New solar and battery system help

Solarsquirrel132

We had a 15 panel 6kW solar system with Solax X1-Hybrid inverter and 6kW Triple Power battery system installed on December. We are on an economy 7 tariff with our energy company, so we charge the battery from the grid at night to enable us to use cheaper energy before the solar is active in the morning and on cloudier days when we aren't generating as much solar.

There are lots of things that just aren't making sense to us about the system and I'm keen to hear if others have experience or suggestions about this while we're waiting for the solar installers to send an engineer in a couple of weeks and our energy company to look into any issues with the smart meter (which is going to take 45 days...). Basically I'm losing my mind in the meantime and hoping for some ideas.

Prior to the installation, we averaged between 9-11kWh a day in usage from the grid. This never got above 12 and that was in very rare circumstances. Our SolaxCloud app is telling us we are generating and 'using' sometimes up to 9 or 11kWh of solar energy a day (not including what are usually fairly small amounts of additional solar we export). On top of this, SolaxCloud tells us we are consuming a further amount from the grid, which varies quite a bit in quantity, but at its highest is up to 10kWh. This means SolaxCloud is recording our total consumption on electricity (including solar and grid) at more than 15kWh every day and sometimes even over 20kWh. Our energy company's app shows almost no change in our usage since having solar.

Suspecting that it's something to do with the battery, and because we have had a few sunny days recently, I dropped the overnight grid charge down low (just to cover the early morning requirement before the solar gets going. That has significantly reduced the usage both on the SolaxCloud and the energy company's apps, but the figures still don't make sense with the solar generation and self-usage figures.

I've spoken to the solar installers several times and they are convinced it's to do with the smart meter incorrectly seeing solar generation and told me that the energy provider needed to 'send an update to the smart meter'. Others have told me this just isn't true. I contacted the energy provider and they were very unhelpful and simply raised a ticket to remotely look at the meter, which will take up to 45 days. Not happy with that response I went back to the solar installer, who agreed to send an engineer to check the system over, but that still isn't happening for two weeks.

In case it's useful info - we have a SMETS2 smart meter that was originally only providing monthly readings to our energy provider (we weren't aware of this until recently). It has since been changed to half-hourly.

Aside from this, does anyone know what the max charge and discharge rates are for this type of system please? I can't find the information anywhere. My understanding is that most systems have a similar charge to discharge rate, but we can discharge sometimes more than 3kW at a time from the battery and the charge rate is completely erratic. I've seen it charging at 1.7kW and sometimes at less than a kW (while sending excess to the grid, when the battery is still not full). This doesn't seem right to me, but perhaps that's normal (though hugely annoying)?

Any thoughts, suggestions, similar experiences, etc would be welcome. As I say, an engineer is coming in a couple of weeks, but we've waited so long already I just really want to have some knowledge on my side before they come.

Exiled_Tyke

I wonder whether the problem here is with the monitoring of the PV production.  The generation figures you are quotiing are very high for this time of year (I suppose they are possible depending on where you are).  My 3.3kW system does very well to do more than 2kWh a day at the moment (but it is a mainly west facing system which does have a more signficiant impact at this time of year).  If there is an over read on this then the import figures look reasonable.   In a couple of months' the PV shoul be contributing enough to see signficant reduction in import.

Petriix

You need to figure out what information is accurate. What do your half-hourly smart meter figures tell you? You might want to use something like the Bright or Loop apps if you can't see the data on your supplier's website or app. I have a 3.42kWp solar array and no battery but I can clearly see my imports dropping to zero for some 30 minute slots on sunny days, even in the middle of winter.

With the battery you should be importing zero (or close to) for much of the day and this would be obvious when looking at Bright. It should also be obvious if your battery is performing as intended. Can you provide any images of the 30 minute usage data? 

If it's SMETS2 then there's almost no chance of erroneously recording export as import on the meter itself. However, your IHD might not be so clever so definitely check your actual readings.

'No change' in usage is actually not terrible given it's the darkest, coldest part of the year. Without knowing your detailed usage patterns it's impossible to read into it but most people consume more in December and January than at any other time of year. 

