Self consumption: making sense of meter readings.

[ToughButterCup]

I have a SOLIS  (Ginlong) inverter with its associated meter.  I am trying to find out how much of our self generated power we consume. In trying to answer the question for myself, I have tried to make sense of the SOLIS app. Frankly it's an insult to customers. Looks to me like it was designed by a first year undergrad: mostly it doesn't work. When it does, it provides a meaningless graph. There's no way of downloading and analysing the data.  So I'm going back to the raw data.

 

Here are three images from the meter  next to the inverter. ( I have uploaded images because I don't understand them - yet)

The amount of electricity imported since installed(?)

 

 .... amount exported (?) To whom?

 

... 412.8 ( below) is 413.5 less 0.7, I can see that - does that mean I have consumed 0.7 of a kWh of self-generated electricity? Or does it mean I have made a present of 0.7kWh to the National Grid

 

Can anyone point me to an online resource which will help me sort this out for myself. 

Thanks for your help.....

 

 

 

 

[ProDave]

First image is "imported power"

 

Second image is "exported power"

 

Third image is net power,  Imported - exported

 

To understand what "imported" and "exported" means, I need to know what this meter is doing?  Is it your main electricity meter? I think not, that's in the piggery isn't it?

 

So is this your "generation meter"? dedicated to the inverter?

 

If so then "export" in this case is how much your inverter has produced, and "import" is the tiny amount it consumes over night in standby when the panels are not producing anything.  So NET will be how much you have generated.

 

That's all very interesting, but it won't tell you how much you have self consumed,  for that you need to look at your supply meter.

 

Do you have a smart meter?  If so that should be able to show you your export figure.  That export figure will be what has "escaped" to the grid without you using it.

 

If you don't have a smart meter, you will probably have to fit your own export meter like I have done, I can take a picture and post it later.

[ToughButterCup]

40 minutes ago, ProDave said:

...

So is this your "generation meter"? dedicated to the inverter?

...

 

Yes.

 

40 minutes ago, ProDave said:

...

Do you have a smart meter?  If so that should be able to show you your export figure.  That export figure will be what has "escaped" to the grid without you using it.

...

 

Yes.

Here's what I think is the relevant photograph of the screen 

It's a bit counterintuitive -not to say confusing -  to see both Export and Import on the same screen

 

With typical care and attention to detail you say 

40 minutes ago, ProDave said:

....

Do you have a smart meter?  If so that should be able to show you your export figure.  That export figure will be what has "escaped" to the grid without you using it.

...

 

Yes, I do. But  I suspect smart meters are not all created equal are they?

I doubt whether that figure (1767) is the one to which you refer (export figure) because its labelled Actual Import. But the screen also shows an Export indicator.

There's a button on the side of the meter which makes the LCD display illuminate, and allows you to scroll through a series of (I think irrelevant) screens ( date, time, credit mode, meter balance, standing charge) 

 

They don't make it easy do they?

[ProDave]

No, smart meters don't seem very intuitive at all.

 

Tedious I know but can you scroll through all the different display modes on your smart meter and photograph each one?

[ToughButterCup]

Already done that Dave...

 

 

 

[ProDave]

That's not very helpful. It's not goinf to show your export.

 

I think that arrow pointing to export might be saying, that at the instant you took the picture you were exporting power, but it does not seem to want to show you how much you have exported.

[ToughButterCup]

Right. 

Wot's next then? Noo smart meter?

[ProDave]

Here is what I did.

 

I don't have and don't want a smart meter.  I just have the standard dumb single rate meter.

 

I then added my own export meter.

 

 

It is the same meter sold as a generation meter for solar PV.  But notice the mains from the suppliers meter goes to the "output" terminals of this meter, and the "input" terminals connect through the meter box No 2 and my distribution to the house and other places.

 

So this meter records what is exported back to the grid and does not register what is imported.

 

I read all my meters once a week and log energy usage.

[Roys]

Dave I presume you are using a solar diverter, how much are you finding that your solar diverter does not divert?

Are you still using a 110V tranny to feed an immersion heater?

[HerbJ]

 

I have an Enerphase monitoring system - Enerphase Envoy -  that provides this data, together with performance data on each of my PV panels/microinverters and the battery pack (if installed).  It measures export energy and power directly from the inverter systems and measures imported power via  CT on the incoming main supply at the suppliers meter.

 

Similar functionality is now available as part of more recent models of most PV diverter control systems.  My installed PV diverter, which is anold model Solarimmersion,  does not have this functionality. 

 

I also have a Export Meter, which is a requirement of my FIT contract.  I read my meters once a month.

 

I submit meter reading to my Energy Supplier one a month to ensure that my invoices and DD payments are accurate. I submit export meter readings to my FIT company every 3 months on a published schedule, to ensure that my FIT payments are paid promptly every quarter -

Edited October 21, 2020 by HerbJ

[SteamyTea]

You should have bought a decent inverter.

Now you may have to get one of the export power mangers for your inverter.

[ProDave]

16 minutes ago, Roys said:

Dave I presume you are using a solar diverter, how much are you finding that your solar diverter does not divert?

Are you still using a 110V tranny to feed an immersion heater?

No that old tranny with only on / off control was a previous experiment.

 

I am using a home made "proper" dump controller that fires a 3kW inverter on a variable power burst firing regime, similar to most of the commercial dump controllers.

 

So far in 2 years I have only exported 220kWh.  Roughly 1/3 of what the solar PV generates ends up as hot water.

[Roys]

2 hours ago, ProDave said:

 

 

So far in 2 years I have only exported 220kWh.  Roughly 1/3 of what the solar PV generates ends up as hot water.

Does this mean that your export occurs when your hot water is up to temperature and there is nowhere else to dump it except the grid.

[ProDave]

13 minutes ago, Roys said:

Does this mean that your export occurs when your hot water is up to temperature and there is nowhere else to dump it except the grid.

My immersion heater is a nominal 3kW but in practice seems to be about 2.8kW.  The PV can generate up to 3.68kW.  So if nothing else is on in the house, the PV can generate about 700W more than the immersion heater can absorb at 100% duty cycle.  That's when most accidental export occurs.  I do have the PV dump controller set to turn on a 700W panel heater that in the shoulder seasons can absorb a little heat into space heating but that gets turned off in the summer.