Wire size for 150 foot run

[BrandenL]

I am putting together my first solar array system using 8 450 watt panels in series. I will be using two EG4 6500ex inverters with 2 48v Eg4 lithium batteries. I will be doing a 150’ run from the inverters to the solar panels. I purchased 150’ 8 gauge copper stranded wire. Is this size wire ok for that length with these panels or will the power loss be too great? If I calculated it correctly… the amperage will be 12.98 amps as each panel is rated for 12.98 maximum power current (IMP) and my voltage will be 277.36 volts as the panels are rated for 34.67 maximum voltage (VMP). Multiplied times 8 gives me that voltage. I have included all of the spec sheets for the equipment/materials that I am hoping to use. Thanks for any help.

 

[John Frum]

Did you forget to attach the specs?
How will you configure the panels?

 

[BrandenL]

Did you forget to attach the specs?
How will you configure the panels?

I accidentally hit post too soon. All the info is there now

 

[John Frum]

You can do 8s1p which makes things easy.
8 panels in series * 41.25 volts open circuit = 330VDC string voltage @ 13.98 amps
According to this calculator https://baymarinesupply.com/calculator
13.98 amps
300 feet round trip
330 volts
8 awg wire
= less than 1 % voltage drop.

You could stay with 12 awg and have ~2.1% voltage drop which is fine.
Since its a single string of panels you don't need any string fuses or a combiner box.
You should have a double pole single throw means of disconnect.

 

[BrandenL]

John, thanks for the info. Very helpful. And for future planning… how many of these same panels could I run in series? 11s1p? If I understand correctly wouldn’t it be limited by the inverters’ voltage input. Which in this case the max VOC is 500 per inverter which means I could hookup a maximum of 11 panels per inverter totaling 467.5 VOC. (I think I could double this since I am using two inverters) It would seem I am limited by the voltage and not necessarily by the watts as the combined wattage for 11 panels would be 4950 watts and the max pv input for the inverter is 8000 watts. Correct?

 

[Danke]

John, thanks for the info. Very helpful. And for future planning… how many of these same panels could I run in series? 11s1p? If I understand correctly wouldn’t it be limited by the inverters’ voltage input. Which in this case the max VOC is 500 per inverter which means I could hookup a maximum of 11 panels per inverter totaling 467.5 VOC. (I think I could double this since I am using two inverters) It would seem I am limited by the voltage and not necessarily by the watts as the combined wattage for 11 panels would be 4950 watts and the max pv input for the inverter is 8000 watts. Correct?

What’s the coldest temperature you get in the winter time?

If you run the numbers for say -20°F then ~10 panels would be the maximum in series.

 

[BrandenL]

What’s the coldest temperature you get in the winter time?

If you run the numbers for say -20°F then ~10 panels would be the maximum in series.

Yeah, I’m in Virginia. Coldest we got this winter was proabay 10 degrees Fahrenheit but that is an exception. I can’t remember ever getting down to -20 degrees F here. The lowest average temp here is in the month of January at 26.4 degrees F.

 

[Danke]

Yeah, I’m in Virginia. Coldest we got this winter was proabay 10 degrees Fahrenheit but that is an exception. I can’t remember ever getting down to -20 degrees F here. The lowest average temp here is in the month of January at 26.4 degrees F.

For an estimate take coldest temp:

Solar panel maximum voltage calculator - How to work out the max voltage

To get the maximum solar panel voltage you should expect from your solar panel, use our solar panel maximum voltage calculator.

gold-coast-solar-power-solutions.com.au

 

[John Frum]

I will be using two EG4 6500ex inverters with 2 48v Eg4 lithium batteries. I will be doing a 150’ run from the inverters to the solar panels.

6500 ac watts / .85 conversion factor / 48 volts low cutoff = 159.31372549 inverter amps
159.31372549 inverter amps * 2 inverters = 318.62745098 aggregate inverter amps
318.62745098 aggregate inverter amps / .8 fuse headroom = 398.284313725 fuse amps

That means 6 of those batteries in parallel to satisfy the current draw of those inverters.
Since you have 2 you can only supply ~1/3 third of the max draw.
You should also only charge them at ~100 amps aggregate.

And for future planning… how many of these same panels could I run in series? 11s1p?

8s is good, I wouldn't go higher.
These are ghetto AIO's and I would not push their mppt controllers to their voltage limits.
Also 8 has multiple factors whereas 11 is a prime number which limits your options.

