Definition of terms

[BENNETTSL6]

Hi
I'm trying to understand the FoxESS app statistics and graphs
It has a legend under device statistics, what do they mean?:

Under the "monthly" tab, today:
Feed-inYield 17.5
Totalield 23.80
ConsumptionYield 0.3
ChargeEnergyTotal 4.3
DischargeEnergyTotal 2.9

What is the equation, if there is one? Total yield= what + what? Is TotalYield the samee as output?

In the site overview, the following:
Output power
Feed-in power
Load power

Feed-inYield
TotalYield
LoadYield
ConsumptionYield

Is Consumption not the same as Load?

Very confused

[Dave Foster]

Don't worry, you are following a very long line of people that have been confused by this , hopefully this should fill in some of the blanks

'Power' statistics show the rate at which things are being done and are useful to see how much charge is going into your battery, what is the house load using *now*

Discharge power shows the rate at which the batteries discharge (kW from grid or solar)
Charge power shows the rate at which the batteries charge (kW from grid or solar)
Output power shows the power the inverter is using from the grid to charge the battery (kW)
Feed-in power shows the rate of export (kW)
Load power shows the power the load is taking (house consumption)

The yields are the daily/monthly/annual statistics that show how many units of power you have used, exported, charged etc..

Feed-inYield1 is the amount you have exported to the grid (kWh).
ConsumptionYield1 is grid consumption i.e everything you have imported from the grid (kWh).
DischargeEnergyTotal is the amount of discharge the battery has had (kwH)
ChargeEnergyTotal is the amount the batteries have charged (kWh)
TotalYield is all that the inverter outputs which is both solar and battery and is not at all useful when you have batteries
Load Yield from the site overview is extremely useful that is the amount your house is consuming

You can work out your solar generation from the following yields -

Solar generation = (battery charge - battery discharge - consumption Yield + Load yield + feed in yield)

Note: Edited to correct energytotals description

[graham]

I agree that Load Yield is very useful, or at least it would be if I had that parameter in the set. So is there some management function that allows it to be displayed?

As to the figure for the solar power generated, I get that displayed graphically from the inverter-charger page as Meter2Power on the lower, user configurable display. I've commented that labelling it "Meter2Power" fell a bit short of being obvious to me. But then I am now the same age as old people.

If I want solar power generated as a yield, I have to add together the TotalYeild values for the individual inverters, in my case, an S1500 and an S2000, from their statistical displays. However, I'm not sure how accurate they are, given that I think the ConsumptionYield value is consistently low; presumably due to the effects of the sampling intervals.

Graham

[BENNETTSL6]

@DaveFoster
LOL! Thank you. I don't know whether I'm more confused or not.

"ChargeEnergyTotal is the amount the batteries have discharged (kWh)"", when there is a separate figure for DischargeEnergyTotal, which is not what the batteries have discharged? Or did you mean to say charged, rather than discharged?

Thank you for the equation - I will need to read it a few more times, I think!

"Output power shows the power the inverter is using from the grid to charge the battery (kW)" - is this really only to charge the battery? Shouldn't this be zero? We were told that the batteries only charge from the solar, never from the grid.
I think I saw the output go negative at one point - why wouldn't this show up as feed in instead of negative output?

Very confused.

[graham]

If I have it right, Output Power is (nearly) the same as Discharge Power minus Charge Power.

As to charging off the grid, I can certainly set two periods when the battery is force charged. And I’m using that a lot.

I'm using forced charge a lot because my supply is on an Economy 7 tariff. So I charge the battery at 16.82 p/kWh overnight instead of 33.3 p normal tariff, but I pay 42.68 p/kWh for what I use in the day.

However, I also get 15 p/kWh for export. So if the battery is charged high in the morning, and it's a sunny day, in effect I only lose a bit more than 1.82 p/kWh for what I overcharged the battery with and then export. But if the battery is low, and it's a dull day, I will pay 25.68 p/kWh more for what I didn't import at night and have to import in the day.

I'm still learning how to control the charge level using the length of time the battery is charged for. Next, I'm going to learn about using the Max State of Charge (SoC), which sets what level the battery charges to from the grid, but does not limit how much it charges from the solar panels. However, I can't set MaxSoC from the app, and have to do it on the control panel for the inverter in the loft. So I want a value I can set and forget about.

Graham

[APfox]

TotalYield is all that the inverter outputs which is both solar and battery and is not at all useful when you have batteries

(emphasis is mine)

Most of the values I was able to figure out myself, but I couldn't get a grasp on TotalYield.
now it becomes clear why

[BENNETTSL6]

I found this video very helpful, more helpful than the one in the forum

[calu]

..
DischargeEnergyTotal is the amount of charge the battery has had (kwH)
ChargeEnergyTotal is the amount the batteries have discharged (kWh)
..

This would explain something, I wonder about. I find this terminology extremely confusing.

I had logically assumed, that ChargeEnergyTotal is the energy, that the inverter puts into the battery. DischargeEnergyTotal would be the energy, I get out of the battery. Your explanation is vice versa, sounds pretty unlogic, but it's the only explanation, how the discharge energy in my statistics can constantly be higher than the charge energy.

Is that really the definition? Who would name that like that?

[Dave Foster]

..
DischargeEnergyTotal is the amount of charge the battery has had (kwH)
ChargeEnergyTotal is the amount the batteries have discharged (kWh)
..

