Need to Reduce solar voltage!!

[Hedges]

Lol Did you even read the post? I already disconnected 1 panel of each array. Total of 4 panels running now in safe zone. Trying to find a solution to lower voltage down 5-10 volts for previous setup.

Open junction box and move PV wire connection over one diode-bypassed section. That is, leave off 1/3 of the cells in one panel.

But consider 2s3p, with multiple orientations. That may fit within specs and physics, if not code, and make use of all cells.

 

[Jet]

Is that before or after you derate the wire? Anyway, it's not particularly unsafe and with that long of run wire is expensive. That's why you're getting the voltage dropped though. 10 AWG is your standard size/smallest typically used on houses solar wire. 535 watt panels are some big panels.

 

[740GLE]

Open junction box and move PV wire connection over one diode-bypassed section. That is, leave off 1/3 of the cells in one panel.

But consider 2s3p, with multiple orientations. That may fit within specs and physics, if not code, and make use of all cells.

He has two arrays currently 3s and 3s, each with a 10awg decently long “home run” to within 6 feet of the SCC, not sure if he can rig up one array to hold 4
panels.

 

[vashkoproimage]

That was an earlier post. I was replying to the last post.

But you said that it wasn't going to be enough production.

You will be much better off spending money on the right equipment. Rather than a bandaid, for the current mistake.

So does it make sense to buy a 20kw solar inverter for my future setup and use it for these 6 panels? That’s how much panels I have when house is built. Why run a new 20kw inverter when all I need 6 panels while building house. Does not make sense until larger setup is needed. This is just a temporary setup and will be torn down once new one is up. My current 6kw works just fine for what I’m using it. All I’m trying to do it connect as much as can for temporary setup. If I have extra equipment laying around why not just use what I have if temporary? Make sense to you?

 

[vashkoproimage]

He has two arrays currently 3s and 3s, each with a 10awg decently long “home run” to within 6 feet of the SCC, not sure if he can rig up one array to hold 4
panels.

 

[vashkoproimage]

And those wye connectors are near the SCC right?

Yes. 6 feet from controller.

 

[timselectric]

So does it make sense to buy a 20kw solar inverter for my future setup and use it for these 6 panels? That’s how much panels I have when house is built. Why run a new 20kw inverter when all I need 6 panels while building house. Does not make sense until larger setup is needed. This is just a temporary setup and will be torn down once new one is up. My current 6kw works just fine for what I’m using it. All I’m trying to do it connect as much as can for temporary setup. If I have extra equipment laying around why not just use what I have if temporary? Make sense to you?

If you just need a temporary solution.
Then hedges gave it to you.

Open junction box and move PV wire connection over one diode-bypassed section. That is, leave off 1/3 of the cells in one panel.

Do this to one panel in each 3s2p string.

 

[vashkoproimage]

Open junction box and move PV wire connection over one diode-bypassed section. That is, leave off 1/3 of the cells in one panel.

But consider 2s3p, with multiple orientations. That may fit within specs and physics, if not code, and make use of all cells.

Leaving 1/3 cell might actually work.? never took off the junction box and messed with it. Any tips on this?

 

[Hedges]

You can use it until it dies.
Our recommendation is to ensure voltage, even in cold, does not exceed SCC or inverter spec.

Leaving 1/3 cell might actually work.? never took off the junction box and messed with it. Any tips on this?

Designs vary. Some have 3 small boxes. Others one with a screwed on lid, others glued.

Disconnect from other panels in the string before messing with it! (shut off to stop current before disconnecting.)
If you can get in there, either move the PV wire or just short out any one bypass diode.

 

[pollenface]

I’m not running the entire system on only (1) set of 10 gauge wire bro. I’m running 2 sets of wires (3 panels) 160ft and second set of wire 100ft distance. And that’s total lengths including positive and negative runs. More than sufficient for 2s3p.

I can’t do 3s2p. The distance is too far and the voltage will be too low for my 10 gauge wire. I need the voltage to be on the higher side to keep amps down to get away from running long distance. That’s why I went with 2s3p. If I was to running 3s2p then I will have to run 8-6 gauge wire to be under the 3 percent voltage drop.

So are you doing 2s3p now? Problem solved?

 

[vashkoproimage]

You can use it until it dies.
Our recommendation is to ensure voltage, even in cold, does not exceed SCC or inverter spec.



Designs vary. Some have 3 small boxes. Others one with a screwed on lid, others glued.

Disconnect from other panels in the string before messing with it! (shut off to stop current before disconnecting.)
If you can get in there, either move the PV wire or just short out any one bypass diode.

 

[chrisski]

I’m not sure a DC to DC converter would work.

The only thing you can do is 2s2p with the current panels. Everything else is bigger wire, other SCCs, other panels.

Aside from DC to DC converters being inefficient and having heat losses, I’d want to see a 300 watt installation that has used one day after day, month after month, year after year. Actually I’d like to see several installations before I put one on my house.

I’d only do

 

[timselectric]

Probably short the diode in the center box.

 

[zanydroid]

I’m not sure a DC to DC converter would work.

The only thing you can do is 2s2p with the current panels. Everything else is bigger wire, other SCCs, other panels.

Aside from DC to DC converters being inefficient and having heat losses, I’d want to see a 300 watt installation that has used one day after day, month after month, year after year. Actually I’d like to see several installations before I put one on my house.

I’d only do

There’s at least one forum member using a reprogrammed SolarEdge as a DC DC converter.

There are millions of those installed in the US. Maybe not reprogrammed for hacking around voltage limits though.

 

[vashkoproimage]

Probably short the diode in the center box.

Thanks. I will try and open one up tomorrow. What do you mean by short out? Disconnect?

 

[Hedges]

Disconnect would be open circuit.

Short means solder a wire jumpered over the diode.

 

[timselectric]

Thanks. I will try and open one up tomorrow. What do you mean by short out? Disconnect?

Install a jumper from one side to the other.

 

[vashkoproimage]

Thanks guys. I will check it out tomorrow If I have any questions I will upload a picture. ?

 

[vashkoproimage]

Install a jumper from one side to the other.

Will shorting the diode make the battery’s drain when there’s no sun on panels? Or will the controller block that from happening?

 

[Hedges]

No such effect. It will be as though the bypassed PV cells aren't there.
Those PV cells will just put out Isc through the shorting wire.

 

[Ampster]

I will have to run 8-6 gauge wire to be under the 3 percent voltage drop.

How much drop have you calculated and is it below the starting voltage of your controller? If not, why does it matter?

 

[vashkoproimage]

No such effect. It will be as though the bypassed PV cells aren't there.
Those PV cells will just put out Isc through the shorting wire.

Thanks Hedges. I will take a few pictures tomorrow just to clarify before doing this. I love learning new things Happy thanksgiving.

 

[Hedges]

??

 

[SamDeleted]

#10 was also the wrong choice if starting with the cell size with 13A I_mpp and a non-trivial probability of going to parallel strings.

10awg , that's 5.25mm² , it's not particularly thin...

We normally use either 4mm² or 6mm² for solar


So surely OPs awg10 should be able to handle the current? Maybe it's a particular long cable run? not sure if OP said

 

[SamDeleted]

Lol Did you even read the post? I already disconnected 1 panel of each array. Total of 4 panels running now in safe zone. Trying to find a solution to lower voltage down 5-10 volts for previous setup.

Vash , from the beginning this has been a confusing thread, (I think for everyone?)


That's no small part down to your posts at the start being a bit unclear.. Now Tim's a big lad & can stick up for himself, I am sure...

But it is not his fault if he missed something you didn't state clearly in the first place!?