New solar panels and a PV Grid Tie inverter charging 4 Li-ion batteries - Why is my meter still clocking similar usage? Have my batteries been installed correctly?

No worries, @Blastoise186 - I’ve been exchanging PMs with @dnshorto today already, and he’s not with OVO.

Personally, I think this is beneficial. There’s some generic background issues to discuss here.

@Tim_OVO - as he hasn’t got a meter running backwards, can we move this to a new Discussion Topic please? I’d suggest Solar Panels and Storage Battery with Grid Connection because we’re about to have lots more traffic on that Topic when the next Storage Trial commences.

I’d like to put together a couple of diagrams to show the two main methods of doing a grid-connection with PV Panels and Home Battery Storage, but today I’m on my roof installing more PV cables whilst it isn’t yet raining!

In the meantime, can we have some further detail of your particular installation please @dnshorto ?

Is your house connection single-phase or 3-phase?

What is the power of each solar panel? Having as many as 28 is very unusual!

Are they all “south-facing” or are they split into an “East-group” and a “West group”?

Thanks @Tim-OVO. I was looking for a suitable thread.

The solar panel installers gave no information about any limits to panel numbers, or official permissions that needed to be granted. I was unaware of this until today. Although keen on the “green” aspect of solar my primary motivation was preparation for extended power outages given the reportedly parlous state of the UK’s generating capacity, and having experienced them elsewhere. `Hence the battery capacity and maximised panel array. That provision may now be in place, but I was also hoping for reduced power bills as a welcome by-product! The :”diagrams to show the two main methods of doing a grid-connection with PV Panels and Home Battery Storage,” which you mention sound like a very useful resource and I look forward to learning more please. (Maybe re-educating the installation team too!)

I have looked through the paperwork provided by the solar panel people, there doesn’t seem to be any reference to a Grid-connection certificate, but maybe it is yet to be provided as the job was only finished last Friday. I have asked the Sales manager for details. We did have a surveyor who came round to inspect the house and electrical distribution boards before the work was started. I will post details when these become available.

Growatt’s technical man Ben said the clamp installation looks OK. Here are 2 snaps. To the right of the meter LCD panel are 2 lights. The right-hand one sometimes shows red.

Great feedback @dnshorto - Thanks!

For the sake of others who will come across this Topic in future, let me explain that a “current clamp” measures the Amps flowing in the wire that it grips using electromagnetism, and without the need to actually connect to the conductor.

I’m pleased to see that the installer has been and rechecked the clamp. I’m less happy that it has been necessary to remove the outer layer of insulation from the live-feed to your Consumer Unit

If this is a temporary situation whilst they try to source a better current-clamp, then that’s fine. But there are really good reasons why the meter tails must be double-insulated! Let me just tag @PeterR1947 and see if he’d like to comment further.

As for your house having been granted G99 certification, that’s excellent. Your Solar Installer has done well for you!

You are unlikely to ever achieve the 9.66kW theoretical output from your solar panels because their efficiency drops slightly when they get hot. Depending on the manufacturer and the chemistry of the silicon technology, you are probably going to get between 90-95% of that rating in full/bright sunlight in summer.

Although we do have full sunshine during some cold days in winter, when the heating effect is reduced, the sun is lower in the sky, and thus it’s rays won’t be at right-angles to the panels.

Even so, the way in which your electrical control systems have been configured is equally important. It’s likely that the DNO has been satisfied that you won’t be exporting from all 28 panels and the 4 storage batteries simultaneously! There must be a fail-safe interlock within the software to prevent that.

The legend rEd stands for reverse Electricity detected; it was originally in the meter firmware to detect meter tampering.  Obviously, when solar panels are generating more than is required, electricity is flowing backwords through the meter, hence the rEd message.  It doesn’t indicate a fault and can be safely ignored,

This Forum is amazingly helpful and useful, clearly because of the well-informed and intelligent contributors! Thank you @PeterR1947 for pointing out the issues with reducing the cable insulation on the meter tails, and for translating rEd. Not “Red” at all, something the professional installers didn’t know. Thank you @Transparent for the alternative wiring  diagrams to show the two main methods of doing a grid-connection with PV Panels and Home Battery Storage, and for all your other shared wisdom. My own system uses two inverters, a Solis to convert the incoming solar DC to 230V AC, and a Growatt to charge the battery bank. Apparently the solar array was too large to use a hybrid inverter to perform both functions. Photos below.

