Watts Clever Meter.

[Beanyboy57]

Hi.
Can someone explain this graph to me? Capture4.PNG. I tried to add a larger image (90kb) but wasn't allowed.
It looks very obvious but it is not the real story.
The red is the power I am using from the grid (supposedly)
The yellow is the power from my solar panels.

Each billing period I get a rebate from the utility company for the excess power I send to the grid and have done for the last 2 years. I now have a $500 credit with them, so this indicates that I am sending power out to the grid.
I am using a WATTS CLEVER METER EW 4009. It has two sensors. One attaches around the active wire from the grid to my house just inside the meter box and the other is attached to the active from the Inverter to my meter box. It seems to be quite accurate when measuring the output from the inverter but I believe it is incorrectly measuring the flow in the active from the grid.
I think it may be that the sensor only measures in one direction or that it is measuring power moving in both directions and adding them together.
Anyone have any answers? Or better still does anyone have any solutions as I want to measure the power usage and export as accurately as possible?
Cheers
Jon

[inetdog]

Hi.
Can someone explain this graph to me? [ATTACH=CONFIG]3256[/ATTACH]. I tried to add a larger image (90kb) but wasn't allowed.
It looks very obvious but it is not the real story.
The red is the power I am using from the grid (supposedly)
The yellow is the power from my solar panels.

Each billing period I get a rebate from the utility company for the excess power I send to the grid and have done for the last 2 years. I now have a $500 credit with them, so this indicates that I am sending power out to the grid.
I am using a WATTS CLEVER METER EW 4009. It has two sensors. One attaches around the active wire from the grid to my house just inside the meter box and the other is attached to the active from the Inverter to my meter box. It seems to be quite accurate when measuring the output from the inverter but I believe it is incorrectly measuring the flow in the active from the grid.
I think it may be that the sensor only measures in one direction or that it is measuring power moving in both directions and adding them together.
Anyone have any answers? Or better still does anyone have any solutions as I want to measure the power usage and export as accurately as possible?
Cheers
Jon

Yes, the EW 4009's current clamp does not sense the direction in which the power is flowing. There are better systems that use a voltage clamp (capacitive) as well as a current transformer clamp. Those systems can detect actual wattage, allowing for Power Factor (PF) and can tell which way the power is flowing.
For your inverter output, any reverse power flow during the night will be small compared to the daily production, but for measuring the net power to or from POCO this product is worthless.

If you had a way to measure the power actually going to the loads in your house (that is by subtracting out the PV contribution from what you are reading on the service feeder conductors), then you could combine the PV production and the house loads totaled over time to figure out what the net POCO power quantity is. But most grid tie inverter connections do not allow this to be done.
If you have what is called a service-side or line-side tap connecting your GTI to the wiring between your meter and your main panel, then you can use the above technique.
If not, there is a way to run several wires through each current clamp to get a similar result. But doing this would be a job for a licensed electrician who is very familiar with PV systems.

[Beanyboy57]

If not, there is a way to run several wires through each current clamp to get a similar result. But doing this would be a job for a licensed electrician who is very familiar with PV systems.

Thanks for that. It was disappointing to see that the WATTS (not so) CLEVER meter was not really useful. It looks like I will have to by some meters that plug in to the wall sockets so that I can measure the actual wattage of each individual appliance and then subtract that from the inverter's output.

Are there any meters that can plug into a wall socket and wirelessly connect to a central digital display that reads the cumulative output from all the sockets in real time? I am guessing that there isn't.

[russ]

Are there any meters that can plug into a wall socket and wirelessly connect to a central digital display that reads the cumulative output from all the sockets in real time? I am guessing that there isn't.

Yes there are - I have to try to remember the name.

[SunEagle]

Blue Line Inovations makes a device that sits on top of your electric meter and collects kw pulses. It then can send that information to a small hand held readout showing watts used and estimated costs.

There is another unit from Blue Line called the PowerCost Monitor Gateway WIFI that will then send the data through your wireless connection to a website that keeps a record.

I currently use that equipment and send it to the myEragy website. Unfortunately that website will be shutting down in December.

Surprising I have had this installed for over a year and the "measured" energy and estimated costs is very close to what I get billed by the Utility each month. Best on line power monitor I have used.

[inetdog]

Blue Line Inovations makes a device that sits on top of your electric meter and collects kw pulses. It then can send that information to a small hand held readout showing watts used and estimated costs.

This kind of meter pulse counter often is not compatible with net metering either, and will either not count power sold or will count it as power purchased.

[SunEagle]

This kind of meter pulse counter often is not compatible with net metering either, and will either not count power sold or will count it as power purchased.

Yeah I figured as much. Just thought I would throw out a possible lead.

There is equipment that can be attached to your panel to track power usage made by E-mon D-mon. I just don't know if it can tell which way the power goes.

I have also used a harmonic analyzer meter made by Dranetz but the CT's it uses are directional so power going back out causes some funky readings.

On a side note I seem to have lost my "spell check" feature when I post so sorry if my spelling is incorrect.

[Beanyboy57]

Capture7.PNG
Can anyone explain to me what is happening in this graph? Maybe my WATTS Clever Meter is totally inaccurate at measuring even the output of the inverter?
It looks to me that my inverter is trying to match the power used in the house and this is all that it being measured by the clever meter.
Given that I know some power is being exported to the grid, this graph confuses me as to what it is actually happening with my solar panels.
All answers, suggestions are welcome, apart from comments that state the obvious such as I don't know much about electricity.