Solar export problem?

[S2D2]

57 minutes ago, Radian said:

It's a closer call than that though.  11p gas per kWh goes through a less than 100% conversion process when burnt in a boiler. It depends on the type of boiler and the flow temperature etc. To me it's almost as if they set the tariff accordingly.

Yes I haven't done the calcs just rounded up, it does seem to be a suspiciously linked rate - I guess they want to incentivise against gas offset otherwise they'd have less export to sell off and so less clout on the market. I guess the innocent explanation is just that gas and elec rates will always be linked at around these ratios. From an eco perspective I'd rather offset gas usage but will save the hassle for when rates drop.

[patp]

No gas here. We have Air Source Heat Pump. It is a new build so as efficient as we can make it.

Edited November 16, 2022 by patp

[Radian]

1 hour ago, patp said:

No gas here. We have Air Source Heat Pump. It is a new build so as efficient as we can make it.

 

Ah, this is where it gets a bit complicated. The ASHP will be timed to heat your HW but will also make up any shortfall with direct electric power into an immersion. That is possibly where your big consumption is coming from. The ideal would be to ensure HW heating coincides with PV availability to match this consumption, which may or may not have already been taken into consideration.

 

Furthermore, there is scope for ensuring that HW heating is more intelligent than relying on a timer alone. Unless there's an actual demand for HW, heating it can be delayed if there's going to be Solar PV a little later in the day - or even better, a Solar diverter is employed to make sure HW is only energised when an excess of Solar PV is available. The logistics are what makes this tricky, and the fact that I'm not aware of any commercial offerings that meet these needs.

[patp]

I will chat this through with the owner of the company that installed it. He is highly regarded in his field  Trouble is that he is also extremely busy in this current climate.

[patp]

Quick update. We are still battling this problem! The company we used has grown considerably and is involved in huge solar installations. They employed an office manager who was, apparently, useless and they are still picking up the pieces. One of those pieces is that she did not apply for our certificates (MCS is one and there was another) and so that has only just come through about nine months late. 

After much badgering from me they sent out their "solar expert" who was most puzzled that our export is roughly equal to our import! He went away and, eventually, came back with some sort of meter that he put on our smart meter (?). That was a week ago and we are still awaiting the results from the, week long, test he was supposed to be downloading. He tried to imply that we have air source heating and a fairly large square footage to heat. I told him that the heating was not on in summer (!) and that we never have it on at night now just during the day. We use the wood burner at night. All appliances are used when the sun is shining etc etc.  Cheeky burger mentioned using candles and, if it was cold, lighting them!

[SteamyTea]

26 minutes ago, patp said:

Cheeky burger mentioned using candles and, if it was cold, lighting them!

Was it me?

Kind of thing I say when I am being flippant.

[patp]

He is now going to "speak to the boss". Hmmmm.

[patp]

We have a result!

 

They are now saying that the inverter from the solar panels is "faulty". This in spite of two people saying it was "working fine".

Their solution is to replace it but, as that model is now discontinued, they will upgrade it to a larger one. Hmmm

Alongside this they will need to reconfigure some of the wiring on the roof.

They are also saying that the three phase supply is sending out "some" of our generated power straight to the grid so they will need to do some work on that.

 

The electrician who installed our set up told us that he is not trained in solar and has not installed three phase before. The boss is a highly skilled electrician and expert in all things solar and they now have a second solar expert in the company who was not there when we had our installation done. I am thinking that they left our chap to install it all in spite of him not being au fait with solar or three phase!

[joth]

 

Great to hear you are making progress at last on this!

 

 

45 minutes ago, patp said:

They are also saying that the three phase supply is sending out "some" of our generated power straight to the grid so they will need to do some work on that.

 

 

Interpreting this with a bit of license, they're saying that it's a 3 phase inverter, but your house is only consuming power from 1 (or 2) of the phases, so even if you turned everything in the house one, you'd never be able to self consume all the generated power as some goes on a phase you don't draw any loads on.

This is absolutely fine, so long as you have a v2 smart meter. (Do you? sorry can't see it in this thread but I though you had said), or a correctly configured dumb meter, it should balance out the phases (using net-metering across phases) so e.g. if PV generates 2kW on each of the 3phases,  but the house draws 5kW on a single phase, you shouldn't be billed anything for import but get paid 1kW for the net export (3x2kW - 5kW)

 

if they start fobbing you off saying your whole house needs rewiring to use 3phases push back 

 

 

45 minutes ago, patp said:

Alongside this they will need to reconfigure some of the wiring on the roof.

 

This probably means the new inverter requires a different number of strings, so they need to chain the panels a different way.

