Author Topic: Wrong Results? Does It Look Like My TED 5002-C Installation Was Done Properly?  (Read 13922 times)

hsprunt

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OK, I changed the MTU-1 setting to "Adjusted Load" and here is what I got this morning (both before the solar power system began to produce more power than the home was using and after the solar power system produced more power than the home was using):

When the solar system is producing less power than the home is using:  MTU-1 is a negative number that I interpret to be (?) the amount of power being taken from the grid.  The NET reading appears to represent gross home use of power.

When the solar system is producing more power than the home is using: MTU-1 is a positive number that equals the absolute value of the (always negative) MTU-2 (solar) power production reading added to the NET amount (amount of home power use, a positive number).

Thus, it appears to me that I still have some sort of a flip-flop in the interpretation of a reading (in this case MTU-1), depending on the relative amount of solar production (less than or great than home power use).  Here is a set of actual numbers:  MTU-2 = -1,284 Watts, NET = +668 Watts (I think this amount must be home use of electrical power), and MTU-1 = +1,952 Watts

Does this look like my problem has to do with the way the installation was done at my home power panel (and also, possibly, the proper setting of MTU-1 -- whether to LOAD or to ADJUSTED LOAD -- whichever one is actually the correct setting)?

I think that what MTU-1 and MTU-2 and NET actually mean should stay the same (whether the solar system is producing more power than the house is using or the other way round).  That does not seem to be the case in my situation.  MTU-2 is always a negative number representing solar power production, so I don't think that is a problem.  NET, I expect, is exactly what one would think it would be and thus "changes" in meaning only because the meaning of the MTU-1 reading changes, depending on whether the solar system is producing more or less power than the home is using. . .

Anyone have any thoughts?  Is there a reasonable way for me to present this problem to someone at TED to see if TED has a definitive answer/explanation for my (perceived/apparent/real) problem?

Thanks!

GAR

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110907-1417 EDT

hsprunt:

I have given you a method that would allow you to play with TED and find out exactly what it does.

I have not tried to sort out what is the structure of your system. This needs to be clearly defined.

I believe there are two possibilities.

System 1.  Power company wires terminate at a kWh meter. Call it meter 1. From this meter wires run to the main panel busbars. All loads, those things in the house that use energy and do not generate energy, derive there energy from the main panel busbars.

The solar generator is both a user and a producer of power. As a consumer of power it is very small, but measurable. Thus, creates confusion with TED, but minor. The solar system feeds into the system thru a breaker on the main panel that is plugged into the busbar.

If the solar system is dark, then meter 1 reads the power (instantaneous speed of the rotating disk)  of all loads in the house and the small amount to the solar inverter.  If the solar is producing power less than the house load, then meter 1 is rotating slower than if there was no solar power. Personally I would define this direction of power flow as positive. When solar power generated equals the house load plus the small amount of power for the inverter, then meter 1 stops rotating and there is no power flow thru the meter. Next if the solar is greater than the house load, then meter 1 should rotate backwards, and I would classify this as negative power.

If MTU1's current sensors are located on the wires between meter 1, and the main panel, then it should perform exactly as meter 1 does. If MTU2's sensors are on the wires from the solar inverter to a dual pole breaker on the main panel, then MTU2's reading should exactly match what the power flow is at the inverter AC side.

The house load should be the proper combination of MTU1 and MTU2. If things were phased as I would do it, and the system did not have this screwy absolute function messing thing up, then house load would = MTU1 + MTU2. NET, what you owe the power company, would be = MTU1.

System 2. In this case there are two power company kWh meters. Meter 1 monitors the house load. So MTU1 and meter 1 should read exactly the same. The only connection to meter 2 is the solar inverter. Meter 2 and MTU2 should read exactly the same. Meter 2 is connected to the grid on the power company side of meter 1. Now NET = MTU1 - MTU2.

Is your system type 1 or 2, and is there any disparity between where I have describe the current sensors, and your actual system layout?

.

weedeater

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Assuming that the solar inverter is connected through the main power panel on the house side of the meter (and MTU1), the first thing I would do when I see these numbers is to trip the inverter breaker.  Then I would know how much power my house is using and how much the inverter is supplying.  From that I could then make some conclusions about the numbers here.