On any reasonably sunny day, even a dull day with occasional sunshine all 4 batteries are showing a full charge which isn’t bad for November!

But the brilliant news is that my meter has finally been brought under control! Instead of the daily 9 to 10 kWh I have been seeing since 28th October the last 24 hours has registered 1 kWh. The Reverse Electricity Detected lamp has been on more or less continuously. All this searching for an answer has come down to the failure of the detection clamp to penetrate the double insulation of the meter tail. Nothing wrong with the set up after all, apart from this tiny fault. It’s just annoying that 20 days of say 9 units = 180 units at say 13p = £23 will have to be paid for electricity which the sun has been providing free of charge! I am very grateful to OVO for hosting this very helpful Forum which has facilitated the solution to my problem. Thank you.

Many thanks for the photos @dnshorto This helps us to pursue some of the loose ends with your particular arrangement.

1: Picking up what @PeterR1947  has just said, I can think of several reasons why a current clamp has been placed on the live meter “tail”. To help narrow this down, can you tell us what it connects back to? Is it the Growatt inverter?

2: Your first photo appears to show two bundles of 4mm² Solar Cable entering the house (garage?) via a hole now stopped up with white mastic. Are those the same six cables we can see entering the bottom left corner of the Solis inverter in the second photo?

And, incidentally, when I drill cable entry holes like this, I normally make it slope downhill to the outside so that any condensation runs out. I also line the hole with conduit and don’t allow anything to grip the cable. This permits heat to escape and for thermal-expansion in hot weather.

It may just be the angle of the camera, but it looks to me like your hole slopes the other way. If so, then you’re relying on the mastic to keep out rain, whilst any (thermal) movement of those cables will be pulling against it.

This point is a bit “picky” but, as I’m a self-builder, it’s the sort of detail which matters to me because I’m going to be living with the consequences of that hole for years to come!

3: To the right of the Growatt there are four enclosures on the wall. The bottom two appear to be both consumer units. What are the others, and are they part of the solar-install which has just been completed?

4: Earthing. I can see some hefty earth-wire connecting the four battery packs, which I assume then runs to the house’ central earth point (in a consumer unit?).

I would also expect to see some anti-surge units at the first point where the roof-top cables connect to an internal device. Is this device the Solis, or do the cables first go to a box which contains lightning protection, and possibly some isolating switches and fuses?

@PeterR1947 the readings were being taken daily from the original house meter. It is obviously from these readings that my electricity bill will be calculated, which is why I was concerned. The readings on the new solar-linked meters and phone app were all very positive (very low grid consumption), but those would be irrelevant to my power supplier. Thankfully, the re-positioning of the clamp closer to the conductor by removing a layer of insulation has stopped the meter when the solar or battery is supplying the power. From your helpful comments on the need for double insulation of the meter tail, and indication that a more sensitive clamp could be the answer, I intend that the present fix is only temporary.

 I will be keeping an eye on how the 4 Pylontech batteries perform on a day-to-day basis. Sunny days make a big difference, so November to March they may not get a full charge each day. For instance, by late evening yesterday they had dropped too low to provide domestic power so we began drawing from the grid, but that was an extra dull, gloomy day here in the North West. Given an hour or two of sun each day I predict they will provide most of our night-time needs.

Thanks Transparent. All sound stuff, as usual!

I will try moving the clamp to the position suggested.

The battery proximity issue is not likely to cause problems before next summer, but I can well see that a hot and sunny day might easily generate excess heat the way the batteries are stacked now. There is in fact lateral space on the shelf to form a void approximately 100mm wide between batteries 2 and 3, thus moving a little closer to the manufacturer’s recommendation. Scope too for heat-controlled forced air fan ventilation if needed. 

Much to learn!