Can I exceed 500 V on EG4 3KW?

[wired1]

Hi,

Would it be ok to exceed 500 volts for my EG4 3KW inverter that says 500 volts max, if I put 2 panels that are 52.9 voc., on each of 5 sides of my Octagon roof?

I'll be way under the 5,000 watt rating (390 W each), and my thought is when the panels that face East are getting full sun, the ones facing West are getting none?

I'm also thinking of getting another EG4 3KW inverter and 20 panelstotal, so potentially 4 on each of 5 sides.

Opinions whether this is a good plan or not?

 

[Bkord]

5000 volts?

 

[G00SE]

5000v is some Jurassic park type stuff.

I think you added a zero by mistake.
52.9voc x 10 panels would be 529v.

8 panels in series would keep you below 500v even in -25 Celsius weather. It’s my understanding that input voltage is a hard limit that you don’t want to exceed unless you like smoke

 

[wired1]

5000 volts?

5000v is some Jurassic park type stuff.

I think you added a zero by mistake.
52.9voc x 10 panels would be 529v.

8 panels would keep you below 500v even in -25 Celsius weather. It’s my understanding that input voltage is a hard limit that you don’t want to exceed unless you like smoke

Oops, Thanks of course.. I'll fix it. Haha

 

[G00SE]

Oops, Thanks of course.. I'll fix it.

I was just being facetious lol. I did try to provide my 2 cents as well though

 

[glandpuck]

The 500 volts DC is the maximum voltage that your solar panels, when connected together in serial (parallel strings do not add to the voltage, only the amperage) can safely input into the MPPT charge controller without causing damage to the electronic parts of the controller. You can hook up as many panels as you want to in all sorts of directions and angles as long as through the daytime, in the coldest weather, your input voltage stays below 500 volts.

 

[wired1]

5000v is some Jurassic park type stuff.

I think you added a zero by mistake.
52.9voc x 10 panels would be 529v.

8 panels would keep you below 500v even in -25 Celsius weather. It’s my understanding that input voltage is a hard limit that you don’t want to exceed unless you like smoke

Would the West facing panels get any sun when the East panels were in full sun and vice versa?

 

[G00SE]

Would the West facing panels get any sun when the East panels were in full sun and vice versa?

Depends on the structure. In theory I would think that during the summer depending on structure or tree shading it’s possible with a high sun for all 10 to retrieve sun.
If you did 2 strings of 5 panels you’d never need to worry
I’m not qualified to go beyond napkin math though so maybe others will chime in

 

[wired1]

Depends on the structure. In theory I would think that during the summer depending on structure or tree shading it’s possible with a high sun for all 10 to retrieve sun.
If you did 2 strings of 5 panels you’d never need to worry
I’m not qualified to go beyond napkin math though so maybe others will chime in

So, is the VOC the max from each panel? I'm hoping to end up with 20 panels on 5 sides of the Octagon. The roof pitch is between 25 and 28 degrees, about the same as the latitude of my location.

Wouldn't that mean if they were facing 5 ways, none would get max exposure all day, hence none would produce max VOC?? I'm hoping someone knows the answer cause I don't....

 

[PreppenWolf]

The VOC is independent of the amount of light exposure for the most part. Basically any sunlight, even cloudy day light will max out a panel VOC.

More light = more current.

Think of your panel like a capacitor. When NOT plugged into anything the panels are still trying to shove electrons from the negative side to the positive side. When there is nowhere for the electrons to go, the panel will reach the max voltage it is capable of, this is VOC (Voltage Open Circuit). The second you allow current to flow, normally by hooking the panel to an MPPT, the voltage will drop to whatever the MPPT decides is the optimal collection voltage.

The VOC has an absolute value because MPPT is only insulated to a certain voltage, above which it will arc out, creating a short and killing the MPPT.

Max VOC normally occurs on the coldest day you have at sunrise. This is because the panels produce higher voltage at lower temperature. Your panels are coldest right before sunrise, because as soon as the sun hits them they self warm.