I mean, was your house actually using 1.9kw? if it was, then with the 1.2kw of the inverter, the utility was supplying the 0.67kw.  If your house meter shows kw being used on its display, then you could confirm there since it is also totalizing the two powers.

rotus8

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HS - I believe your system is now working correctly. When you are using more than you are generating, NET should be positive - this is the TED convention, even though you might think of this as a "negative" in that you have to pay! When you are generating more than you are using, NET should be negative, indicating your power bill is going down.

MTU-2 will always be negative. The virtual "MTU-1" should always be positive, indicating house usage.

JBurgess

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I 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.


I have suggested that the TED folks do this by allowing a negitive sign in the existing option for MTU calibration. Hopefully it will show up in a future release.

hsprunt

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Thanks for the reply!

You wrote (in part):  <<I mean, was your house actually using 1.9kw? if it was, then with the 1.2kw of the inverter, the utility was supplying the 0.67kw.>>

I'm with you on the math above but, as I indicated in the example in my post, my house was appearing to be using .67 Kw, Not 1.9 Kw.  There was nothing unusual going on in the home re power use at the time and .67 Kw is a reasonable number for the base load around here (assuming both fridges happen to be running as well as my computer but with nothing else electrical of any consequence operating in the home).

I hope this response is helpful.

Thanks! 

hsprunt

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Thanks for the reply!

I should have mentioned earlier that I have just the ONE electrical meter!  Sorry!

Here are some return comments from me [within the brackets] within what you wrote re System 1:

<<System 1.  Power company wires terminate at a kWh meter. Call it meter 1. From this meter wires run to the main panel busbars. All loads, those things in the house that use energy and do not generate energy, derive there energy from the main panel busbars.

[That is my situation.]

The solar generator is both a user and a producer of power. As a consumer of power it is very small, but measurable.

[Yes -- that is the 5 or 6 watt load that the inverter requires when the solar system is not producing any power.  I had thought that the "zero" was just off slightly, but an earlier post to this thread explained the source of the 5-6 watt drain (power taken from the grid) to the inverter when the sun is down.]

Thus, creates confusion with TED, but minor. The solar system feeds into the system thru a breaker on the main panel that is plugged into the busbar.

[Yes.]

If the solar system is dark, then meter 1 reads the power (instantaneous speed of the rotating disk)  of all loads in the house and the small amount to the solar inverter. 

[Yes.]

If the solar is producing power less than the house load, then meter 1 is rotating slower than if there was no solar power.

[Yes.]

Personally I would define this direction of power flow as positive. When solar power generated equals the house load plus the small amount of power for the inverter, then meter 1 stops rotating and there is no power flow thru the meter.

[I agree -- that is when the meter's disk stops rotating.  Actually, I have a fully digital meter that displays a large amount of data, but I agree.]

Next if the solar is greater than the house load, then meter 1 should rotate backwards, and I would classify this as negative power.

[The digital meter shows a negative reading when the solar system is producing more power than the home is using. 

I just checked and here is what I saw: 

PG&E Digital Meter (for someone with Solar):  -0.70 Kw (it reads to the nearest 0.01 KW; note the minus sign, just as you said),

[Note re the following TED 5000 readings that were taken at the same time with MTU-1 is set to "Load" NOT "Adjusted Load"]

MTU-1 = +696 Watts [Which I interpret this to mean 696 watts is going TO the grid; this is consistent with the meter reading of -0.70 above, EXCEPT for the sign difference],

MTU-2 = -1,227 Watts [Solar system output, consistent with my separate reading from the solar system sensors re what the solar system was putting out at the same time MTU-2 was read], and

NET = -531 watts [Which I interpret to represent the gross home electrical power Use.

However, the +/- signs do not appear to work out right:  amount of solar production - amount of home use = amount TO grid (when, as here, solar production exceeds home use).  We get, keep the signs that TED 5000 displays above:  -1,227 - (-531) = -696 (BUT the actual reading is +696).

