Growatt Inverter wired wrongly?- solar meter giving wrong readings.

[user 36170]

Hi,

I am a consumer rather than an electrician. I hope that is ok!

I had a Growatt SPH3600 Hybrid Inverter installed last October along with 3 x 3.3kW Growatt batteries, and they are working fine except that for some reason all the power that goes both to and from the batteries passes through my solar meter, along with the solar generation. This meant that when I read my meter for my FiT payment at the end of December it was reading about 900kWh rather than the approximately 120kWh my solar panels had actually generated. Not surprisingly Octopus didn't believe the numbers!
I've been in touch with my installer and his only response so far is "I am looking into it - it's not a simple solution".
Does anyone on here know what he might have done wrong, so that I can pass on any useful information to him?
Thanks in advance.

 

[Si_Oakwood]

Hi Ben,

I'm also a consumer and newbie but I have a similar setup to you, i.e. SPH3600 and 2 growatt batteries (installed last Aug) so thought I'd chip in. My installer fitted a solar meter (an emlite eca2.nz) but he didn't know what it was (he was just told to install it). The meter turned out to be useless as they are FiT meters and the FiT payment scheme was closed.

So, are they actually FiT payments you're talking about, or SEG payments which replaced them several years ago? And do you have a smart meter for your elec?

My understanding (and I may be wrong) is that solar (aka FiT) meters measure total solar production regardless of how the elec is used which was fine for the old FiT scheme. But SEG payments work differently and you need the exported amount which my supplier (British Gas) told me was only possible with a smart meter. I also asked on here if the FiT meter could be wired differently to give export figures and was told no (see here).

If Octopus are more flexible and do allow you to manually submit your export figures without a smart meter I'd be interested in that too.

Hope that helps
Si

 

[binky]

interesting, if you are using cheap off peak leccy to charge up the batteries overnight, then any energy imported and subsequently released will far exceed the solar generation. If you are just charging the batteries from the solar panels, then you should only see what has been generated, bar losses within the charging system. Trouble with a hybird, if you are charging from grid , then a simple generation meter (simple single phase unit) is never going to differentiate between energy from solar and energy from charging the batteries on off-peak. There is a simple solution, install another simple meter inline with the generation meter to record imported energy from the grid, and subtract that from what the generation meter is reading.

 

[user 36170]

Hi Ben,

I'm also a consumer and newbie but I have a similar setup to you, i.e. SPH3600 and 2 growatt batteries (installed last Aug) so thought I'd chip in. My installer fitted a solar meter (an emlite eca2.nz) but he didn't know what it was (he was just told to install it). The meter turned out to be useless as they are FiT meters and the FiT payment scheme was closed.

So, are they actually FiT payments you're talking about, or SEG payments which replaced them several years ago? And do you have a smart meter for your elec?

My understanding (and I may be wrong) is that solar (aka FiT) meters measure total solar production regardless of how the elec is used which was fine for the old FiT scheme. But SEG payments work differently and you need the exported amount which my supplier (British Gas) told me was only possible with a smart meter. I also asked on here if the FiT meter could be wired differently to give export figures and was told no (see here).

If Octopus are more flexible and do allow you to manually submit your export figures without a smart meter I'd be interested in that too.

Hope that helps
Si

Hi Si,

I'm definitely still getting FiT payments from the government (paid by Octopus) for my solar generation (I've had panels since 2016). Octopus pay me for what I send them back to the grid (both solar generated and stored in my batteries and sent back) through my smart meter, on Agile Outgoing Octopus rates, so varying through the day, and then give me a FiT payment at the end of every quarter (only about 5p per kWh I think) but it all adds up in the spring and summer, so worth hanging on to.

The solar meter is SUPPOSED to just record what I generate, but seems to now record everything going to and from the battery instead. Someone on another forum suggested it might be something to do with "the monitoring CT’s (toroidal current transformers ) wrongly configured." I've passed this on to my installer (who is unfortunately not local), but he seems to be ignoring me now, so I assume it wasn't helpful. I asked a local installer who said who was not allowed to help me as my system was the responsibility of the installer for the first two years.

Ben

 

[user 36170]

interesting, if you are using cheap off peak leccy to charge up the batteries overnight, then any energy imported and subsequently released will far exceed the solar generation. If you are just charging the batteries from the solar panels, then you should only see what has been generated, bar losses within the charging system. Trouble with a hybird, if you are charging from grid , then a simple generation meter (simple single phase unit) is never going to differentiate between energy from solar and energy from charging the batteries on off-peak. There is a simple solution, install another simple meter inline with the generation meter to record imported energy from the grid, and subtract that from what the generation meter is reading.

