Guidance with off gird setup EG4 6500k, LP4 batteries and Canadian Solar panels

[zorrotm]

Hi, I have purchased 32 440w bifacial Canadian Solar panels, which I will link below. I also purchased 2 EG4 6.5kw inverters, and 6 x EG4 Lifepower4 48v 100ah batteries server rack.

I intend to install the panels on the ground using the EG4 racks, positioning them approximately 150 feet away from the house where the inverters will be located. I'm relatively new to solar energy and have a few questions. Any guidance you can provide would be greatly appreciated.

Are the EG4 6500K inverters bad?
Firstly, I've come across several complaints in various forums regarding the EG4 6500k inverters malfunctioning and failing. Should I be concerned about the reliability of these inverters? Or am I being paranoid?

What gauge wire should I use?
Due to the distance involved, my plan is to connect the panels in series to keep the amperage low and allow for the use of smaller gauge wire. However, I'm uncertain about the appropriate wire gauge to use. I've used online calculators, but the results seem inconsistent and don't seem to account for the panels being connected in series instead of in parallel. I initially thought I needed 8 AWG wire, but Signature Solar said 10 AWG would have only 1% loss. Does that sound right? And should I use PV wire such as: https://www.wireandcableyourway.com/solar-photovoltaic-pv-wire
I am reading some say to get 7 stranded or 13 stranded wire. And what conduit would you recommend putting it in?

Does inputs in inverters need to be equal for each inverter and across multiple inverters?
My plan is to run 6 panels in series, which would require an additional inverter since each inverter has two inputs and I would need more than four inputs. However, this would result in an odd number of panels on one input, as 32 panels divided by 6 is not an even number. Is it acceptable to connect 6 panels in series to each input for two inverters, totaling 24 panels, and then use the third inverter to connect 4 panels in series to each input, for a total of 8 panels? Or will this imbalance something?

My original goal was to run 8 panels in series per input so the two inverters would handle all 32 panels but I am being told by other people with solar that the inverters won't handle all the power the panels will produce?? I guess if the bifacial was to produce well maybe this is possible idk. Two EG4 inverters would offer 16kw input. 32 x 440w panels is 14kw. If bifacial was producing 20% then it would equal 16.896kw but this seems unlikely as I am in Upstate New York. Thank you for any help

Solar Panels stats: https://www.canadiansolar.com/wp-co...dian_Solar-Datasheet-BiHiKu_CS3W-MB-AG_EN.pdf

 

[pvgirl]

First 8 in series across all 4 total MPPTs on both inverters is an acceptable configuration, unless it gets below -87f in your part of upstate, Here's a bunch of values I calculated for your setup.

Configured		Watts	Imp Max	Isc Max	Voc Max	Vmp Min	Vmp Max
Series	8​	3520​	12.14	11.8	462	266	365

At the voltages a distances we are dealing with here voltage drop on wires from the PV panels to the inverters isn't going to matter, although my calculations put it being 3% or less. Based on ampacity calculations you only need to use 12 AWG wire, even derating for 8 current carrying conductors in a conduit also still allows 12AWG. You will need to use PV wire until you enter conduit, then you can switch to thhn/thwn-2 wire. Don't forget you need a ground wire running with your PV circuits for bonding the metal frames, and mounts together. Ground wire needs to be 6 AWG when outside of conduit, and can be 12 AWG when in conduit. PVC conduit is widely available and is a good choice for your under ground runs. You can use schedule 40 PVC conduit underground, and switch to schedule 80 PVC or metal conduit above ground. Conduit size will depend on wire sizes and quantity.

The 8 in series configuration is balanced no no worries there.

Given real world conditions it will be rare to get max production, and that much bifacial gain so you well within the limits of your inverters.

 

[Adam De Lay]

Are the EG4 6500K inverters bad?

In my experience it really seems to be 50/50. You'll have some with no issues whatsoever and others that seem to have constant problems. Some of it has to do with usage, some of it with installation, others just have hardware failures.

What gauge wire should I use?

The gauge is gonna be based on the configuration of your panels. How many panels in series/parallel? You then take the voltage, amperage and distance based on each string (not just one panel) and then put that into a calculator. I've been using the Southwire Voltage Drop app on my phone and haven't been disappointed.

If I'm looking at the correct stats, you could have 8 in series and be near 328v per string. 10awg would be more than sufficient.
Edit: 389v per string, not including temp coefficient

Does inputs in inverters need to be equal for each inverter and across multiple inverters?

You don't have to have equally matched strings on each pv input of the inverters. I had 4 strings and each one was different.

My original goal was to run 8 panels in series per input so the two inverters would handle all 32 panels but I am being told by other people with solar that the inverters won't handle all the power the panels will produce?? I guess if the bifacial was to produce well maybe this is possible idk. Two EG4 inverters would offer 16kw input. 32 x 440w panels is 14kw. If bifacial was producing 20% then it would equal 16.896kw but this seems unlikely as I am in Upstate New York. Thank you for any help

The 440W is perfect conditions, which really doesn't happen very often. Even if you had 20% additional from bifacial, you're looking at just over 4.2kw from a string of 8 in series. The inverters can handle up to 4kw on each mppt tracker, so you would only be clipping 200w...if you had perfect conditions. I would just use the 8 panels in series.

