2
Click to expand...
There are such things as panels with MPPT on a cell by cell basis.
 
lw395 said:
There are such things as panels with MPPT on a cell by cell basis.
Click to expand...
Sorry, missed this. So the panels / cells themselves have MPPT controllers built in ? What are they known as in the market, may I ask ?

Boo2
 
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