Re: [RE-wrenches] Off Grid Optimizers

[Kienan Maxfield]

Drake,

I am the colleague that Jay was talking about. I have long believed that a 100% 
AC coupled system was a bad idea for fully off-grid systems, primarily because 
of the black start problem, but I'm not against doing some AC coupled, and some 
DC coupled. The way the Radian works, you should be able to use any PV 
inverter, as long as you can put a Frequency-Watt grid profile on it. I haven't 
done that with the Enphase yet, but it should work great. With the SMA SB, you 
put it in "Off-Grid" mode, and then it will put out 100% of its power as long 
as the frequency is below 61 Hz, then it tapers its output linearly from 100% 
at 61 Hz down to 0% at 62 Hz. Because of this programming, the frequency will 
never go above slightly over 62 Hz

This would be stated that the curtailment starting frequency of the SB is 61 
Hz, and that the ramp-down rate is 100% per Hz, but it is fully adjustable in 
the settings. Enphase has the ability to be programmed to the following 
specifications...
The following settings define the IQ Microinverter over frequency power limit

  *   Start frequency in Hz (min 60, max 65) - I would use a minimum of 61, but 
it shouldn't really matter at all for the operation of the equipment. You 
really don't want it too high because you don't want the loads in the house to 
have too high of a frequency.
  *   Start delay in milliseconds (min 0, max 10) - this should be 0
  *   Ramp down rate in %/Hz (min 40%/Hz, max 83.33%/Hz) - this shouldn't 
really matter either. I'd go close to the high end since the Sunny Boy is 
100%/Hz and it works well.

The Radian doesn't know what the curtailment starting frequency is, nor what 
the ramp down rate is, and it really doesn't care. It just knows that when the 
voltage gets to the absorb voltage (or the float voltage after the absorb timer 
is over) then it raises the frequency until it achieves the desired effect, so 
it doesn't matter if the PV inverter has a different power throttling curve, 
the Radian can simply adjust for however that inverter reacts. You do need to 
turn on the AC coupling mode.

Basically, it should work perfectly if you program it right, and since you 
already have the DC-coupled portion to prevent the black start problem, you 
should be set.




Michael Morningstar,

Looking back, I wasn't totally clear when I was talking to Jay. The system he 
was talking about is actually grid-tied, but I took it off-grid for a good long 
while just to test the taper charging and the reactions between the Radian and 
the Sunny Boys. I wanted to ensure that it was going to work the way I thought 
it would, and it worked flawlessly, but due to the black start issue, (dark 
start), I wouldn't design an off-grid system to be fully AC-coupled.

You would be correct about Murphy if it were an off-grid system, the dark start 
issue is something I wouldn't want to mess around with, but being grid-tied, I 
don't think it will be an issue (unless doomsday shows up).

I am caring for an orphaned system nearby that is solely AC coupled using Li 
batteries, and it's off-grid. I was very much opposed solely AC-coupling 
off-grid, and this orphaned system just confirms my leeriness to the idea, but 
it was also a bad selection of equipment for this purpose. They were using the 
Schneider XW platform, and the problem there is that the XW takes too long to 
shift frequency, so while it's lagging, the PV is still putting out full power, 
and then the battery system far overshoots the absorb voltage, and the Li 
batteries shut off, and then the voltage really spikes and shut the whole 
system off. I had to just tweak the absorb voltage lower and lower until I 
found a voltage low enough that by the time the XW shifted frequency, the 
battery voltage wouldn't be overshooting the correct absorb voltage. It's a 
functional workaround that's working okay for now.




And addressing Ray's statements, I couldn't agree with you more, but here's one 
other option that (somewhat) relieves the problem...

The other thing I've observed is that if you are going to have a solely AC 
coupled system off-grid, then at least have the low battery cutout on the 
inverter significantly higher than the low battery disconnect in the batteries, 
and then get a few external 48 V battery chargers that can charge a fully dead 
battery (make sure it is the kind that doesn't look for a live voltage before 
it powers up). Then permanently wire these chargers directly to the generator 
output so that it can charge the batteries even if the inverter isn't working 
at all. This will allow the generator to revive a black start scenario no 
matter what. I think this is still inferior to having part of the array DC 
coupled, since it does require firing up a generator, but it is a functional 
workaround that I have been using on the orphaned system and it really does 
work. That being said, I think I might be able to talk him into getting some 
DC-coupled PV next spring.


Thanks,

[RE-wrenches] PG portal problems

[William Miller]

Wrenches:

Have any of you in PG & E territory had problems submitting information to PG 
through the on-line NEM portal? I have. 

I would like to start a conversation off of the wrenches platform to discuss 
this. Please contact me off the list if you want to exchange stories or ideas.

William 
___
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

Re: [RE-wrenches] Maximum Devices on Combox

[Jason Szumlanski]

I'm trying to decipher why an existing system installed by others has three
Comboxes. There are 4 XW+, 9 MPPT80, and an AGS. That sounds like 18 Xanbus
devices, so I can't figure out why they used two slaves (one for XWs and
AGS and the other for MPPT) and a third combox as master. The master has
never aggregated data properly.

