Author Topic: Wrong Results? Does It Look Like My TED 5002-C Installation Was Done Properly?  (Read 13923 times)

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
I am concerned that when the electrician set up my TED 5002-C installation, something was not done properly. 

I have a rooftop residential solar system and that system's output is always shown on MTU2 (zero when not operating and a negative number when the solar system is producing energy; sounds right to me so far). 

Although individual numerical readings (MTU1, MTU2, and "net") appear to make sense individually (I can cross check the MTU2 reading with a separate solar panel monitoring system showing solar system electrical energy output and can crosss-check the "net" amount reading shown on the TED 5002-C dashboard against the home digital electric meter's real time reading by going to the side of my home and reading the amount), it appears to me that there is a "flip flop" of sorts that takes place re the meaning of the MTU1 and "net" readings [That is, what those readings represent], depending on whether the value of the MTU2 reading (treated for this purpose only as a positive number) is greater than or less than the MTU1 reading (The MTU1 reading is always positive). 

When the MTU2 reading (treated as a positive number) is greater that the MTU1 reading, it appears that the "net" number on the dashboard is a NEGATIVE number and represents home use of electrical power and the MTU1 reading (a positive number) represents the flow of electrical energy INTO the grid. 

On the other hand, when the MTU2 reading (treated as a positive number) is less than the MTU1 reading, MTU1 (a positive number) appears to represent home use of electrical energy and "net" is a positive number and represents electrical energy drawn FROM the grid.

This is what I meant by a flip flop in the meanings of the MTU1 and "net" readings.

I see this sort of thing each morning some time after sunrise since, at some point as the sun rises higher in the sky, the rooftop solar system's output makes the transition from producing some electrical energy but less electrical energy than the home is using at the time (meaning the balance of the electrical energy needed is taken FROM the grid) to producing more electrical energy than the home is using at the time (meaning the surplus of electrical energy produced by the solar system over the electrical energy being used by the home is sent TO the grid).

This has been confusing to me (and perhaps still is!), but I am wondering if the situation I described above (I hope accurately!) can be explained by some sort of installation error when the TED 5002-C system was installed.  [The installer has not been a source of assistance on this point.]

I'm hoping someone on this forum can make enough sense from what I have described above to tell me if there was an installation error(s) and, ideally, what it/they is/were and how to correct it/them.

Perhaps, if there IS an error, it was made in connecting the sensors to the proper points of my electrical panel (including polarity of the loops) or possibly the error was made in the setting up the software inputs for my system.

Thanks for any help that can be sent my way! 

TEDSupport6

  • Sr. Member
  • ****
  • Posts: 291
  • Karma: +0/-0
I have one question, just to clarify: When you select MTU2 in Footprints to view solar generation only, do the readings always show up as a negative number?

PV-Skip

  • Jr. Member
  • **
  • Posts: 67
  • Karma: +0/-0
So far all your readings make sense. At least for me. ;D
(but I had to read it twice :>))

NET = Your consumption minus solar generation.
If this is a positive number, then you are consuming more than you generate.
If this is a negative number, then you are generating more than you use.

MTU1 = Your house consumption

MTU2 = Your solar generation.

You can see both, consumption and generation together on the middle window "Real Time KW Usage"
The upper number in the upper left corner is you real house consumption and the number below your solar generation.

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
Reply to First Post Replying to my original post: 

On the Dashboard, I have NEVER seen MTU2 be other than a negative number (solar production) or zero (sun is down; actually, instead of showing zero when the sun is down, a tiny value is shown -- I think it is a negative value -- something like 6 watts.  I interpreted the 6 watt reading when the reading must be 0 watts (sun is down) as a slight measurement error in MTU2 and of no real significance due to its small size.

As for what "footprints" will show re the sign of MTU2, Please tell me how to check the MTU2 reading in footprints (I know how to get around from the dashboard to graphing, history, etc., but I am not sure how to examine "footprints."

Thanks!

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
Reply to second post replying to my original post:

I believe there IS a flip-flop re what is going on.  I wrote:


When the MTU2 reading (treated as a positive number) is greater that the MTU1 reading, it appears that the "net" number on the dashboard is a NEGATIVE number and represents home use of electrical power and the MTU1 reading (a positive number) represents the flow of electrical energy INTO the grid.