This should be fine.

 

Edited February 2, 2023 by joth

[SteamyTea]

Glad you have some acknowledgement that there is a problem.

Really does highlight the need for half decent energy monitoring. Especially if there is 3 Phase.

3 Phase is not really that useful in the domestic setting, except it does allow for a greater capacity.

Reducing the loads though time shifting i.e don't run a 6 kW water heater at the same time as charging the car and cooking supper, is probably an easier and much cheaper option.

[patp]

57 minutes ago, joth said:

 

Great to hear you are making progress at last on this!

 

 

 

Interpreting this with a bit of license, they're saying that it's a 3 phase inverter, but your house is only consuming power from 1 (or 2) of the phases, so even if you turned everything in the house one, you'd never be able to self consume all the generated power as some goes on a phase you don't draw any loads on.

This is absolutely fine, so long as you have a v2 smart meter. (Do you? sorry can't see it in this thread but I though you had said), or a correctly configured dumb meter, it should balance out the phases (using net-metering across phases) so e.g. if PV generates 2kW on each of the 3phases,  but the house draws 5kW on a single phase, you shouldn't be billed anything for import but get paid 1kW for the net export (3x2kW - 5kW)

 

if they start fobbing you off saying your whole house needs rewiring to use 3phases push back 

 

Thanks for this. This is a new build bungalow. They are the same company that installed the whole system. 

The three phase smart meter was installed in late December 2021 so should be up to date. The inverter is, apparently, "too small" so we assume that it is not a three phase one at all.

When we first called them out to investigate why we are getting such high bills they investigated and said that the import was the same as the export but denied it could be the installation causing it. They tried to say that we were using a lot of power! We are both elderly and retired and know how to keep our bills down! Our consumption compares equally with our usage in our old house that had no solar panels. We have over 40 panels on this new build.

We asked them, originally, to install 3 phase in order to future proof this new build bungalow for things like electric cars etc.

 

 

[patp]

1 hour ago, SteamyTea said:

Glad you have some acknowledgement that there is a problem.

Really does highlight the need for half decent energy monitoring. Especially if there is 3 Phase.

3 Phase is not really that useful in the domestic setting, except it does allow for a greater capacity.

Reducing the loads though time shifting i.e don't run a 6 kW water heater at the same time as charging the car and cooking supper, is probably an easier and much cheaper option.

We are extremely careful to spread the load of our appliances. Washing, tumble drying and dishwashing all wait for a sunny day and are turned on separately from each other. We have a wood burner but if we use the heat pump it is only on during daylight hours etc etc. 

So annoying to have to fight so hard to achieve the acknowledgment that things were not right. Such drastic action as to changer the inverter, re jig the solar strings and the three phase does smack of an almighty bloomer on their part.

[Dillsue]

2 hours ago, patp said:

So annoying to have to fight so hard to achieve the acknowledgment that things were not right. Such drastic action as to changer the inverter, re jig the solar strings and the three phase does smack of an almighty bloomer on their part.

Almost certainly a design/installation balls up!

 

2 hours ago, patp said:

We are extremely careful to spread the load of our appliances. Washing, tumble drying and dishwashing all wait for a sunny day and are turned on separately from each other. We have a wood burner but if we use the heat pump it is only on during daylight hours etc etc. 

 

Do you know how much youre generating at any particular time?? Without an accessible realtime indication its very difficult to schedule your usage. If you got 46 panels youve likely got quite a sizeable generation capacity and even in the winter may be generating enough to not have to worry to much about scheduling loads. Do you know what the kwp rating of the panels is?

[patp]

The panels can generate 14 kw at any one time. We were told that this is the limit allowed before having to apply for special permissions from UK Power Networks.

Since they went live in around April/May time we have generated over 9000 kwh. Our reason for getting agitated was that our usage, that we are being billed for, is about the same! The electricians kept telling us that our usage was normal but how could that be right if we have generated over 9000kwh?!

It now looks like the solar has all been going out and not feeding our usage

[SteamyTea]

1 minute ago, patp said:

The panels can generate 14 kw at any one time.

Panels can deliver more than the stated rating, it is only rated at one light level and one temperature, so is that p to 14 kW?

2 minutes ago, patp said:

limit allowed before having to apply for special permissions from UK Power Networks.

Was that limited by the inverter?

 

4 minutes ago, patp said:

Since they went live in around April/May time we have generated over 9000 kwh

Seems about the right generation, but if it is exporting on an unused phase, your imports will not be affected.

 

Obligatory kW and kWh.

[patp]

We were told that we had the maximum number of panels allowed by UK Power Networks for domestic systems.