This would explain something, I wonder about. I find this terminology extremely confusing.

I had logically assumed, that ChargeEnergyTotal is the energy, that the inverter puts into the battery. DischargeEnergyTotal would be the energy, I get out of the battery. Your explanation is vice versa, sounds pretty unlogic, but it's the only explanation, how the discharge energy in my statistics can constantly be higher than the charge energy.

Is that really the definition? Who would name that like that?

Actually my apologies, looking at my original post I switched the terms - DischargeEnergyTotal is indeed the amount the battery has discharged, and ChargeEnergyTotal is the amount the battery has been charged.

The only problem with the totals is that they are daily (reset at midnight) so it is possible to have what seems to be more discharge than charge because it's drawing on charge that was already in the battery the day before. You really have to look at charge discharge counters over a much longer period to get a more precise answer.

[calu]

OK. In that case I have a magic battery, cause I have had that phenomenon for three months in a row now.

[TomConway]

I've just had the panels, etc installed and over the past week or so have been using the above formula to see what is being generated during these winter days. However, on quite a few days I'm getting a negative number. I stated force charging the battery overnight after a few days. My stats have been as attached

How do I get negative results from the PV?

[reef]

The calculation doesn't and hasn't ever worked for me. Today we generated 1.2kWh but the calculation gives -0.1kwh. It's due to losses inevitably being taken into account. This occurs when you force charge or discharge - basically any time you have a DC-AC or AC-DC conversion happening. It was so bad that October was over 50kWh under the real figure using the calculation for me. Some days were as low as -2kWh. Its totally useless.

It's why it's so annoying that Fox still don't give the PV production total.

[TomConway]

Thanks reef - at least I'm not going nuts. How do you know you generated 1.2kWh then?

[reef]

It can be read from the front panel of the inverter, though as you can imagine this isn't ideal so I only do it at the end of the month or days when I go up in the loft!

[Dave Foster]

The problem with the calculation is to get to solar generated it has to discount all the other measurable items, and the problem with that is there are losses involved in some of the conversions, so form example you get a loss when you convert AC to DC to charge the batteries and in the battery chemistry, likewise when you got from DC to AC to power the house and when solar is generated, on top of that is the power that the inverter itself uses (30-100Wh).

It can be between 1 to 2kw a day in combined losses, that's why you end up with the negatives as the formula unfairly lumps all of those losses into the solar generation line and those losses will appear higher at this time of year as the battery is charging more from grid and there is little solar.

As @Reef said the inverter does have an internal PV counter that says how much solar it generated that day (for the life of me my Foxess don't just expose this in the app i'll never know) - if you create a home assistant (a mini computer running a simple operating system) all of these things are visible and you can work out real time system losses as well, it's well worth the investment in time.

[Malcolm_(User)]

Hi all

i am another new user to your forum, and have some queries about the information seen or downloaded. I only had my system installed a few days ago
Notes:
I am using the 'FoxCloud 2.0' app. (the home assistant app sounds promissing, but I am not ready as yet)
My understanding is that the inverter data is uploaded to the cloud in 5 minute intervals

My queries are as follows:

1) On the phone app on the home page, swiped left, and the daily graph enlarged, you see 6 parameters against a time which is at 10min intervals
The indicated units are kW, and %. While the % indication would not be expected to vary that much in the 10 minute period, the kW indication could vary wildly. So what does this indicate. kW at the time the inverter sends the dats, the average over the 5 minute time period, the peak over the time period. Does anybody know?

2) Is there a way to download the logs via the web page, I have ot found a way as yet (bearing in mind I am a 'user')?

3) I have downloaded the logs via the app, and am trying to get my head around the parameters. So with regard the downloaded data...
a) Can I multiply Pv1Voltage/V by Pv1Current/A to get panel string 1's power?
b) Further are those figures at one point in the 5 min period, average, or peak?
c) Based on the above two queries, could I calculate kWh for that 5 min period?
d) I assume that based on the answers to the above, the same priciple applies to the other kW, and V A pair parameters?
e) The only kWh parameters are YieldToday, YieldTotal, InputEnergyTotal. I assume these are cumulative with 'Today' starting after midnight, 'Total' for all data recorded?
f) My YieldToday does show any data. What does 'Yield' and 'InputEnegy' actual mean? (sorry if this has been stated elsewhere)

I woud appreciate if anyone can exactly answer my questions
At least then I would start to eble to know how to anyse these figures
Part of the reason that I have sent this is that I am having difficulty in aligning the graphs I see on the app with activity in the house

Regards
Malcolm

[reef]

If you go into the Data Report section of the v2.0 app and then the "Custom" tab in the Reporting Method, you can select which parameters are downloaded. In there you will find things that aren't present in "Standard way". You can get PVPower (total PV Generation) and PV1 Power and PV2 Power for the generation from each individual string.

The figure is for a single point in time every 5 minutes when the inverter uploads it's data to the cloud. If you want to calculate daily PV generation, you need to get the day's data, add up all the figures and divide by 60 and then multiply by 5. The Energy stats app now does this itself aswell.

[Malcolm_(User)]

Reef

Many thanks for that.
Apologies for the delayed reply, but I had assumed I would get an email if there was an update on my post - Just seen the tick box (doh!)

I have downloaded 'all' of both types of data that is available to me, I will have a look

I have yet to look at the 'energy stats' app