Hi Binky,
Yes, I am charging on cheap Octopus Agile overnight, and yes that does far exceed the solar generation. and it goes back through the meter when the battery discharges as well I think! Who could install a second meter? Wouldn't it make sense to make it a second solar meter feeding in to the existing one, to save the maths? Would that be for Octopus to do? I don't really understand why the solar meter needs to be inside the loop - let it pretend it is on the roof with the panels and make all the connections downstairs. But I am by no means an expert!

 

[ProDave]

Try posting a picture of exactly how the meter is connected in relation to the inverter.

Did you replace your original inverter that you had when you started the FIT with the hybrid?

 

[binky]

Hi Binky,
Yes, I am charging on cheap Octopus Agile overnight, and yes that does far exceed the solar generation. and it goes back through the meter when the battery discharges as well I think! Who could install a second meter? Wouldn't it make sense to make it a second solar meter feeding in to the existing one, to save the maths? Would that be for Octopus to do? I don't really understand why the solar meter needs to be inside the loop - let it pretend it is on the roof with the panels and make all the connections downstairs. But I am by no means an expert!

any electrician could install a second meter, or better still, they should have installed a meter with import/ export capabilities - not exactly sure how one of those would work as I've never done it, but it would read imported leccy and exported again, so you should be able to calculate the difference. I'm a little surprised Ocotpuss havn't installed some form of smartmeter as seems to be their want.

 

[user 36170]

any electrician could install a second meter, or better still, they should have installed a meter with import/ export capabilities - not exactly sure how one of those would work as I've never done it, but it would read imported leccy and exported again, so you should be able to calculate the difference. I'm a little surprised Ocotpuss havn't installed some form of smartmeter as seems to be their want.

I have a smart meter from Octopus, and it is working fine - recording imported and exported power just as expected. It is just the solar meter that is showing wild figures - 900kWh in Q4 last year, while the Growatt dashboard indicated I'd actually had around 116kWh of solar from 20th October up to the end of December (and I didn't read the solar meter when the inverter was installed (as I wasn't expecting anything like this to happen), so I don't know how much during the first few weeks of October). Octopus want the figures from the meter (understandably since they are getting the money from the government for FiT), so I suspect your initial suggestion of a second regular meter and then doing some maths wouldn't satisfy them either.

I tried to get some advice from a local installer, but he said it was all the responsibility of my installer for the first two years after installation, so he wouldn't touch it. And my installer is not responding to me at the moment, and is not local.

 

[Murdoch]

Could you post photos showing the meters ?

 

[user 36170]

Could you post photos showing the meters ?

I will when I get home from work.

 

[user 36170]

Try posting a picture of exactly how the meter is connected in relation to the inverter.

Did you replace your original inverter that you had when you started the FIT with the hybrid?

I'll post a pic when I get home from work.

Yes, the new hybrid inverter replaced the one installed with the solar panels in 2016.

 

[ProDave]

I'll post a pic when I get home from work.

Yes, the new hybrid inverter replaced the one installed with the solar panels in 2016.

You might be on thin ice with the FIT. Making substantial changes to the installation might invalidate or change the FIT contract.

I would have chosen an ac coupled battery system leaving the original inverter and it's metering untouched.

 

[user 36170]

You might be on thin ice with the FIT. Making substantial changes to the installation might invalidate or change the FIT contract.

I would have chosen an ac coupled battery system leaving the original inverter and it's metering untouched.

If that is the case then I'll take it on the chin and move on. Octopus don't seem to be telling me that is the case, and they know all about it. They just aren't very helpful in suggesting a solution. I went with what my installer advised.

 

[binky]

I'll post a pic when I get home from work.

Yes, the new hybrid inverter replaced the one installed with the solar panels in 2016.

You don't want to be losing that FiT rate, easy answer, separate hybrid inverter and batteries from the solar array, buy a cheap inverter for the solar panels ( or refit the original if you still have it).

Getting sense from FiT providers is like herding cats, you are better off sorting the issue yourself, although, to be frank the battery installer shouldn't have buggered it up in the first place.

 

[user 36170]

I will when I get home from work.

