Unsure if panel increase will cause overvoltage...

[thetubernoober]

So...here's my dilemma. I'm going to add a few more panels in my system which is an 18kPV.

MPPT 1 (First)
MPPT 1 (Second) *not to be confused with MPPT 2 and MPPT3 (image below)

MPPT 1 (First) and MPPT 1 (Second) are paralleled in the inverter. With a Max voltage of 600v per MPPT. Does this mean I'm maxed at a combined voltage of 600v for both MPPT 1(First) and MPPT 1(Second)? Or can MPPT 1 (First) and MPPT (Second) have 600v each?

I've attached panel specs and inverter specs.
Thanks for any help or guidance.

 

[Solar Guppy]

That is never to exceed input voltage, per channel. There is no additive effect involved between any of the mppt channels

 

[thetubernoober]

That is never to exceed input voltage, per channel. There is no additive effect involved between any of the mppt channels

Thanks. So then MPPT 1(First) and MPPT 1 (Second) are considered 2 separate channels?

 

[rhino]

Thanks. So then MPPT 1(First) and MPPT 1 (Second) are considered 2 separate channels?

No, they are the same MPPT. The two "channels" for MPPT1 simply have higher amperage capability but they are paralleled as you said. I chose to parallel at the array instead of running two separate pairs of wires for the MPPT1.

 

[rhino]

What exactly is the current panels you are using and what are you planning on adding?

 

[rogerheflin]

Thanks. So then MPPT 1(First) and MPPT 1 (Second) are considered 2 separate channels?

Current adds (for 1 and 2), but voltage for each 1/2 need to be pretty close to the same (ie under 600V each worst case). Ie put the same number and type of panels on both 1 and 2 as they are combined(current wise) into one MPPT channel that has a higher current rating than each of 3/4.

 

[TomC4306]

Parallel attached devices do not add voltages.
They add current
Best practice for parallel attached devices is to ensure the voltage of each is close to the other.

Edit- I must have been typing same time as roger

 

[Brucey]

Thanks. So then MPPT 1(First) and MPPT 1 (Second) are considered 2 separate channels?

They are the same and you'd want them to be configured identically in terms of panels. Usually it's much cheaper to parallel them out at the panels instead of running a pair of wires all the way to the inverter to parallel there.

 

[Quattrohead]

When you are paralleling strings of panels they must be the same voltage and current rating.
The maximum voltage rating is the total of one string, 600 volts Max. However you should aim for between 200 and 400 volts for best working conditions.
The other strings connected to mppts 2 and 3 can be different voltages and currents, in other words the mppts are not connected or reliant upon each other.

 

[Brucey]

May want to target 230V minimum on the low end and probably more like 250V based on recent threads.

 

[thetubernoober]

What exactly is the current panels you are using and what are you planning on adding?

All panels are identical. The issue I have is the roof design being so complicated and strings have to facing numerous different directions. I would have needed to parallel the East and West string in the inveterer but it wouldn't make any sense. So my plan is to now instead of trying to work around the roofing. I'll just add East panels to MPPT 1, West to MPPT 2, South to MPPT 3. And just use an EG4 Charge Controller for the North string and run it separately to the battery bank.

 

[Brucey]

All panels are identical. The issue I have is the roof design being so complicated and strings have to facing numerous different directions. I would have needed to parallel the East and West string in the inveterer but it wouldn't make any sense. So my plan is to now instead of trying to work around the roofing. I'll just add East panels to MPPT 1, West to MPPT 2, South to MPPT 3. And just use an EG4 Charge Controller for the North string and run it separately to the battery bank.

Sounds good, only downside I think is you may not be able to see the eg4 scc output in the eg4 monitoring portal, @Zwy should be able to advise.

 

[Zwy]

They are the same and you'd want them to be configured identically in terms of panels. Usually it's much cheaper to parallel them out at the panels instead of running a pair of wires all the way to the inverter to parallel there.

That would depend on the distance and wire size needed due to amperage. A pair of 8 AWG wires is much higher in price compared to 4 10AWG.

Sounds good, only downside I think is you may not be able to see the eg4 scc output in the eg4 monitoring portal, @Zwy should be able to advise.

It might be able to be seen as everything is EG4, might need a hub. There is a communication port on the EG4 100MPPT.

 

[thetubernoober]

That would depend on the distance and wire size needed due to amperage. A pair of 8 AWG wires is much higher in price compared to 4 10AWG.

It might be able to be seen as everything is EG4, might need a hub. There is a communication port on the EG4 100MPPT.

Thanks for the input. Not too worried about seeing the scc. My main concern is having the 18kpv on the battery bank then connecting the Charge controller to the same battery bank (both connected to the #1 battery in the bank) and then they're fighting different input charge voltages into the same battery. Not sure if that's a concern or not.

 

[Quattrohead]

Are the north facing panels even worth it ?

 

[Solar Guppy]

East and West array's can be parallel to a single mppt input without much loss of harvest as long as they are the same operational voltage. In the morning the east array will be tracked, near noon both array contribute evenly and as sun moves to west, the east array will not contribute but neither reduce the west array harvest.

 

[thetubernoober]

East and West array's can be parallel to a single mppt input without much loss of harvest as long as they are the same operational voltage. In the morning the east array will be tracked, near noon both array contribute evenly and as sun moves to west, the east array will not contribute but neither reduce the west array harvest.

This is how I have it now. West on MPPT 1 (First) and East MPPT 1 (Second). I was assuming this was causing loss in production during morningsand evenings. So that's why I wanted to put each direction on its own string. But if East and West can both work on MPPT 1 then I may just leave it and set north and south to their own strings. For MPPT 2 and MPPT 3

 

[Zwy]

Thanks for the input. Not too worried about seeing the scc. My main concern is having the 18kpv on the battery bank then connecting the Charge controller to the same battery bank (both connected to the #1 battery in the bank) and then they're fighting different input charge voltages into the same battery. Not sure if that's a concern or not.

Not sure on your setup but it won't bother anything by connecting the separate MPPT to the battery bank. I run a pair of EG4 MPPT's to a busbar and that is connected to a Lynx busbar that splits power to the inverters. I added a Chargeverter to the MPPT busbar and have run all of them together.

Here is the video how I connected it. As for charging voltage, set the MPPT to the same charging voltage the 18Kpv will use or use the communication cable. EG4/Signature Solar should be able to help in this regard.

 

[thetubernoober]

Not sure on your setup but it won't bother anything by connecting the separate MPPT to the battery bank. I run a pair of EG4 MPPT's to a busbar and that is connected to a Lynx busbar that splits power to the inverters. I added a Chargeverter to the MPPT busbar and have run all of them together.

Here is the video how I connected it. As for charging voltage, set the MPPT to the same charging voltage the 18Kpv will use or use the communication cable. EG4/Signature Solar should be able to help in this regard.

Thanks for the connection guide and the info. Clean setup by the way!

 

[thetubernoober]

Are the north facing panels even worth it ?

As of now I'm getting 30-50% of its rated output from the north. Not much but I need to squeeze every bit i can due to roofing.

 

[Quattrohead]

Get some racking under them and make them face ideal South instead, ugly as sin but you'll get far more out of them.