Solar installed then consumption apparently increased by ~60kw per month

QrizB

petalouthi said:

from smartmeter period 07/12/23-07/12/24:

• import total=1390
• export total=2575

OK, so using that info together with my previous calcuations.

• Imported: 1390
• Into battery: 1168
• Household consumption from grid: 1390-1168 = 222

and

• Exported: 2575
• Out of battery: 4919
• Household consumption from battery: 4919-2575 = 2344

So, your *actual* household consumption for the period was 2344+222 = 2566kWh.

petalouthi said:

tim_p said:

Has your annual consumption actually increased by the 720kWh?

Consumption measured from meter 07/12/21-07/12/22=2598

Consumption measured from meter 07/12/22-07/12/23=2580(includes 1st few days after installation on 22/11/23, when measured from app)

If your actual consumption for the period when you had the solar panels was 2566kWh, that's a pretty good match to the previous two years where you used 2598 and 2580kWh respectively.

Consumption from QCells app 07/12/23-07/12/24=3255
So it's increased by 675 from '23, and 657 from '22 figures

And as before, the QCells app is wildly inaccurate (or measuring the wrong thing).

petalouthi

Here are some pictures:
1. schematic from "Owner's Manual", given us by installers. There is at least one inaccuracy elsewhere in the document, so not sure how complete this is. There aren't any diagrams in the MSC certificate.
2. photo showing the installation inside the house.
3. the extra consumer unit installed with the solar system - the one to the right in photo no. 2
4,5. photos showing inverter, battery and other items on the other side of the same wall as no. 2

Qyburn
The Owner's Manual estimates an annual generation of 4385.
Generation for one year from app - 4578
Your calculation - 3785
QrizB's calculations also suggest a lower generation.
Not sure what to make of that.

QrizB. Looking at where the Generation meter is sited on schematic, it does look as though it might be measuring what you suggest.
In which case, generation is considerably lower than estimated in Owner's Manual.

If we can't trust the figures from the app for generation, or for consumption, what is the best way to calculate generation and consumption?

Have you any idea how the app is calculating generation?

QrizB

Just on the topic of estimated annual generation vs. measured, the estimate is for an average year. 2024 was not average. Pretty much everyone who's expressed an opinion over on the Green & Ethical forum has said they generated less than expected last year. It's not a surprise that you've also generated less than your estimated amount.

Hopefully 2025 will be more normal!

Qyburn

Yes the "PV Generation Meter" will register everything coming from the inverter, whether that's solar generation or from the battery. If you never charge the battery except from solar the meter will pretty much record solar production, just not accounting for battery loss.

If you charge from the grid it will overestimate.

My layout is the same and I've not found an answer. The Solaredge app gets hopelessly confused so its figures don't really help. I might see if I can replace the generation meter with that registers in both directions. Or fit another, the other way round to meter power going from the house to the inverter.

Qyburn

Qyburn said:

 I might see if I can replace the generation meter with that registers in both directions. Or fit another, the other way round to meter power going from the house to the inverter.

I think this is what's needed for a hybrid inverter like we both have. Meters import and export, and also "Net" which will therefore be the true solar production.

https://www.pluginsolar.co.uk/?product=emlite-bi-directional-kwh-meter-eca2-nv-net

Reed_Richards

I have a similar system with the battery on the DC side of the inverter.  It was installed in the days of the FiT when measuring the actual generation was necessary for you to receive any payment.  So my generation meter is bi-directional.  It defaults to the net reading but you can step through the readings for in and out, as well as various other readings.  It makes no sense to have an export meter that is not bidirectional in this configuration.  

SuzeQStan

Hi OP - this is a side reply to your mention about not charging your battery at night during the warmer months -

we charge our battery at night year round so we can get 15p per kWh for as much of our generation as possible to maximise ROI. 

Even with round trip losses on the battery this should still gain us an additional 5p per kWh we generate & export to grid

there are quite a few on here that disagree with having a solar battery but I think the tide is changing slightly as prices come down. 

 wherever you stand, if you already own the battery then it makes sense to make it pay as much as you can 😊

edit to add generated & exported to grid

petalouthi

SuzeQStan - interesting approach. We review how we do things every so often, so will consider this.

Qyburn and Reed_Richards - our Generation meter does give us "Export", "Import" and "Net". The problem has been to know how to interpret what these are telling us - if anything useful. The various comments in this thread have given us the information we probably need.

This is what we are concluding from the discussion:

1. There is probably a certain amount of inefficiency in the whole system, meaning that our actual consumption may well have increased a little, as outlined by various contributors. But this is unlikely to account for the large discrepancy.

2. We shouldn't trust the app for generation figures (and therefore not for consumption figures either) as it's probably getting confused.

3. We can probably get at generation figures using Generation meter: (Gen. meter Import-Gen. meter Export) or alternatively Gen. meter Net, although it's possible this is also getting confused.

4. We can then calculate consumption figures as: (Smartmeter import+Gen. meter Net-Smartmeter export)

5. Our generation in '24, calculated by this method, looks lower than estimated by the Owner's Manual, but this might have been due to poor weather.

We only started recording Gen meter readings systematically part way through last year, so need to do this for a few more months to be able to see whether our consumption will then more nearly match that of pre-installation years.

Thankyou to everyone who has replied - we're amazed at how much more we've learnt in a week, after months of battering at installer and QCells for info and clarification! And we hope this thread will be useful to others with similar issues.

Qyburn

petalouthi said:

Qyburn and Reed_Richards - our Generation meter does give us "Export", "Import" and "Net". The problem has been to know how to interpret what these are telling us - if anything useful. The various comments in this thread have given us the information we probably need.

The figure you need is "Net".