Heat sink question

[xhdskip]

Thank you upnorthandpersonal, I was just trying to get help with a pic, but Thank you again.
Now to answer some of the questions and comments. Let me scroll back up and take them in order
since my last post, I will answer to the best of my ability, but I'll admit, I'm not very knowledgeable.

 

[xhdskip]

How big are the arrays you use blocking diodes on?

Also, when operational, have you measured heat loss?

Curious f you think it’s worth it.

Will did a video and found a couple wats loss on each diode. Makes sense a larger array would make more loss requiring heat sink.

Blocking diodes are generally considered not worth it on this forum. I don’t have them on my three arrays I built, and the two sets of 4s3p arrays an my roof the contractors installed don’t have them.

Edit: with the way these are wired I understand your concern about shorting to the aluminum.

Edit: also looks odd the way the circuit breakers are ganged together. In addition to them being ganged at all, appears ganged with two open and two shut.

I've got 1 solar panel. When I first started this project I had 10 that put out 100W each.
But, the exwife got them and my first two inverters, etc in the divorce.

no, haven't checked heat loss, don't know how truthfully.

definitely worth it, it will or at least should stop my back feeding problem.
They were only $11. bucks each, so if they don't work, as long as I don't burn up another inverter
it's a small price to pay to protect this $4,000 inverter.

yeah I couldn't see how they would not at bare minimum energize the aluminum,
and was afraid they'd short out and cost me some big bucks.

that is a correct assumption on the breakers, when 1 set is open, the other is closed.

 

[xhdskip]

Can someone explain what problem these diodes are trying to solve?

I have a back feeding problem, so I figured with the breakers and the Blocking diodes, that should solve it.

 

[xhdskip]

They can only solve the problem of current flowing in the direction you don't want ... So being a solar forum, I'm guessing to allow a battery to charge when there is sun and not discharge through solar panels when the sun goes in.

But who knows? As there are 4 of them, maybe he's building a massive rectifier for his 2000W HiFi system's power supply? ?

That is exactly why I bought them, to keep the current from going in the direction I don't want it to.
Being a solar forum, yes, true enough, BUT not real worried about the sun at this point, I've only got 1 small solar panel.
20,000 watts, not 2,000.

 

[xhdskip]

Notice the big cable connector on the right side bridging the diode terminal and the case.? If it's for a wind pm turbine your in trouble.

in what way? What did I do wrong? PLEASE explain, and Thank you.

 

[xhdskip]

Most stud packed rectifiers have the case as cathode of diode. You will need thermal conducting insulator bushings for common heating sink mounting,

You will have 0.8-1.1 volt drop across regular silicon diode depending on current level so can get a lot of heating to dissipate for high currents.

At high current, hot-carrier Shockley diodes are not much better for voltage drop since they have a greater series resistance than regular silicon diodes that adds voltage drop to their lower conduction voltage point. Their use is usually when high frequency fast switching recovery time needed.

I don't know what a stud packed rectifier is.,
Could you please explain what thermal conducting insulator bushings I could or should use?
I certainly don't want to melt anything down. (again)

 

[xhdskip]

That's why I joined this forum, to ask questions,
I've already admitted I basically know nothing,
All my experience has come at a cost, where I've burned something up
or melted it down only to be replaced, and believe me, THAT gets expensive.

So I do appreciate all the help and advice.

I'll go take a picture or two of the way she looks today and post that next.

Thanks guys,
skip

 

[SeaGal]

But, the exwife got them and my first two inverters, etc in the divorce.

Sound like me.. if I got divorced I'd fight to get the panels, inverters and LiFePO4's.. he can have the sofa and air-fryer Only kidding - love him!!

 

[Hedges]

Schematics would be good too. Not sure what your diodes are connected to, now that've you mentioned 20kW.

 

[xhdskip]

Schematics would be good too. Not sure what your diodes are connected to, now that've you mentioned 20kW.

all I've got is hand drawn pictures of the wiring, well, that and the real thing of course.

