DC solar cable length

[Wrath of Khan]

Just a quick question. Retard me didn't double check where the DC cables come out from the solar panels, I though they were at the "top" center of the panel. Alas, they're each side.

I'm running them into a micro-inverter so all the 4 panels cables must reach into the inverter.

Is it ok if I extend 1 cable on the panel say 1m, the other stays the same? So under a panel lets say the positive cable is 1.2m long and the negative cable is 2.2m long..

oh and one more thing, some of the cables on the back of the panel need to be extended by 50cm or 1m, am I allowed to cut the wire on the back of the panel and just splice a 4mm2 solar cable in there? Do I really need to go and buy more MC4 connectors and join all that to extend a wire 50cm to 1m max?

 

[TheChamp]

Joints are bad and you really need to avoid them if you can, its not that one cable is longer than the other by a meter, that is negligible, the problem is that a joint is a weak spot, it will no longer have the insulation and protection, it will get moisture over time and can affect the system.

Just get the MC4s and do it right.

 

[znh]

Is it ok if I extend 1 cable on the panel say 1m, the other stays the same? So under a panel lets say the positive cable is 1.2m long and the negative cable is 2.2m long..

Yes there is no issue with having different cable lenghts on PV. High voltage and low current means that voltage drop is not an issue. I would suggest you buy some MC4 connectors and make some extensions that plug into a panel lead and into your microinverter. If you cut the original MC4 off the panel you lose the warranty on the panel

 

[Geoff.D]

its not that one cable is longer than the other by a meter,

As with batteries, surely it is best practice to ensure the pos and neg wires are the same length?

 

[TheChamp]

As with batteries, surely it is best practice to ensure the pos and neg wires are the same length?

It is, but as long as the difference is kept to a minimum it won't have an impact. It is much more important in batteries, especially if you have a couple of them, because since you are charging them any difference will result in unbalanced batteries overcharging and undercharging.

It's slightly different with solar, it is supplying power, the panels are not identical anyway so the extra resistance will be just that, at a meter difference it won't even register on your multimeter. In a string of series panels it will be just the panel that's supplying 0.00... something volts less, which is a non issue, even in parallel it won't be enough to make any noticeable difference. Solar is also generally at high voltage so it will be less affected, unless you have smaller panels where every volt counts.

 

[Username:]

As with batteries, surely it is best practice to ensure the pos and neg wires are the same length?

Generally with home PV all the panels are connected in series strings.

In Series circuits the length of cables between connections does not have to be equal.

The thing I see a lot of DIY get wrong is to keep the Positive and negative wires close to each other.

Installed incorrectly you will have this nice big loop of your roof.

In making sure that I always have Positive and Negative running close to each other my negative wires is much longer than the positive wire

 

[Wrath of Khan]

ok cool thanks for the info, I will buy some 4mm solar cable and I found a pack of 10 pairs of MC4 connectors on TakeAlot, I will get knitting next week Now to try and lug all the panels onto the roof... this should be fun

 

[TheChamp]

ok cool thanks for the info, I will buy some 4mm solar cable and I found a pack of 10 pairs of MC4 connectors on TakeAlot, I will get knitting next week Now to try and lug all the panels onto the roof... this should be fun

How big?

 

[Wrath of Khan]

how big the panels? they are 385w JA Solar ones, 20kg each. 1.05m x 1.77m

 

[HowTo]

ok cool thanks for the info, I will buy some 4mm solar cable and I found a pack of 10 pairs of MC4 connectors on TakeAlot, I will get knitting next week Now to try and lug all the panels onto the roof... this should be fun

Use a Dektile. Much easier takes 16 cables. Tile roof get the Lead one.

 

[HowTo]

ok cool thanks for the info, I will buy some 4mm solar cable and I found a pack of 10 pairs of MC4 connectors on TakeAlot, I will get knitting next week Now to try and lug all the panels onto the roof... this should be fun

Use a descend crimper, no side cutter. In the long run you will have better connection.

I would like to solder those point for durability.

 

[Wrath of Khan]

Use a Dektile. Much easier takes 16 cables. Tile roof get the Lead one.

I've got a corrugated metal roof, with the micro-inverters I only have one AC cable running down from the roof into the house

 

[Wrath of Khan]

Use a descend crimper, no side cutter. In the long run you will have better connection.

I would like to solder those point for durability.

I can't believe how expensive a solar crimping tool is... I only have those normal crimpers and pliers look like they take forever solder would be way better

 

[Wrath of Khan]

Use a descend crimper, no side cutter. In the long run you will have better connection.

I would like to solder those point for durability.

what's a decent one that you've bought? The ones I see are like R1,000.... ughhh

 

[HowTo]

what's a decent one that you've bought? The ones I see are like R1,000.... ughhh

Have not bought one yet. Need to have one for maintenance.
Try this one

Solar Connector MC4 Crimping Tool

This is an industrial quality Multi-Contact crimping tool for solar MC4 connectors from 2.5mm - 6mm solar cable. The added lug locator for positioning the lugs makes the job a whole lot easier. The excellent handling, easy exchange of the crimping insert lugs. This Tool is an industrial...

www.inverter-warehouse.co.za

 

[Wrath of Khan]

Have not bought one yet. Need to have one for maintenance.
Try this one

Solar Connector MC4 Crimping Tool

This is an industrial quality Multi-Contact crimping tool for solar MC4 connectors from 2.5mm - 6mm solar cable. The added lug locator for positioning the lugs makes the job a whole lot easier. The excellent handling, easy exchange of the crimping insert lugs. This Tool is an industrial...

www.inverter-warehouse.co.za

Ratchet Crimping Plier 9" Insulated Terminals, TOTAL TOOLS

Crimping range: 0.5-6mm² For insulated terminals and butt connectors AWG: 20-10 Ratchet crimping plier length: 9” This ratchet crimping plier has a unique ABS handle design Pressure force can be adjusted, fit for various terminals This ratchet crimping plier is packed by blister card This...

www.altiven.co.za

what about that? Is it a ratchet crimper that is needed?

 

[TheChamp]

I can't believe how expensive a solar crimping tool is... I only have those normal crimpers and pliers look like they take forever solder would be way better

As longs as solder does not interfere with how the metal part sit inside the connector. I wouldn't bother about the proper crimping tool if you don't have one, just make use of what you have and do a proper job, there is no pressure on the connector so disconnection should not be an issue.

 

[HowTo]

I just bought one don't know if you will get it at that price again.

 

[Wrath of Khan]

JA Solar QC4.10 1000V Pre-Terminated cable 0.6m single

JA Solar QC4.10 1000V Pre-Terminated cable 0.6m single

www.geewiz.co.za

I'm trying to work out why this is so cheap? Is this a 60cm DC cable with MC4 connectors each side?

 

[TheChamp]

JA Solar QC4.10 1000V Pre-Terminated cable 0.6m single

JA Solar QC4.10 1000V Pre-Terminated cable 0.6m single

www.geewiz.co.za

I'm trying to work out why this is so cheap? Is this a 60cm DC cable with MC4 connectors each side?

Yes, similar to what you get on solar panels.