[Note: in the one sentence paragraph immediately above, "net" is negative and appears to represent "home use of electrical power," whereas, in the one sentence paragraph way below {outside/below the  stuff I am writing here within the [  ] brackets), "net" is a positive number and appears to represent "electrical energy drawn from the grid."  Also, above MTU1 appears to represent the flow of electrical energy into the grid, whereas in the one sentence paragraph below MTU1 appears to represent home use of electrical energy.  Do you see the flip-flop I am talking about?  In one case MTU1 represents "the flow of electricity into the grid" whereas in the other case it represents "home use of electrical energy". . .  In one case "net" represents "home use of electrical power" and in the other case it represents "electrical energy drawn from the grid."  I would think one of the two ("net" or MTU1) would always represent, for example, "electrical energy being used in the home" {always a positive number or zero} and the other one of the two would always represent "electrical energy being put into the grid or taken from the grid, with a negative sign if net electrical energy is flowing into the grid {Since MTU2is negative} and with a positive sign if net electrical energy is flowing from the grid into my home

One other reason I think there is a flip-flop along the lines described above is that I was expecting to be able to tie the $ side of the TED energy calculations (for the identical days in my PG&E statement period) pretty closely to my monthly energy statement from PG&E, the one showing the net $ of energy produced or used in a given billing period and the net KwH of energy produced (sent into the grid) or used (drawn from the grid). 

However, that is NOT the case (never been the case all the times I have compared the two), the two are always way off from each other, even though the TED 5002-C system allows me to enter my PG&E E6 energy tariff rate structure Almost Exactly -- it's a complex one and the input structure allowed by TED does not let me track the PG&E E6 tariff rates exactly 24/7 -- the TED tariff structure is not quite robust enough -- at least as I read it -- to duplicate the PG&E E6 tariff structure in all its complexity. . . but it does allow me to come darn close to precisely duplicating the E6 tariff's structure/rates. 

In any event, the estimated net $ of energy use or production per TED for a specific number of days is WAY off the PG&E net $ of energy use or production for exactly the same days, the days in my PG&E statement period. 

FWIW, I went back through my data entry into TED to make sure I had entered the right amounts in all the right input fields and it appeared to me that I had. 

PG&E changes its E6 tariff rates -- but not the E6 rate structure -- from time to time, but that does not appear to be the source of the very large disparity I am describing.  In short, I THINK that the flip flop I described above -- due to a sensor installation error or to some non-tariff rate input error in the software set up -- TED is not getting the same net $ or net KwH results (net $ and KwH into the grid or taken from the grid during a given billing period) the way it should be able to do if everything had been set up correctly.

Thanks for all the help, guys!  This is tricky stuff for me to write about since my knowledge of EE type stuff is pretty limited!]   


On the other hand, when the MTU2 reading (treated as a positive number) is less than the MTU1 reading, MTU1 (a positive number) appears to represent home use of electrical energy and "net" is a positive number and represents electrical energy drawn FROM the grid.

rotus8

  • Sr. Member
  • ****
  • Posts: 315
  • Karma: +0/-0
First off, "Footprints" is the name of the whole web application when you attach to the TED. "Dashboard" is the first tab of Footprints.

When you set up your system, your solar is set to "generation". This setting does a negative absolute value of the power readings, so your MTU-2 readings should always be negative. The small negative number you see at night is actually a very small amount your inverter is using to keep alive when there is no generation happening; it really should be a positive number, but because of the absolute value operation, it shows up as negative. It will introduce a small error in the totals.

The usual setup of the MTU-1 in a solar setup is "adjusted load". When your solar is not generating, this should show a positive number indicating net power use. But here is where it gets confusing. With this setup, Dashboard shows the values for "NET" as the actual readings that MTU-1 sees, the combination of your house usage and the generation. It shows values for "MTU-1" but in reality this is the actual MTU-1 information with the MTU-2 subtracted out so it indicates a "virtual MTU-1" showing just the house usage. I believe this is also done with an absolute value function to make it always positive, but I am not certain about that.

If the NET indication is negative at night when you are not generating, the polarity of your MTU-1 installation needs to be reversed. This can be done in one of three ways: 1) Rotate both of the CTs 180 degrees on their wires. 2) Swap the CT locations. 3) Exchange the MTU red and black wires; these are all equivalent.

The absolute value calculations performed at various steps can be really confusing.

jrwalte

  • Jr. Member
  • **
  • Posts: 60
  • Karma: +0/-0
You should post a screenshot of your footprints System Layout tab under the Settings Wizard so we can see how your 2 MTUs are configured. What we need to see is the MTU Configuration section.