 

[chrisski]

I have a back feeding problem, so I figured with the breakers and the Blocking diodes, that should solve it.

What is back feeding? Is the panel drawing power from the battery when it’s not in the sun?

Are the different PV strings so unbalanced that one is taking power instead of sending it? The blocking diodes I mention are for this.

 

[xhdskip]

I said I'd get pictures of the way she looked today. Here is some.

 

[xhdskip]

and another

 

[xhdskip]

and now the last one I got today.

 

[xhdskip]

What is back feeding? Is the panel drawing power from the battery when it’s not in the sun?

Are the different PV strings so unbalanced that one is taking power instead of sending it? The blocking diodes I mention are for this.

what is back feeding? good question, the batteries were back feeding into my second contactor (which I eliminated, hopefully, by using these Diodes).

strings unbalanced? No, as I only have 1 small solar panel at present.

 

[Hedges]

Heavy wire. Are the diodes for multiple battery banks feeding inverter?
That's the sort of thing we'd see for computer racks with hot-swappable power supplies and battery backup, where uptime is more important than efficiency.
Or alternators, which use the diodes for rectification as well as preventing backfeed. (generators use a relay, and we have to magnetize it by briefly connecting battery to coil, resulting in an electromechanical "diode".)

Don't like to see in battery path of an alternative energy system, though. High losses.

 

[xhdskip]

Heavy wire. Are the diodes for multiple battery banks feeding inverter?
That's the sort of thing we'd see for computer racks with hot-swappable power supplies and battery backup, where uptime is more important than efficiency.
Or alternators, which use the diodes for rectification as well as preventing backfeed. (generators use a relay, and we have to magnetize it by briefly connecting battery to coil, resulting in an electromechanical "diode".)

Don't like to see in battery path of an alternative energy system, though. High losses.

It's a 48V inverter, so four 12V batteries, and I figured if it's good enough for a car, it's good enough for my application.
Couldn't see the benefit of dropping down to a smaller gauge wire, less heat with the thicker cables.

High losses perhaps, but still puts out 18K instead of the potential of 20K.
Can't seem to get above that, but since the inverter is 18K, I'm good with that
(for now)

 

[Hedges]

What I don't understand is what the diodes and breakers are for.
Are the diodes carrying battery current?
What is being switched?

The breakers appear to be 2 facing one direction, 2 facing the other, ganged as a transfer switch.

Schematic would help explain.

 

[xhdskip]

What I don't understand is what the diodes and breakers are for.
Are the diodes carrying battery current?
What is being switched?

The breakers appear to be 2 facing one direction, 2 facing the other, ganged as a transfer switch.

Schematic would help explain.

The Diodes and breakers are a safety switch to stop the back feed from one power source to the other.

No, the batteries are connected to the inverter, a 48V 18K SunGold.
The switched power sources are the inverter, and a generator head.
The breakers are facing opposite directions and connected with a welding rod through the holes in the switches.
So the diodes and breakers are carrying 220V, which shouldn't be a problem for either of them
as the breakers are 220V and the Diodes are 600V and 85Amps.

 

[Hedges]

Some generators, and all of what I would call inverters, make AC. Which is why I don't understand how the diodes work for you.

Are they carrying 200VDC? 200Vrms AC? doesn't seem to be battery DC, since that is nominally 48V.
Nor PV, since you said only one panel.

I did get a Chinesium DIN rail 2-pole transfer switch off eBay. Supposedly rated 63A, but it buzzed well below that.
It seems that "63" is a designation not a current rating for some devices, and seller may have unknowingly listed that as amperage.

I replaced with a Square D QO generator interlock, swapping out its 100A and 30A breakers for 70A and 70A.

I did see a German brand of DIN rail components that could be joined to make transfer switch and various other things.
Midnight also has ganged and interlocked breakers in some of their boxes.