If I understand correctly wouldn’t it be limited by the inverters’ voltage input. Which in this case the max VOC is 500 per inverter which means I could hookup a maximum of 11 panels per inverter totaling 467.5 VOC. (I think I could double this since I am using two inverters) It would seem I am limited by the voltage and not necessarily by the watts as the combined wattage for 11 panels would be 4950 watts and the max pv input for the inverter is 8000 watts. Correct?

Each inverter has 2 mppt controllers so you will have 4 mppts total.
I'm not clear whether the 8000 watt limit is per mppt or per aio.
To reiterate I think 8s per mppt is a good configuration especially for 2 batteries.
When/if you need more capacity. You can add batteries two at a time and put another 8s string on another mppt.

That would give you a total build out of 8 batteries(40,960 watt hours) and 32 panels(14,400 watts) which gives a ratio of 2.844444444 which is right on the money imho.

 

[John Frum]

Refining the above.
6 batteries is a full rack which is 30,720 watt hours.
3 strings of 8s is 10,800 watts
That leaves a spare mppt tracker for contingency.

 

[John Frum]

Notice the cut/paste error in the discharge section of the battery specs.
Bush league.

 

[John Frum]

Also be aware of this.

120V on the PV line?? Discussion of Will's video

@Will Prowse just did a video warning folks about 120V showing up on the PV lines. There have been several threads where people reported seeing voltage on the PV out. I always thought it was failed units, but Will reports it is normal on a lot of units. I can kinda understand if the 120V...

diysolarforum.com

Also the ATS=automatic transfer switch function in the AIO is not documented.

Finally this nugget from the manual.
"The included breaker is not a guarantee of battery protection. Size and install the correct over
current protection for conductors and battery if not included with the product." -- https://signaturesolar.com/content/documents/EG4/EG4-LL 48V-24V Manual-1.2.0.pdf

 

[BrandenL]

Also be aware of this.

120V on the PV line?? Discussion of Will's video

@Will Prowse just did a video warning folks about 120V showing up on the PV lines. There have been several threads where people reported seeing voltage on the PV out. I always thought it was failed units, but Will reports it is normal on a lot of units. I can kinda understand if the 120V...

diysolarforum.com

Also the ATS=automatic transfer switch function in the AIO is not documented.

Finally this nugget from the manual.
"The included breaker is not a guarantee of battery protection. Size and install the correct over
current protection for conductors and battery if not included with the product." -- https://signaturesolar.com/content/documents/EG4/EG4-LL 48V-24V Manual-1.2.0.pdf

Will actually made a follow up post about these inverters that they’re were one of the few that didn’t have the 120v on the pv line (see attached pic of his post)

 

[BrandenL]

Also be aware of this.

120V on the PV line?? Discussion of Will's video

@Will Prowse just did a video warning folks about 120V showing up on the PV lines. There have been several threads where people reported seeing voltage on the PV out. I always thought it was failed units, but Will reports it is normal on a lot of units. I can kinda understand if the 120V...

diysolarforum.com

Also the ATS=automatic transfer switch function in the AIO is not documented.

Finally this nugget from the manual.
"The included breaker is not a guarantee of battery protection. Size and install the correct over
current protection for conductors and battery if not included with the product." -- https://signaturesolar.com/content/documents/EG4/EG4-LL 48V-24V Manual-1.2.0.pdf

Yeah, the inverter is said to have an ATS but the lack of info on it left me with questions. I may call SignatureSolar to try to get more details on that. They did confirm in a short email response that it does have an ATS. Since I’m only starting off with two batteries, I was hoping to use the excess incoming power to directly power various loads while it is sunny using that ATS.

 

[BrandenL]

Also be aware of this.

120V on the PV line?? Discussion of Will's video

@Will Prowse just did a video warning folks about 120V showing up on the PV lines. There have been several threads where people reported seeing voltage on the PV out. I always thought it was failed units, but Will reports it is normal on a lot of units. I can kinda understand if the 120V...

diysolarforum.com

Also the ATS=automatic transfer switch function in the AIO is not documented.

Finally this nugget from the manual.
"The included breaker is not a guarantee of battery protection. Size and install the correct over
current protection for conductors and battery if not included with the product." -- https://signaturesolar.com/content/documents/EG4/EG4-LL 48V-24V Manual-1.2.0.pdf

Yeah, concerning the breaker on the battery, Will talks about this in one of his videos on this product but thanks for the reminder.