 

[wired1]

The VOC is independent of the amount of light exposure for the most part. Basically any sunlight, even cloudy day light will max out a panel VOC.

More light = more current.

Think of your panel like a capacitor. When NOT plugged into anything the panels are still trying to shove electrons from the negative side to the positive side. When there is nowhere for the electrons to go, the panel will reach the max voltage it is capable of, this is VOC (Voltage Open Circuit). The second you allow current to flow, normally by hooking the panel to an MPPT, the voltage will drop to whatever the MPPT decides is the optimal collection voltage.

The VOC has an absolute value because MPPT is only insulated to a certain voltage, above which it will arc out, creating a short and killing the MPPT.

Max VOC normally occurs on the coldest day you have at sunrise. This is because the panels produce higher voltage at lower temperature. Your panels are coldest right before sunrise, because as soon as the sun hits them they self warm.

OK, Thanks for that. Does it make any difference if it never gets below 60 degrees F?

 

[Joe_]

Very inexperienced solar person here. But I thought you might want to be aware of this.

As I understand it if you put all your arrays pointing in different directions under one charge controller then the output of the panels will be limited by whatever the least performing panel in the entire string‘s output is.
In the morning when the sun is in the east, the west facing facing panels will limit the output of the rest of the array. At noon the north panels output would limit of the strings output. When the sun is in the west, the east panels which are no longer facing the sun would cut down the production of the west panels. The panel that creates the least power will always be the choke point in your array. I don’t think you will get what you’re hoping for with a single charge controller.
I am hoping someone with more experience than me will comment on this. Learned this here. Hopefully I have it correct.

 

[PreppenWolf]

OK, Thanks for that. Does it make any difference if it never gets below 60 degrees F?

It makes a difference in the sense you don't have to plan for as high of a max VOC in winter.

Pull the spec sheet for your panels and find out what temp the nominal VOC was tested at.

 

[400bird]

The VOC is independent of the amount of light exposure for the most part. Basically any sunlight, even cloudy day light will max out a panel VOC.

Very true, but also an understatement. I had a panel leaning on the north (shady) side of the house with the sun side facing the house. While I was doing some testing even then it put out voltage.

To the OP, unless you are at the equator, some of the panels in those 5 directions aren't going to produce much.
Also, all the panels in a string should face the same direction at the same angle. Otherwise, production will be decreased to the level of the poorest performing panel.

 

[AZ Solar Junkie]

I would suggest putting your west facing panels in series, and your east facing panels in series, and putting the 2 together in parallel. As long as the VoC of either series set is below the limit, you're safe, and the ones not getting full sun won't hold back the output of the ones that are...

 

[Ampster]

unless you like smoke

The smoke only happens once, until you buy a new inverter or charge controller then it could happen again if you don't reconfigure. Voltage is definitely a hard limit.
The mention of 5000 volts got my attention. I think it is an easy thing for the OP to fix in the title,

 

[glandpuck]

It makes a difference in the sense you don't have to plan for as high of a max VOC in winter.

Pull the spec sheet for your panels and find out what temp the nominal VOC was tested at.

Your questions indicate that you are very new and do not yet have a high level understanding of how solar panels actually work. In cloudy conditions, they will produce electricity. In sunny colder conditions in the 20-30's they will produce the most electricity. On a dark, raining overcast day my panels will generate about 5-8% of their max if it had been a sunny day. When a panel is in the sunshine and another panel is in the shade, these panels must be connected to different charge controllers or to devices like DC optimizers so they don't produce less than the average of their outputs which is how they behave if connected together. So an East array would suffer from morning clouds and possible fog and mist, while a West facing panel usually does not have those issues. North facing panels never get direct sunshine so never optimally produce. South facing panels are best if the panels are fixed and not able to move. In any event, arrays of panels facing in different directions need to be connected to their own charge controllers to maximize output. Most of these new inverters come with 3-4 built in charge controllers.

 

[wired1]

Your questions indicate that you are very new and do not yet have a high level understanding of how solar panels actually work.

That's an understatement!

Very inexperienced solar person here. But I thought you might want to be aware of this.