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
Re the set up of my MTUs, I (think I) went to the screen you requested and here is what I found (in lieu of a screen shot, something I am not sure I know how to do):

MTU1 ===> "Load"

MTU2 ===> "Generation"

I THINK these are the proper standard settings in my case (since I have a solar system installed on my roof)

I hope the above information is what you asked for!

Thanks!

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
Thanks for the reply below!

Please see some return comments of mine within the brackets, [  ].

-------------------------------------------------------------------
First off, "Footprints" is the name of the whole web application when you attach to the TED. "Dashboard" is the first tab of Footprints.

[OK, Thanks!  I thought it was probably something like that, but was not sure!]

When you set up your system, your solar is set to "generation".

[Yes -- see my other reply today in which I confirmed that the solar system -- MTU2 -- is set to "generation" and that MTU1 is set to "load."  I believe these are the "standard" settings (???) for someone using TED 5000 who has a photovoltaic solar system on his roof.  I sent in my original question on this thread since I was concerned about what I took to be a "flip-flop" that made me think the electrician who set up the TED 5000 for me might have made a mistake re my electrical panel and/or the software set up for the TED 5000 when he did the installation.]

This setting does a negative absolute value of the power readings, so your MTU-2 readings should always be negative.

[They are, except for the small negative reading when the solar system is "asleep."  See below.]

The small negative number you see at night is actually a very small amount your inverter is using to keep alive when there is no generation happening; it really should be a positive number, but because of the absolute value operation, it shows up as negative. It will introduce a small error in the totals.

[OK!  That makes total sense to me -- I had thought it was simply a failure for things to be "zeroed" properly.  I am pretty sure the reading in question is a minus 0.006 KW which, if I understand you correctly means that my inverter is drawing 6 watts of power while on standby when the sun is down.]

The usual setup of the MTU-1 in a solar setup is "adjusted load".

[As indicated above, when I checked, I see that my MTU-1 setting is to "load". . .  Should I change the software setting for MTU-1 to "adjusted load" from "load?"  Will that change, alone, fix the problem I think I have (assuming I DO have a problem)? See additional responses from me to you later comments below. . . ]

When your solar is not generating, this

["this" assumes MTU-1 is set to "adjusted load," right?  I am set and have always been set to "adjusted load."]

should show a positive number indicating net power use. But here is where it gets confusing. With this setup, Dashboard shows the values for "NET" as the actual readings that MTU-1 sees, the combination of your house usage and the generation. It shows values for "MTU-1" but in reality this is the actual MTU-1 information with the MTU-2 subtracted out so it indicates a "virtual MTU-1" showing just the house usage.

[This makes sense to me in that I think my TED system should show me and work with two fundamental values:  What amount of electrical power my solar system is generating (MTU-2, no problem, it appears to be doing just that with a negative value -- meaning energy is being generated by me from the solar system -- when the solar system is operating) AND what amount of electrical power my home is using (presumably shown as a positive number, indicating USE of power).  To be consistent, the net would be power sent TO the grid (a negative number) and power taken FROM the grid (a positive number) and there should be no flip-flop in definitions depending on whether solar power output is greater than or less than the amount of power being used in the home.] 

I believe this is also done with an absolute value function to make it always positive, but I am not certain about that.

If the NET indication is negative at night when you are not generating,

[I will check on this tonight and let you know soon.  Perhaps once we know the answer to that, and knowing that MTU-1 is currently set in my case to "Load" and not "Adjusted Load" we can decide exactly what changes -- software setting and/or at my electrical panel -- need to be made so that, assuming I properly enter my PG&E E-6 tariff values, going forward my TED data output (net KwH and net $) will track (within measurement errors) my PGE month "Net Energy Metering Electrical Statement" values (for new KwH and net $)

the polarity of your MTU-1 installation needs to be reversed. This can be done in one of three ways: 1) Rotate both of the CTs 180 degrees on their wires. 2) Swap the CT locations. 3) Exchange the MTU red and black wires; these are all equivalent.

[I will hold on making any hardware or software changes until I can get back to you re the answer to your question above re what my MTU-1 shows when the solar system is not operating.]

The absolute value calculations performed at various steps can be really confusing.

[It sure has been confusing me -- I think the individual numbers I am getting through TED 5000 make sense, but the netting of them and the interpretation of them varies depending on whether solar power generation exceeds or is less than home power use at a given moment in a 24 hour period. . .