 

The limit was managed by not having more panels. We had 42 panels but could have accommodated more. Any more would have caused us problems with UK Power Networks.

 

It seems that we have exported all of our generation. We have been billed for all of our usage with no allowance for having 40 odd solar panels in a very sunny region of the country!

[joth]

6 hours ago, SteamyTea said:

Seems about the right generation, but if it is exporting on an unused phase, your imports will not be affected.

 

*Sigh*

No, with a polyphase smart meter, it will net across phases so export on one will reduce the metered import on another phase.

 

 

Does the smart meter have a indoor display of real time usage? This would be the quickest way to confirm what's going on. If it doesn't, maybe it's not a smart meter at all.

Maybe share a photo of the meter.

 

 

[patp]

The smart meter is at the end of a long drive in the green box. It was a new, three phase, meter installed, by Octopus, earlier this year so must, surely, be a smart meter? As far as we can see there is only one reading on it and that is our usage.

They went and looked at it, scratched their heads, and then came back a few days later, with a device to fit to it so that could tell them what was going on. I presume that was a polyphase meter (?) They said that the export and import are almost exactly the same. The in house reading, that we can see, tells us, too, that we have imported roughly the same as we have exported.

Our usage roughly equals what we used in the old house before building this super insulated one and installing 40 odd solar panels!

 

I think that we can assume, therefore, that we are exporting all our solar generation. We are not signed up, yet, to any feed in tariffs due to another error on the electricians part where we did not get the MCS certificate until recently and it is still with Octopus awaiting their/UKPN approval.

 

The fact that they are going to install a new, larger, inverter and restring the solar panels together with some work on the three phase system says it all really. It is a complete turnaround from blaming us for using all the, generated power, and a whole lot more on top.

They made a big error, I believe, in leaving the original electrician, who admits to not being their solar guy or to know anything about three phase, to install our whole system which says it all really. 

[SteamyTea]

11 minutes ago, patp said:

The smart meter is at the end of a long drive in the green box. It was a new, three phase, meter installed

A picture of it may be useful, or any make and serial number.

 

There is probably a button or two that can be used to cycle though the readings.

Edited February 3, 2023 by SteamyTea

[Dillsue]

@patp A few pointers for you. UKPN are unlikely to be interested in how many panels or the panels output youve got. What they are interested in is what your inverter can export onto the grid and thats not necessarily the capacity of your panels. Without getting permission you can export 3.68kw per phase so with your 3 phase inverter youre limited to 11kw, unless you have permission to export more. If you already have an 11kw inverter and its being replaced with a bigger one, you need permission from UKPN. If youre not bothered about that its fine, but the concern could be that your questionable installation company maybe steaming ahead with something that is technically illegal. If thats what they are doing then you might want to consider their credentials. Maybe worth finding out what they're up to as ultimately its your responsibility.

[patp]

5 hours ago, Dillsue said:

@patp A few pointers for you. UKPN are unlikely to be interested in how many panels or the panels output youve got. What they are interested in is what your inverter can export onto the grid and thats not necessarily the capacity of your panels. Without getting permission you can export 3.68kw per phase so with your 3 phase inverter youre limited to 11kw, unless you have permission to export more. If you already have an 11kw inverter and its being replaced with a bigger one, you need permission from UKPN. If youre not bothered about that its fine, but the concern could be that your questionable installation company maybe steaming ahead with something that is technically illegal. If thats what they are doing then you might want to consider their credentials. Maybe worth finding out what they're up to as ultimately its your responsibility.

Thanks I will check when next I speak to the owner of the company. He is very knowledgeable, but also very elusive as he is always away on big contracts. I would imagine we don't have an 11kw inverter and that is why they are replacing it. He explained, right at the start, that if we went any larger than the 40 odd panels we would need to apply for permissions. We agreed that there was no need, on a three bedroom bungalow, to go any larger.

 

My reason for updating this post was to give feedback that we have solved the problem. Of course if their solution does not work then I will be back

[Dillsue]

2 hours ago, patp said:

Thanks I will check when next I speak to the owner of the company. He is very knowledgeable, but also very elusive as he is always away on big contracts. I would imagine we don't have an 11kw inverter and that is why they are replacing it. He explained, right at the start, that if we went any larger than the 40 odd panels we would need to apply for permissions. We agreed that there was no need, on a three bedroom bungalow, to go any larger.

The number of panels isn't really relevant, its the inverter capacity thats relevant. If its the installer thats telling you the number of panels is relevant then either they're not explaining things very well or they dont know what they are doing!!!