I'm thinking of scrapping everything and just using a single Conext Gateway.




On Fri, Nov 1, 2019 at 11:19 AM Dave Angelini Offgrid Solar <
offgridso...@sti.net> wrote:

> Hi Jason,
>
> The limitations are basic canbus limits. xanbus is very similar. In very
> large clusters, in an XW system comboxes are master slaved to get more
> devices. Xanbus devices are also not just one type. In other words an XW+
> is 2 devices and a mppt is one device. Also the overall length of the
> wiring is critical as in canbus. Building a large system?  Time to read the
> tech notes on the Schneider website. What are you trying to design please?
>
> *Dave Angelini Offgrid Solar
> "we go where powerlines don't"
> http://members.sti.net/offgridsolar/ 
> e-mail  offgridso...@sti.net 
> text 209 813 0060*
>
> On Fri, 1 Nov 2019 07:26:59 -0400, Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
> The Conext Combox manual states:
>
> Max. number of Xanbus
> devices: Up to 20 (depending on the device type)
>
> Does anyone know what "(depending on the device type)" means? What are the
> actual limitations?
>
>
>
> Jason Szumlanski
>
> --
>
>
>
>
>
> ___
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches@lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
>
___
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

Re: [RE-wrenches] Off Grid Optimizers

[drake . chamberlin]

I agree completely that AC coupled systems are far better off if they
have a battery charging method completely independent of the off-grid
inverter. Some DC coupled solar is the best way to go. The system I'm
considering already has 2820 W of DC coupled PV. 

Drake

- Original Message -
From:
 "RE-wrenches" 

To:

Cc:

Sent:
Thu, 31 Oct 2019 19:33:11 -0600
Subject:
Re: [RE-wrenches] Off Grid Optimizers

We've discussed AC coupled many times.   Aside from the issues
Michael brought up, I need to remind that not having at least some
DC  PV charging means that when the AC system shuts down for any
reason, so does all the PV charging.  If Li+ batteries get discharged
to their low voltage shut off:  Dark Starts anyone?   With lead
acid, DC coupled PV is just as critical to keep the battery from
sulfating.

Which would you want?  

Scenario 1:Come back to trouble shoot a system shutdown,  try to
reboot, only to find no battery voltage to even test with. or 

Scenario 2:  You will have a battery that is being charged, if not
already at full charge. 

For GTB?, you decide how important this issue is,  but for Off grid
you are putting your customer in serious jeopardy without power.
Unless they have a manual bypass, the generator won't pass through to
the loads, or charge the battery either.  This is not theory, We've
had to fix these, and in some cases replace the battery bank that was
damaged after sitting dead too long. 

My previous post in favor of AC coupling was only as a supplement to
a solid DC PV system, or for module level optimization in partial
shade conditions. 

Ray Walters

 Remote Solar

 303 505-8760 On 11/1/19 1:08 PM, Michael Morningstar wrote:

  You know Murphy? That is Murphy of Murphy’s Law?  He’s gotta
just love the idea of AC coupled off-grid systems. The OB, SB, Li
system Jay described is going to keep him (Murphy) and the installer
very busy at some point. The further away the system is from
civilization, the higher the odds of chicanery and headaches. Systems
that need backup safety controls seem inherently risky too. 

 On Oct 31, 2019, at 11:06 AM, jay  wrote:

 HI Drake,

 I was just talking with a colleague the other day about a project he
did. 
 New Radian, AC coupling, lithium batteries, SB inverters.
 Everything is working just as it should with the GT inverters
tapering during AC coupling frequency shift mode.

 I would say you are fine, and while I can’t say for sure if the
Enphase will work that way, they should as they are all designed to
the same parameters rule 21. 

 I always do recommend a aux relay for backup/shutoff  should there
be some kind of issue. 

 With the Envoy you’ll be able to see that tapering as well.

 Seems like a good option for your application

 jay

On Oct 31, 2019, at 9:49 AM, Drake
 wrote:

 Hi Jay,

 Between 2160 and 2880 Watts of added array. We will be using a new
Radian.

 Drake

 At 11:49 AM 10/31/2019, you wrote:
How many watts are you adding as ac coupling?
 And presuming its an older 8k radian?

 Jay

 ___
 List sponsored by Redwood Alliance

 List Address: RE-wrenches@lists.re-wrenches.org [3]

 Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
[4]

 List-Archive:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
[5]

 List rules & etiquette:
www.re-wrenches.org/etiquette.htm [6]

 Check out or update participant bios:
www.members.re-wrenches.org [7]

 ___
 List sponsored by Redwood Alliance

 List Address: RE-wrenches@lists.re-wrenches.org [8]

 Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
[9]

 List-Archive:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
[10]

 List rules & etiquette:
www.re-wrenches.org/etiquette.htm [11]

 Check out or update participant bios:
www.members.re-wrenches.org [12]

 ___
 List sponsored by Redwood Alliance

 List Address: RE-wrenches@lists.re-wrenches.org [13]

 Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
[14]

 List-Archive:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
[15]

 List rules & etiquette:
www.re-wrenches.org/etiquette.htm [16]

 Check out or update participant bios:
www.members.re-wrenches.org [17]