Here are the TED readings taken a bit later in the day -- solar system is producing more power than earlier in the day, and I think home use below went up a bit due to both fridges operating instead of just one above -- BUT with MTU-1 set to "Adjusted Load" instead:

MTU-1 = +2,410 Watts [What does MTU-1 represent???  Mathematically, it is the negative of the Solar Production number added to the Home Use number,but what is the significance of that?],

MTU-2 = -1,540 Watts [Solar Production], and

NET = +870 Watts [Home Use.]  ]

If MTU1's current sensors are located on the wires between meter 1, and the main panel, then it should perform exactly as meter 1 does.

[Based on the above examples, what you say is true, but only if MTU-1 is set to "load," not "Adjusted Load" (See the 531 watt number above for MTU-1, but why in my example above is the sign negative, - 531 watts, when it represents a USE of power when MTU-2's reading is ALSO negative when MTU-2 represents a SOURCE of power? 

When MTU-1 is set to "Adjusted Load" we get the +2,410 reading above but, physically, what does a +2,410 "Adjusted Load" amount mean in this case?]

If MTU2's sensors are on the wires from the solar inverter to a dual pole breaker on the main panel, then MTU2's reading should exactly match what the power flow is at the inverter AC side.

[It does.  The MTU-2 readings have always made sense to me and have tracked the independent values from the solar system itself re what the solar system is producing at the time.  The negative sign makes total sense to me when the solar system is operating Provided the "sign convention" TED 5000  consistently uses means that a Source of power has a Minus sign and a Use of power has a Positive sign.  However, that does not appear to be the case since in the first example above, since gross home electrical power consumption (clearly a USE of power) has a NEGATIVE sign. . . ]

The house load should be the proper combination of MTU1 and MTU2.

[I agree, but see the sign flip flop in the first example above, the one you comment upon immediately below.] 

If things were phased as I would do it, and the system did not have this screwy absolute function messing thing up, then house load would = MTU1 + MTU2. NET, what you owe the power company, would be = MTU1.

[To put what you say just above into numbers from my first example above (MTU-1 set to LOAD): House Load (-531) = +696 + (-1,227) which does = -531 but house load (USE) should be a Positive number, not a negative number, given that solar PRODUCTION is a NEGATIVE number!
>>

[Note that above solar production is always greater than home use and what we see is confusing (at least to me!).

To my mind a Further (perhaps related) complication is the "flip-flop" I mentioned in my first post to this thread {MTU-1 set to "load"}:  When the solar production number (ignoring the minus sign) is less than MTU-1 (home use, a positive number), NET is a positive number representing the power drawn FROM the grid, whereas when the solar production number (ignoring the minus sign) is greater than MTU-1, MTU-1 is a positive number and appears to represent flow TO the grid, not home use, and NET is a minus number representing home electrical use.

I have the strong belief that all this (The TED 5000 readings and their meanings) should be relatively simple to understand, but it is sure confusing to me.

Does what I posted above allow any one to set me straight and tell me if the TED sensors at my panel are correctly placed (I originally felt sure they were placed properly) and/or whether MTU-1 should be set to Load or Adjusted Load for my system to work properly, at least on the KwH side?

Perhaps an expert TED employee can help out?

Many Thanks to all concerned!

TEDSupport6

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Hsprunt, it may be best for you to call the office and speak with a technician directly about your setup to avoid any confusion: 800.959.5833.

hsprunt

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Thanks!  I am tied up for a while, but I will give that a try!

TickTock

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So.... what was the fix?  I am experiencing the exact same problem (setup1, MTU1 from panel to meter, MTU2 from breaker to solar).  When configured as loads, solar is producing 8.2kW (it's a 10kW system) and MTU1 is showing 7.2kW.  However, when I assign MTU1 as adjusted load and MTU2 as generation, it thinks the house is consuming 15.4kW with a net of 7.2kW (instead of 1kW house and -7.2kW net).

rotus8

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I think you need to reverse the polarity of your MTU1. Either swap the CTs, rotate the CTs 180 degrees (red dots the other way) or swap the MTU red and black wires. When MTU1 is set as load, an absolute value operation is done so it is always positive, masking the problem.