 

[John Frum]

Yeah, the inverter is said to have an ATS but the lack of info on it left me with questions.

Yes it has an ATS but the the details of its function are not published.

I may call SignatureSolar to try to get more details on that.

That sounds like a great idea.

They did confirm in a short email response that it does have an ATS.

That was never in doubt, at least as far as I am concerned.

Since I’m only starting off with two batteries, I was hoping to use the excess incoming power to directly power various loads while it is sunny using that ATS.

Excess incoming power seems a non-sequitur with regard to POCO power.

 

[BrandenL]

Yes it has an ATS but the the details of its function are not published.

That sounds like a great idea.

That was never in doubt, at least as far as I am concerned.

Excess incoming power seems a non-sequitur with regard to POCO power.

Since this is the beginner’s corner and I don’t mind admitting my ignorance. I have no clue what you said there in the last comment “excess incoming power seems a non-sequitur with regard to POCO power”. I assume POCO power is grid or POwer COmpany power. But my vocab isn’t that big. I don’t know what you mean by non-sequitur. I even looked it up in the dictionary and still can’t figure out what that sentence means ?. Are you saying that excess power has nothing to do with grid power? I don’t know what you are trying to say.

 

[John Frum]

Since this is the beginner’s corner and I don’t mind admitting my ignorance. I have no clue what you said there in the last comment “excess incoming power seems a non-sequitur with regard to POCO power”. I assume POCO power is grid or POwer COmpany power. But my vocab isn’t that big. I don’t know what you mean by non-sequitur. I even looked it up in the dictionary and still can’t figure out what that sentence means ?. Are you saying that excess power has nothing to do with grid power? I don’t know what you are trying to say.

I don't think referring to POCO="power company" power as excess makes sense in this context.
Since you will have paid up front for batteries and panels I would think you would want to put them to use, leaving POCO power consumption as the last preferred option.
Also leaving LFP batteries full is an avoidable stressor for the batteries.
Even worse if you float them full.
These AIOs have a configuration option for priority.
I think you will want SBU=solar battery utility.
See this video which explains how the ATS works in common use cases.

 

[BrandenL]

what I’m trying to accomplish is to have a poor man’s solar system. I can’t afford to buy a bunch of batteries right now… in my mind I was just going to start off with one or two and buy more each year till I get a rack full. for now, I’m just wanting to get a system going making sure that whatever I buy gives me room for growing the system. Running these two inverters in parallel allows me to charge my PHEV car (220v). That’s why I wanted two. Also, theoretically, those two inverters can have an input of 16,000 watts (I understand I may not want to run it to the max input for the inverter’s sake) and a max output of 13,000 watts (again probably not best to take it to the limit) but they give me room to grow the system over time. As far as the solar panels my thought was to put out a little more money on those… even though I don’t have a lot of battery storage, with the Automatic Transfer Switch, I could use the inverters to power a good bit of electricity in the house directly from the solar panels (which are relatively cheap in comparison to batteries). I have to have some battery power as these inverters have a pretty significant idle power draw but my hope was to use pass through power to lower my electric bill on sunny days. I’m not really interested in feeding power to the grid. I don’t believe these inverters can do that anyhow. I would have to get a hybrid system in order to do that. Anyhow, in a nutshell that’s what I’m trying to accomplish. Really, my Hope with the batteries was to use them at night to charge my car as my car is with me at work during the day. Now, I probably will be able to charge the car on solar during the summer as the days are longer but in the winter, my thought was to use the batteries when the sun has gone down.

 

[BrandenL]

I don't think referring to POCO="power company" power as excess makes sense in this context.
Since you will have paid up front for batteries and panels I would think you would want to put them to use, leaving POCO power consumption as the last preferred option.
Also leaving LFP batteries full is an avoidable stressor for the batteries.
Even worse if you float them full.
These AIOs have a configuration option for priority.
I think you will want SBU=solar battery utility.
See this video which explains how the ATS works in common use cases.

I don't think referring to POCO="power company" power as excess makes sense in this context.
Since you will have paid up front for batteries and panels I would think you would want to put them to use, leaving POCO power consumption as the last preferred option.
Also leaving LFP batteries full is an avoidable stressor for the batteries.
Even worse if you float them full.
These AIOs have a configuration option for priority.
I think you will want SBU=solar battery utility.
See this video which explains how the ATS works in common use cases.

Good video. Very helpful. Thanks for posting that.