As I understand it if you put all your arrays pointing in different directions under one charge controller then the output of the panels will be limited by whatever the least performing panel in the entire string‘s output is.

Thanks, I have a lot to learn....
Thanks for the input, much appreciated.

In the morning when the sun is in the east, the west facing facing panels will limit the output of the rest of the array. At noon the north panels output would limit of the strings output. When the sun is in the west, the east panels which are no longer facing the sun would cut down the production of the west panels. The panel that creates the least power will always be the choke point in your array. I don’t think you will get what you’re hoping for with a single charge controller.
I am hoping someone with more experience than me will comment on this. Learned this here. Hopefully I have it correct.

In cloudy conditions, they will produce electricity. In sunny colder conditions in the 20-30's they will produce the most electricity. On a dark, raining overcast day my panels will generate about 5-8% of their max if it had been a sunny day. When a panel is in the sunshine and another panel is in the shade, these panels must be connected to different charge controllers or to devices like DC optimizers so they don't produce less than the average of their outputs which is how they behave if connected together. So an East array would suffer from morning clouds and possible fog and mist, while a West facing panel usually does not have those issues. North facing panels never get direct sunshine so never optimally produce. South facing panels are best if the panels are fixed and not able to move. In any event, arrays of panels facing in different directions need to be connected to their own charge controllers to maximize output. Most of these new inverters come with 3-4 built in charge controllers.

OK, Do you (or anyone else) know if there's a economical way to do this (with optimizers or seperate charge controllers?)
I thought by mounting them in different directions, they would all get maximum sun for a more balanced day.
Thanks for the input, much appreciated.

Very true, but also an understatement. I had a panel leaning on the north (shady) side of the house with the sun side facing the house. While I was doing some testing even then it put out voltage.

To the OP, unless you are at the equator, some of the panels in those 5 directions aren't going to produce much.

I am very close to the Tropic of Cancer, within 1 degree.

Also, all the panels in a string should face the same direction at the same angle. Otherwise, production will be decreased to the level of the poorest performing panel.

Thanks for the input, much appreciated.

 

[ShaneC]

You can put 4 panels on each roof face in series and connect each series string in parallel. I would ignore north facing panels as they won't produce much. Let's say that leaves you with 4 strings of 4 panels so 4s4p configuration. You will want to use a combiner box to combine the strings together. That is unless your MPPT has multiple inputs, if for example it has 2 MPPT inputs then you will need to combine 2 strings together for one input and the other 2 together for the second input.

This will maximise your production during the day. As previously mentioned a string of panels connected in series will mean the current will be limited to the lowest producing panel. That is why you want them all pointing in the same direction with no shade on any of them.

When you connect them in parallel it is the lowest voltage from any of the series that is the bottle-neck but as mentioned panels in any sort of daylight will hit their operating voltage. The power produced is limited by the current.

 

[wired1]

You can put 4 panels on each roof face in series and connect each series string in parallel. I would ignore north facing panels as they won't produce much. Let's say that leaves you with 4 strings of 4 panels so 4s4p configuration. You will want to use a combiner box to combine the strings together. That is unless your MPPT has multiple inputs, if for example it has 2 MPPT inputs then you will need to combine 2 strings together for one input and the other 2 together for the second input.

This will maximise your production during the day. As previously mentioned a string of panels connected in series will mean the current will be limited to the lowest producing panel. That is why you want them all pointing in the same direction with no shade on any of them.

When you connect them in parallel it is the lowest voltage from any of the series that is the bottle-neck but as mentioned panels in any sort of daylight will hit their operating voltage. The power produced is limited by the current.

OK, it's obvious I'm a newbie so please bear with me. How can I tell what the voltage will be limited to? From something else I read, I need to make sure it's at least 10% higher than my Battery bank voltage, right?

Does putting them in 4s4p and into a combiner box allow the maximum power to then feed into the 2 inverters as they only have 1 input in each?

So, will I then be getting 100% from each string and a smaller % of the others until the sun moves to the next string?

Just trying to understand and digest all of this great info...Thanks