Solar Bus bar design

AJITNAYAK

Dear all.

I am new bie in solar. I wanted to know few help in designing
1) How solar bus bar for string monitoring being calculated
2) how losses are calculated
3)How current can be measured @ 500~1000v ,20A using dc shunt method.

i Google it, I got only supplier who does string combiner box.
I wanted to know what are calculation are involve.
How fuses being selected.
How load are distributed
if 24 string from input how bus bar thickness being selected with wire

BB.

Re: Solar Bus bar design

I will give it a shot--But I am not sure I am answering the questions in a useful way:

AJITNAYAK wrote: »

1) How solar bus bar for string monitoring being calculated

I am not sure what this question means at all... It sounds like you have a large central inverter and a field of solar arrays (commercial solar farm?).

Are you looking for long term monitoring or quick debugging? When working with high voltages/currents--The chance of Arc Flash and Arc Faults are high--And the danger from them. You are probably limited to commercial solutions designed for large solar farms (Solar Edge type devices, string monitoring system from vendor, etc.).

2) how losses are calculated

DC side losses are pretty simple--Just voltage drop/resistance. You can take ambient temperature into account (copper resistance rises with ambient temperature):

Power = V²/R = I²R = Voltage-Drop / Current

There should be virtually no AC/Capacitance losses on the DC side of a solar power system.

3)How current can be measured @ 500~1000v ,20A using dc shunt method.

IF the DC side of the solar power system is "ground bonded"--Then any DC Shunt in the DC Return wire will be at zero volts (relative to ground) too. UNLESS there is a return wire cut/failure.

Otherwise, you are going to need a voltage to optically isolated output monitor (tor read the 100 mVolt or whatever DC shunt voltage drop) and send that to your logging system. I am not sure how NEC/Code treats the ground bonded side of a high voltage DC power system. I would recommend you go with an isolated monitoring system for safety--If there is ever a DC return fault--You would not want the high voltage to take out the expensive monitoring system/hurt somebody.

i Google it, I got only supplier who does string combiner box.
I wanted to know what are calculation are involve.

Again--If you are looking at >600 VAC (VDC?) voltage--You are going to be looking at relatively specialized/costly equipment to do it "right".

How fuses being selected.

With fuses--You have to look at the data sheets/talk with a major fuse manufacturer:

Fuse rated current
Maximum interrupt current (big difference between breaking a 100 amp maximum source current vs 10,000+ amp max-current)
DC or AC ratings
Indicating fuses (some visible sign that the fuse has tripped)
Trip curve

How load are distributed

Not sure I understand--With a central inverter setup--The panels are multiple source (branch) circuits, and the Central Inverter is the one load.

If you have multiple sources and multiple loads--In general, it is much easier to make each an "isolated power system". I.e., not One Array and 5 GT inverter loads--But 5 separate sets array+GT inverters -- And the AC outputs are (eventually) combined into one AC output.

if 24 string from input how bus bar thickness being selected with wire

Talk with your bus bar manufacturer... It depends on alloys used, temperature ratings, how many holes break up the bus bar, which electrical codes the bus bars are designed/mfg to support, etc.

Sorry I am not more helpful at this point.

-Bill