Thanks a lot for all you help!  I will get back sometime tomorrow with confirmation of my MTU-1 sign (plus or minus) when the sun is down.]
--------------------------------------------------------------

rotus8

  • Sr. Member
  • ****
  • Posts: 315
  • Karma: +0/-0
I am a little confused by something. At one point you say
Quote
As indicated above, when I checked, I see that my MTU-1 setting is to "load"
at another point you say
Quote
"this" assumes MTU-1 is set to "adjusted load," right?  I am set and have always been set to "adjusted load."

I am quite sure you want MTU-1 to be set to "adjusted load".

GAR

  • Full Member
  • ***
  • Posts: 131
  • Karma: +0/-0
110905-1728 EDT

In my opinion there is no reason to take the absolute value of any of the MTU values. Inherently the MTU has the ability to, and maybe actually does output a signed value for power no matter what is the setup. I know the Cirrus chip can do it. I do not know where in the system the absolute value function is been applied. Is the absolute function performed inside the MTU box or after the data gets to the Gateway?

If you have the signed values available, then all that has to be done is write a simple equation for the power at whatever point you want to know the value. Personally I would make power from the power company positive. The same for solar and wind. So when any of these sources are power producers their values would be positive. Then any necessary sign change would be introduced in the equation to produce the desired result.

I truly do not know how TED is processing some of this data based on comments and problems that appear in various threads. There seems to be some conflicting information. It seems to me that one should be able to use the power display in the Dashboard to view any single MTU including its sign information, and the combination from any equation. Much like I would use a voltmeter to check a circuit. No matter where I look at data in the system a graph, the Dashboard, any history, export, or anything else the data for that item should be the same including sign.

How would TED handle a DTE setup where solar connects to the grid thru its own meter, and a windmill also connects thru its meter to the grid, and solar plus wind power returns to the house thru the power company side of the main meter. The main meter measures power from the grid or any other parallel source to the power company side of the meter, and also this is identical to the load in the house. The solar and/or wind power goes thru its meter directly to the grid. So net power from the power company at the service drop is equal to the main meter minus solar and wind if present.

This whole operation could be simple, accurate (correct), and flexible. That it is not at present. No wrong values because of the absolute value function.

.
« Last Edit: September 14, 2011, 10:41:27 PM by TEDSupport6 »

rotus8

  • Sr. Member
  • ****
  • Posts: 315
  • Karma: +0/-0
I believe that the absolute value function was put in place because installing the CTs and MTU has a 50-50 chance of giving the polarity desired; simple physics. In most installations, at least a few years ago when solar and other home generation was less prevalent, this usually gives the correct answer and reduces installation questions.

This is no longer the case and the absolute value now gives more problems than it solves. In my opinion, there should be a software option in setup to flip the sign of the MTU reading, a much easier operation than flipping CTs or swapping wires. Also a more open interface with an equation builder to combine the MTU values (possible as a new option so legacy users are not impacted) would also greatly enhance usability.

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
I checked after sundown last night and my MTU-1 sign was positive and equal to the net house load (except for the -5 or -6 watts that MTU-2 shows when the sun is down; the reason for this -- inverter power needs when the sun is down -- was explained to me previously). 

As indicated previously, the installer set MTU-1 to "load" and MTU-2 to "generation" when he was here setting up the various connection to my house electrical power panel. . .

So, the question is:  Given my initial posting re what I think my problem is (what I termed the flip-flop depending on whether the absolute value of the MTU-2 reading is less than or greater than the MTU-1 reading) and the subsequent discussion, what step(s)/Change(s) do folks believe I should I take/make to get my TED 5000 to properly track and record my gross home energy/$ use  and amount of energy/$ taken from/provided to the grid throughout a 24 hour period?  [Assuming I have properly entered the values for my E-6 PG&E Tariff and that the TED system allows me to enter the entire tariff schedule in sufficient detail -- which it does for all winter season rates and almost does for all summer season rates)?

MTU-2 always reads negative (as I think it should) when the solar system is producing power. 

Thanks to all of you for your help and comments! 

rotus8

  • Sr. Member
  • ****
  • Posts: 315
  • Karma: +0/-0
Your CTs are oriented correctly. You need to change MTU-1 mode to "adjusted load".

hsprunt

  • Newbie
  • *
  • Posts: 16
  • Karma: +0/-0
Thanks!  I will make the change to Adjusted Load and see if what happens makes sense -- both when house use is less than solar generation and when house use is greater than solar generation.  I'll let you know what I see after the change once I have a chance to check out the results. . .