 

[zorrotm]

First 8 in series across all 4 total MPPTs on both inverters is an acceptable configuration, unless it gets below -87f in your part of upstate, Here's a bunch of values I calculated for your setup.

Configured		Watts	Imp Max	Isc Max	Voc Max	Vmp Min	Vmp Max
Series	8​	3520​	12.14	11.8	462	266	365

At the voltages a distances we are dealing with here voltage drop on wires from the PV panels to the inverters isn't going to matter, although my calculations put it being 3% or less. Based on ampacity calculations you only need to use 12 AWG wire, even derating for 8 current carrying conductors in a conduit also still allows 12AWG. You will need to use PV wire until you enter conduit, then you can switch to thhn/thwn-2 wire. Don't forget you need a ground wire running with your PV circuits for bonding the metal frames, and mounts together. Ground wire needs to be 6 AWG when outside of conduit, and can be 12 AWG when in conduit. PVC conduit is widely available and is a good choice for your under ground runs. You can use schedule 40 PVC conduit underground, and switch to schedule 80 PVC or metal conduit above ground. Conduit size will depend on wire sizes and quantity.

The 8 in series configuration is balanced no no worries there.

Given real world conditions it will be rare to get max production, and that much bifacial gain so you well within the limits of your inverters.

Thanks for the reply. You said can switch wire... Is there any benefit to switching to thhn thwn-2 wire other than cost. We live in NY, it doesn't get extremely cold or hot here. It can drop below zero but not to -40 or something crazy so temperature isn't a good reason for us to choose a specific wire. If it is all the same I kind of would prefer to just run PV wire the entire way.

If it will be 3% or less loss that is fine by me for sure.

 

[pvgirl]

Thanks for the reply. You said can switch wire... Is there any benefit to switching to thhn thwn-2 wire other than cost. We live in NY, it doesn't get extremely cold or hot here. It can drop below zero but not to -40 or something crazy so temperature isn't a good reason for us to choose a specific wire. If it is all the same I kind of would prefer to just run PV wire the entire way.

If it will be 3% or less loss that is fine by me for sure.

Cost and wire size are the 2 reasons to change form PV wire to THHN/THWN, PV wire has thicker insulation and will require larger conduit then thhn. But there is no reason you couldn't run PV wire the whole way.

 

[zorrotm]

In my experience it really seems to be 50/50. You'll have some with no issues whatsoever and others that seem to have constant problems. Some of it has to do with usage, some of it with installation, others just have hardware failures.

The gauge is gonna be based on the configuration of your panels. How many panels in series/parallel? You then take the voltage, amperage and distance based on each string (not just one panel) and then put that into a calculator. I've been using the Southwire Voltage Drop app on my phone and haven't been disappointed.

If I'm looking at the correct stats, you could have 8 in series and be near 328v per string. 10awg would be more than sufficient.
Edit: 389v per string, not including temp coefficient

You don't have to have equally matched strings on each pv input of the inverters. I had 4 strings and each one was different.


The 440W is perfect conditions, which really doesn't happen very often. Even if you had 20% additional from bifacial, you're looking at just over 4.2kw from a string of 8 in series. The inverters can handle up to 4kw on each mppt tracker, so you would only be clipping 200w...if you had perfect conditions. I would just use the 8 panels in series.

So I guess I will stick with the inverters and hope for the best. Sounds like it's mainly software or setup issues then.

Thanks for your input

 

[zorrotm]

I have another question. Maybe a silly question. I understand that parallel adds up amps and series adds volts. So if I run series-parallel how does it work? If I run 4 panels in series and parallel them with 4 in series does this equate to the same total amps as if they were running in parallel or does it simply double the amps if they were running in series? Hope that makes sense. Thanks

 

[pvgirl]

I have another question. Maybe a silly question. I understand that parallel adds up amps and series adds volts. So if I run series-parallel how does it work? If I run 4 panels in series and parallel them with 4 in series does this equate to the same total amps as if they were running in parallel or does it simply double the amps if they were running in series? Hope that makes sense. Thanks

With 2 strings in parallel that would double the amps, volts would be 4 times the voltage of 1 panel.

 

[Adam De Lay]

Rounding your panel numbers to make things easier: 50Voc and 12a

- 4 in series would be 200Voc @12a.
- If you then paralleled two of the same series strings together, you would have 200Voc @24a.

 

[pvgirl]

2 or more of those panels in parallel does exceed the current limit of your inverters(18a)

 

[timselectric]

2 or more of those panels in series does exceed the current limit of your inverters(18a)

I think that you meant to say parallel?

 

[pvgirl]

I think that you meant to say parallel?

Yup fixed