Solarsquirrel132

Exiled_Tyke said:

I wonder whether the problem here is with the monitoring of the PV production.  The generation figures you are quotiing are very high for this time of year (I suppose they are possible depending on where you are).  My 3.3kW system does very well to do more than 2kWh a day at the moment (but it is a mainly west facing system which does have a more signficiant impact at this time of year).  If there is an over read on this then the import figures look reasonable.   In a couple of months' the PV shoul be contributing enough to see signficant reduction in import.

Thanks for this. All panels are only a few degrees off south with no shading, so we do have a pretty ideal situation for them. The solar installers have checked the inverter remotely and were convinced that this aspect is functioning as it should. That may of course change when the engineer comes out! On a miserable day, we might generate around 5kWh.

Solarsquirrel132

Petriix said:

You need to figure out what information is accurate. What do your half-hourly smart meter figures tell you? You might want to use something like the Bright or Loop apps if you can't see the data on your supplier's website or app. I have a 3.42kWp solar array and no battery but I can clearly see my imports dropping to zero for some 30 minute slots on sunny days, even in the middle of winter.

With the battery you should be importing zero (or close to) for much of the day and this would be obvious when looking at Bright. It should also be obvious if your battery is performing as intended. Can you provide any images of the 30 minute usage data? 

If it's SMETS2 then there's almost no chance of erroneously recording export as import on the meter itself. However, your IHD might not be so clever so definitely check your actual readings.

'No change' in usage is actually not terrible given it's the darkest, coldest part of the year. Without knowing your detailed usage patterns it's impossible to read into it but most people consume more in December and January than at any other time of year. 

Thanks for this. I can indeed see the half hourly figures showing no usage during the middle of the day. Sadly I can't post images as I'm a new user here and it doesn't let me.

While I agree that 'no change' would make sense given the time of year, it doesn't make sense because we are apparently generating plenty of solar on a sunny day like today. The issue is with the disparity between the figures. I'm beginning to wonder if it's something to do with the battery charging from the grid at night, because the figure make a lot more sense when we don't put much charge in overnight, compared to when we do.

Rheumatoid

I don't know whether your inverter / datalogger has the same problem as mine (Solis) but I think there is a bug in Solis Cloud that Charging the battery is displayed as generation. I think its still awaiting a fix.

There are some very helpful Facebook groups covering various inverters / batteries and you might get more specific advice there.

Alnat1

5kWh at this time of year on a miserable day is quite a lot. My 5.25kWp system has had plenty of days under 1kWh in Dec and Jan.

ABrass

Today my 8kW array managed 1kWh.

Pick a day with good sun and a day with terrible sun and compare the numbers for those days.

Rheumatoids suggestion makes sense, if the system is assuming that any power from the battery was solar originally (because no one thought of off peak charging) then a flat 5kW would match up closely to a 6kWh battery cycle.

For one day stop all overnight charging of the battery and see what happens.

Solarsquirrel132

Thanks for these suggestions - that's really interesting Rheumatoid, because that's exactly what I've wondered, but I didn't know there was a recognised problem. I'll look into whether mind could be similarly affected. As ABrass has suggested, I'm planning to stop overnight charging for a night and see what happens as it certainly makes a difference to the figures when I reduce the overnight charge.

Also agreed that the solar generation is sounding high. So our lowest day this month has been 5kWh and our highest has been 12kWh. Looking at the figures you've all mentioned, this does sound incredibly high, even though we do have favourable conditions (i.e. full south, no shading). I'm now wondering if we have more than one problem!

Coastalwatch

FWIW our SSE facing array of 8.85 kWp has generated 0.8, 3.1 & 2.7 kWh's respectively for the last three days accepting that other parts of the country have been doing much better. Where abouts in the UK are you!

Mikeyboy01443

I have a solax system, can you get onto the web portal and look at the graphs to interpret whats happening if you aren't sure?
The terms used in solax can be a bit confusing, but i think any electricity you use from the system, be that solar generated, or from the battery which you charged from grid, shows as self use. (Don't know if other systems do the same)
Also what mode is your system set to, should be self use.