Maximum System Voltage

[JTSOLAR]

What exactly does the maximum system voltage of a solar panel refer too?

I

[Mike90250]

It means you can string a lot of panels in series, to make a high voltage array, for powering a Grid-Tie inverter. A year ago, 600V was the common voltage, the inverters run up to 500V input, for less amps and less loss. (20 panels in series is only 4 amps, but 550V)

I don't know why a large safety rating would be a bad thing.

[JTSOLAR]

Assuming I string a bunch of panels together in series and the string voltage is 1000V would there be a problem finding components that are rated (wire, combiners, inverters, fuses...) at 1000V?

[Mike90250]

Assuming I string a bunch of panels together in series and the string voltage is 1000V would there be a problem finding components that are rated (wire, combiners, inverters, fuses...) at 1000V?

Well, maybe, they are available, but expensive. I don't know of any inverters that need more than 500V to run, so, it's all theory so far.

[DaveC]

I'm not sure if you need to follow NEC up there in Canada, but Article 690.7 (C) limits most residential PV systems to 600V.

[lile001]

wire - rated voltage

I'm not sure if you need to follow NEC up there in Canada, but Article 690.7 (C) limits most residential PV systems to 600V.

Residential wire is rated to 600V in most cases - stick with that, the high voltage wire is unneccesary and very expensive.

[livewire1]

What is the advantage of lets say your array producing 240V or 440V? Why is 440V better? Thanks Dave

[Sunking]

What is the advantage of lets say your array producing 240V or 440V? Why is 440V better? Thanks Dave

Simple less current for a given amount of wattage.

Both Canada and USA limits the voltage to 600 volts. However no system is designed to go that high. Solar panels have a negative temperature coefficient which means the colder it gets the higher the voltage the panel produce. So in colder climates you have to use lower voltages as not to exceed the maximum Voc rating.

Just about all inverter used in grid tied systems have a maximum Voc input of 500 and some 600 volts. That means running maximum of about 375 to 480 volts on the panels @ 25 C depending on the inverter inputs

[livewire1]

So the higher the VOC on your panels, the better. Right? Ive seen them from 22 to 44 VOC. What would be the best all around panel? I have a Fronius 2500LV. When looking for panels, what are the things to look for when it comes to a good grid tie panel. Thanks

[Sunking]

So the higher the VOC on your panels, the better. Right?

Correct.

Ive seen them from 22 to 44 VOC. What would be the best all around panel?

That question is not so easily answered as it depends a bit on your location and temperature coefficient correction factor, how large the system will be in wattage, how many strings will be used, and future expansions. Its a puzzle you have to fit together once you know what the objective is.

For example if it is a small system of say 2000 watts in a warm climate, I may select a 185 watt panel and a VOC of 36 volts and string 12 panels together in series for a single string to make a 430 string at 75 degrees and leaves me plenty of wiggle room when it gets cold as not to exceed a 500 volt input limit on an inverter.

Where as in a colder climate on a fairly large system like 6000 watts with room to expand to 10,000 I may choose 200 watt panels with a Voc of 44 volts, and string 10 of them in series for a 2000 watt string, and select an inverter with a 600 volt max input.

It is all about component selection and matching the puzzle pieces up to fit.

[lile001]

What is the advantage of lets say your array producing 240V or 440V? Why is 440V better? Thanks Dave

Some inverters, such as the Sunny Boy, can operate at thier peak efficiency at voltages in the 200-400 volt range. Since they are making 240 volts AC, they don't have to work as hard to boost the DC voltage to make AC.

Now, high voltages are better only up to a point. Beyond 600V, the wire gets expensive. Beyond 500V, you start to run out of safety factor (NEC 690 requires your wire to be rated about 125% of the peak open-circuit voltage of your panel string, depending on local temperature extremes.)

There is a big difference in wire size, and expense, between 24V and 240V. Wire is ten times smaller, therefore ten times cheaper and easier to route!

[livewire1]

Ok... Sounds great, I appreciate the info.

[Richie]

High Input Voltage Charge Controller

Good Day Everyone,

Would you please advise me a battery charge controller which works together with a solar panel has the following parameters: 319 V (!) 0.288 A (92W).

Solar panel's source:

http://www.ebay.co.uk/itm/100w-Flexible-solar-panel-100-flexible-folie-/111047444981?pt=UK_Gadgets&hash=item19daf189f5

Cheers,
Richie

[inetdog]

Good Day Everyone,

Would you please advise me a battery charge controller which works together with a solar panel has the following parameters: 319 V (!) 0.288 A (92W).

Solar panel's source:

http://www.ebay.co.uk/itm/100w-Flexible-solar-panel-100-flexible-folie-/111047444981?pt=UK_Gadgets&hash=item19daf189f5

Cheers,
Richie

You can easily find a grid tie inverter that will accept that panel voltage, but I do not know of a solar CC which is designed for that high an input voltage.

[SunEagle]

You can easily find a grid tie inverter that will accept that panel voltage, but I do not know of a solar CC which is designed for that high an input voltage.

I wonder what the intent was to build a panel with such a high output voltage? Do you think they were going to some type of industrial use?