MICHAEL MORNINGSTAR

       _MORNINGSTAR ELECTRIC_

PO Box 1494

Mount Shasta, California 96067

530-921-0560

CSLB 949635
  

   

___

 List sponsored by Redwood Alliance

 List Address: RE-wrenches@lists.re-wrenches.org [18]

 Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
[19]

 List-Archive:

Re: [RE-wrenches] Maximum Devices on Combox

[Dave Angelini Offgrid Solar]

Hi Jason, 

The limitations are basic canbus limits. xanbus is very
similar. In very large clusters, in an XW system comboxes are master slaved
to get more devices. Xanbus devices are also not just one type. In other
words an XW+ is 2 devices and a mppt is one device. Also the overall length
of the wiring is critical as in canbus. Building a large system? Time to
read the tech notes on the Schneider website. What are you trying to design
please? 
Dave Angelini Offgrid Solar
"we go where powerlines
don't"
http://members.sti.net/offgridsolar/ [1]
e-mail offgridso...@sti.net
[2]
text 209 813 0060

On Fri, 1 Nov 2019 07:26:59 -0400, Jason Szumlanski 
wrote:  The Conext Combox manual states:   Max. number of Xanbus
devices: Up to 20 (depending on the device type)   Does anyone know what
"(depending on the device type)" means? What are the actual limitations?   
  Jason Szumlanski  -- 

 

Links:
--
[1]
http://members.sti.net/offgridsolar/
[2] mailto:offgridso...@sti.net
___
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

Re: [RE-wrenches] Conext Inverter Grid Support Mode

[Sandra Herrera]

Jason,
The Conext XW+ in grid support, either grid support sell or self-consumption 
and during solar hours. The inverter operates in parallel with the grid but 
prioritizes renewable energy.
At the end of the day, the inverter will decide which mode to switch next based 
on the battery voltage.
Since in most cases the batteries are in reserve for a power outage, the 
inverter will go into passthrough mode.
In passthrough mode the inverter support 100% of the loads utilizing power from 
the source (grid).
In some cases, it is possible that inverter may be required to also charge 
batteries from the source provided that the charger inside the inverter is 
enabled, then the inverter will enter into charging while still supporting 100% 
of the loads with the source, this is not common, since it is preferable to 
only charge batteries with the array.
Additionally, the Conext XW+ is not a power conditioning device, which means 
that it will not clean the source, the passthrough power quality that the loads 
will see is the quality of the source.

Sandra Herrera
sandra.herr...@se.com



From: RE-wrenches  On Behalf Of 
Jason Szumlanski
Sent: Friday, November 1, 2019 5:16 AM
To: RE-wrenches 
Subject: [RE-wrenches] Conext Inverter Grid Support Mode


[External email: Use caution with links and attachments]




When the inverter is using this mode, at night or when there is not much PV 
power, are the laods seeing inverter output power or does the grid pass through 
the inverter, as in bypass the inverter directly to the loads. The manual says:

"In the morning, the PV system begins 3-stage charging of the batteries at bulk
stage and power from the grid passes through the XW+ (including XW) to the
loads."

That is not really clear. What does "passes through" mean? Does that mean the 
grid charges the batteries with the integrated charger simultaneously with the 
inverter outputting AC power, or does that mean the utility power bypasses the 
inverter and powers the loads directly while the PV system gets the batteries 
charged up?



While on the subject, and I don't think this is possible, but I have a Conext 
off-grid client that wants to have "clean" inverter power all the time rather 
than the generator power bypassing the inverters and powering the loads 
directly during battery charging. I told him it is not possible without using 
an external battery charger and eliminating the generator AC input to the 
inverter. I think I am correct on that, but I'll take any suggestions!


Jason Szumlanski

__
This email has been scanned by the Symantec Email Security.cloud service.
__
___
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

[RE-wrenches] Conext Inverter Grid Support Mode

[Jason Szumlanski]

When the inverter is using this mode, at night or when there is not much PV
power, are the laods seeing inverter output power or does the grid pass
through the inverter, as in bypass the inverter directly to the loads. The
manual says:

"In the morning, the PV system begins 3-stage charging of the batteries at
bulk
stage and power from the grid passes through the XW+ (including XW) to the
loads."

That is not really clear. What does "passes through" mean? Does that mean
the grid charges the batteries with the integrated charger simultaneously
with the inverter outputting AC power, or does that mean the utility power
bypasses the inverter and powers the loads directly while the PV system
gets the batteries charged up?



While on the subject, and I don't think this is possible, but I have a
Conext off-grid client that wants to have "clean" inverter power all the
time rather than the generator power bypassing the inverters and powering
the loads directly during battery charging. I told him it is not possible
without using an external battery charger and eliminating the generator AC
input to the inverter. I think I am correct on that, but I'll take any
suggestions!


Jason Szumlanski
___
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

[RE-wrenches] Maximum Devices on Combox

[Jason Szumlanski]

The Conext Combox manual states:

Max. number of Xanbus
devices: Up to 20 (depending on the device type)

Does anyone know what "(depending on the device type)" means? What are the
actual limitations?



Jason Szumlanski
___
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org