Bipolar Photovolatic arrays

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djd

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I was wondering if anybody has a drawing or wiring diagram of a bipolar photovolatic array, I understand the series circiuts and the parallel circiuts. I just cant my head around the code definition. If anybody can help me I sure would appreciate it.
 
Joethemechanic

Joethemechanic

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Dennis Alwon said:
I had the same thought when I read the title.:)

I came across this pdf. See if it helps.
Click to expand...


I use to do volunteer work with the homeless, the mentally ill, drug addicts, and alcoholics. Most of them were at least 3 of the 4. It all goes hand in hand. Even though most of what I did was mostly picking up food donations, and working in the kitchen, well,,,you still pick up a lot after a couple of years. It's hard to keep the bipolars on their meds. Some are brilliant, and the meds dull them.
 
Dennis Alwon

Dennis Alwon

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DJD, did you look at the pdf. Mark Odie was involved in it and he is one of the leading cmp members with PV. There are 350 slides or pages but there is some good info in there.
 
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djd

Senior Member
djd

djd

Dennis Alwon said:
DJD, did you look at the pdf. Mark Odie was involved in it and he is one of the leading cmp members with PV. There are 350 slides or pages but there is some good info in there.
Click to expand...

Yes and it answer my question showing me a diagram and severals others, I realy do appreciate the help, were working on a solar project for res apt. and be curious to see how they circuit the arrays.Stay good
 
Joethemechanic

Joethemechanic

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Location
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Electro-Mechanical Technician. Industrial machinery
You know there is a guy on here that engineers solar systems. I think his name is Harmmon or something like that. He would probably be the guy to talk to.
 
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BillK-AZ

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Location
Mesa Arizona
A bipolar photovoltaic array is used with inverters that require both positive and negative (with respect to common ground) inputs. While not very common, such inverters are used. Some of the earlier utility interactive inverters (Omnion for instance) used bipolar balanced DC inputs (+ & - 150V for instance).

For these inverters, half of the array is wired to produce each polarity and 2-pole DC-disconnects are used to disconnect both polarities at the same time.

The NEC defines the voltage of bipolar systems as the voltage from the highest negative to the highest positive, and uses this voltage for rating all components.

Not to be confused with transformer-less designs that use ungrounded arrays.
 
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Marvin_Hamon

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Location
Alameda, CA
djd said:
I was wondering if anybody has a drawing or wiring diagram of a bipolar photovolatic array, I understand the series circiuts and the parallel circiuts. I just cant my head around the code definition. If anybody can help me I sure would appreciate it.
Click to expand...

It's actually pretty straight forward since bipolar arrays are just a sneaky way of making a higher voltage PV array look like a run of the mill 600V PV array.

Take a string of PV modules with an even number of modules, say 8. You see this string has a positive and negative conductor and a string voltage. This is just your regular every day PV string and acts like you would expect.

Now in the middle of the string on the conductor between modules 4 and 5 attach another conductor. Now you have three conductors coming from the PV string, it's now a bipolar string. That's about how simple it is.

That middle conductor is often called a neutral conductor, I think more because no one has thought of a better name than anything else. Now you run these three conductors back to the inverter which has three terminals, a positive, a negative, and an extra terminal for that middle conductor. Now you have an operational system. You can add strings in parallel just like a monopole system.

Depending on if that middle conductor is grounded or not the NEC can either say the PV array voltage is the difference between the positive and negative conductors or the difference between the positive or negative conductor and the neutral conductor. This is the key to the sneaky part. If you ground the neutral conductor then you can have up to 600V between the neutral and one of the other conductors, and that means you have up to 1,200V between the positive and negative conductors. So I can have a 1,200V PV array but say it is only 600V which means I can use 600V listed PV modules but get the advantages of a 1,200V PV array. It's the Three-card Monte of the PV industry.

Hopefully this was helpful.
 
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