There'll likely be a data plate on the inverter so you may be able to see the inverter details

[patp]

It is me that is not explaining it very well. They work for large builders and local authorities, now, so are more than competent if not rather over stretched

The inverter was declared to be working fine by two people checking it and then, when the boss was brought in, he declared it "faulty". It is being replaced with a new, larger, one. This, of course, is cover up speech for "we installed one that was too small and now we have to fix it without losing face".

[Dillsue]

3 hours ago, patp said:

It is me that is not explaining it very well. They work for large builders and local authorities, now, so are more than competent if not rather over stretched

The inverter was declared to be working fine by two people checking it and then, when the boss was brought in, he declared it "faulty". It is being replaced with a new, larger, one. This, of course, is cover up speech for "we installed one that was too small and now we have to fix it without losing face".

Workiñg for builders and LA doesnt necessarily mean competance in a domestic scenario. There are limits to how much power you can push into the grid. On a construction site or LA site there maybe a consultant that deals with the DNO months or years before your installer gets to site so they never interface with the DNO or consider constraints. In your domestic install you are trusting them to ensure compliance, but you carry the can if they haven't done things correctly.

If you can't get the details off the inverter, its probably worth asking them if they have exceeded G98 limits and if they have, that a G99 is in place. If they are evasive or dont understand what you are asking, then you have your answer on their competance!!

[patp]

Well, we called out the owner or another solar installation company and he has found multiple faults on the system!

 

I have taken advice from another MCS Approved Installer, who inspected the installation, and gives me the following information :-

 

1)  There was not a MCS/RECC approved quote

      a) Shading issues were not noted - I believe this has led to an installation not fit for purpose as the tall trees in the immediate vicinity will cause heavy shading                issues.

       b) Annual yield was not noted therefore the customer has blindly accepted the quote.

2)  The installation has been installed wrong:

       a)  The panels on the south facing roof have been connected to form 1 x string. This potentially will create a voltage far higher than the inverter is designed to               take. This should have been connected to form 2 strings and therefore halving the voltage, and increasing the annual yield.

        b)  There is no RCD protection for the solar PV system.

        c)  I question whether the installer is qualified - the overall job would suggest otherwise!

3)     The MCS certificate has the wrong details.

           a) It has the wrong installation/commissioning date.

           b) It states only 1 system (should be 2 as the install covers two roof spaces.

4)     There was no handover pack issued - the client therefore has no warranties, guarantees or any information about the system.

 

I got a reply - 

 

1)  There was not a MCS/RECC approved quote

      a) Shading issues were not noted - I believe this has led to an installation not fit for purpose as the tall trees in the immediate vicinity will cause heavy shading issues.  Panels were installed where they are as you did not want to see them from the Garden.

 

       b) Annual yield was not noted therefore the customer has blindly accepted the quote.

 

2)  The installation has been installed wrong:

       a)  The panels on the south facing roof have been connected to form 1 x string. This potentially will create a voltage far higher than the inverter is designed to take. This should have been connected to form 2 strings and therefore halving the voltage, and increasing the annual yield. This I agree with an needs to be looked into & corrected if the case.

        b)  There is no RCD protection for the solar PV system. – Incorrect

        c)  I question whether the installer is qualified - the overall job would suggest otherwise!

 

3)     The MCS certificate has the wrong details.

           a) It has the wrong installation/commissioning date. I will look into this

           b) It states only 1 system (should be 2 as the install covers two roof spaces. Incorrect

 

4)     There was no handover pack issued - the client therefore has no warranties, guarantees or any information about the system. This is normally sent via email, I have requested the office put together a hard copy and post out to you asap or I can bring with me on Thursday.

I did not say that we did not want to see the panels from the garden! I commented that I thought all solar panels went on the South facing roof. If shading had been explained to me, and if I had got a proper estimate, as required under his registration, I would have happily had them on the West facing roof.

He came out to talk things through with us. He apologised for all the errors and offered to change the inverter from a Sonus to a Huawei free of charge, retrieve a whole load of strings that were hanging down behind the felting and, therefore not connected (!) and compensate us for our electricity costs and loss of FIT. He glossed over the shading issue from the mature trees on the South side saying we would generate enough for out usage even with the shade.

Our advisor came out again with his shade measuring camera and stood by his claim that the panels would not generate optimum power in the shade. He then looked for the RCD unit for the solar system and confirms that there is not one. We do have one large one for the main supply but not one for the solar. He still maintains that the paperwork is not correct. He tells us that the Sonus unit is the best one and cannot understand why they seem obsessed with changing it. My thinking is that they have a Huawei hanging around and hope fitting it for free will appease us.

My thinking is that I should go to the NICEIC and ask them to do an inspection and then take over the arbitration in the matter.

I feel drained