Not sure pics will help. The meter is in the meter box, and the inverter is underneath the meter box and you can't really follow where the cables go. But here you go - a pic of the meter, one of the bottom of the inverter where the cables are connected, and the two cutout switches - one for the inverter and one for the solar.

 

[user 36170]

You don't want to be losing that FiT rate, easy answer, separate hybrid inverter and batteries from the solar array, buy a cheap inverter for the solar panels ( or refit the original if you still have it).

Getting sense from FiT providers is like herding cats, you are better off sorting the issue yourself, although, to be frank the battery installer shouldn't have buggered it up in the first place.

It was his first time installing Growatt I think - we had initially intended Givenergy, and given that Growatt don't yet have any software to link them to Octopus tariffs I wish I'd waited till Givenergy had been available. Setting the charge and discharge times every day is a pain in the bum.

He took the original inverter away with him (at my request as I didn't have any use for it) and to be honest I don't really have room for two inverters. The FiT is only paying me just over 5p/kWh. I think I got about £60 for the summer months last year and a bit less for spring. I suspect I was only due about a tenner at Christmas. Nice to have, but not the end of the world if I lose out on it.

 

[binky]

It was his first time installing Growatt I think - we had initially intended Givenergy, and given that Growatt don't yet have any software to link them to Octopus tariffs I wish I'd waited till Givenergy had been available. Setting the charge and discharge times every day is a pain in the bum.

He took the original inverter away with him (at my request as I didn't have any use for it) and to be honest I don't really have room for two inverters. The FiT is only paying me just over 5p/kWh. I think I got about £60 for the summer months last year and a bit less for spring. I suspect I was only due about a tenner at Christmas. Nice to have, but not the end of the world if I lose out on it.

Wouldn't make any difference which hybrid inverter was installed, it's a metering issue.

4p fit, meh, not worth worrying about much, but would pay for an inverter eventually. Ask the installer if they still have it.

 

[ProDave]

Right, if I am understanding this, a simple inverter then a meter then connection to the CU and hence grid. The meter measures whatever the inverter generates and that is what you get paid for.

Your installer has ripped out the original simple inverter and replaced it with a hybrid inverter and batteries probably still connected via the same meter to the same connection in the CU.

Now the meter will measure anything that the inverter produces, whether that has come from the solar PV or from the hybrid inverter importing power at the cheap rate and then re exporting the same power at a more expensive rate.

No wonder the "generation" meter is reading a lot more. It is no longer performing the function of a "generation" meter.

Your choice is put it back exactly as it was, grovel, and try and retain your FIT contract.

Or abandon the FIT contract, tell them you have made changes that invalidate it and terminate it.

Sorry but you should have sought advice before doing this. It is a shame your installer did not understand it.

 

[user 36170]

Wouldn't make any difference which hybrid inverter was installed, it's a metering issue.

4p fit, meh, not worth worrying about much, but would pay for an inverter eventually. Ask the installer if they still have it.

I'm not sure there's anything to be gained from a second inverter. My smart meter is measuring my import and export fine. If I have to write off the FiT payments that's what I'll do.

 

[user 36170]

Right, if I am understanding this, a simple inverter then a meter then connection to the CU and hence grid. The meter measures whatever the inverter generates and that is what you get paid for.

Your installer has ripped out the original simple inverter and replaced it with a hybrid inverter and batteries probably still connected via the same meter to the same connection in the CU.

Now the meter will measure anything that the inverter produces, whether that has come from the solar PV or from the hybrid inverter importing power at the cheap rate and then re exporting the same power at a more expensive rate.

No wonder the "generation" meter is reading a lot more. It is no longer performing the function of a "generation" meter.

Your choice is put it back exactly as it was, grovel, and try and retain your FIT contract.

Or abandon the FIT contract, tell them you have made changes that invalidate it and terminate it.

Sorry but you should have sought advice before doing this. It is a shame your installer did not understand it.

My FiT contract is only worth around 5p/kWh, so it doesn't come close to competing with what I can make by storing Octopus's power at night and selling it back to them in the afternoon!

I was trusting my installer to advise me. He certainly seemed fairly knowledgable - although as it turned out not about Growatt.

I'll get back in touch with Octopus next week and tell them I think I've invalidated my FiT contract and see what they say. To be honest when I switched to Agile Outgoing last summer (before batteries/inverter) I was expecting to lose the government bit anyway, and then they requested a reading in September and paid me money!