'Off Grid' inverters and G99 certificates in UK

[SenileOldGit]

Hi, I am looking to replace my faulty MPP Solar PIP5048MKX inverters with either two Growatt SPF5000ES (which cannot export to the grid), or a Deye 8kW Hybrid Inverter (which can export to the grid, but this function can be turned off in the settings).
Do I need to apply for a G99 (or similar) form with my DNO if I buy either inverter(s)? Can I avoid this by buying the Growatts? I have no intention of ever exporting to the grid in the future.

 

[JCSchwarb]

Hi, I am looking to replace my faulty MPP Solar PIP5048MKX inverters with either two Growatt SPF5000ES (which cannot export to the grid), or a Deye 8kW Hybrid Inverter (which can export to the grid, but this function can be turned off in the settings).
Do I need to apply for a G99 (or similar) form with my DNO if I buy either inverter(s)? Can I avoid this by buying the Growatts? I have no intention of ever exporting to the grid in the future.

If I were senile, I would just forget about it! Sorry, mate, could t resist. I have no idea about the regs there or how to navigate them. Would anyone notice or care? I would think a hybrid is an overkill if you don’t intend to push energy back to grid. An offgrid inverter is essentially a UPS appliance, thus why would permission be required?

 

[SenileOldGit]

Look at this load of nonsense about 'DNOs':

Home - Cardinal Electrical

uk.smartenergy.co

It begins by saying:

"What is a DNO?


What does DNO stand for? Distribution Network Operator (DNO).



DNOs are licensed companies that carry electricity from the grid to your local area."


But then goes on to say:


"Why are there DNOs for solar panels?


Solar panel DNO’s are important because they allow you to access the SEG scheme."


Now they are presumably referring to an APPLICATION form, sent to a DNO, as a 'DNO'. Utterly ridiculous. The entire article presumes that you are going to be exporting power to the grid.


The third search result on Ecosia I found was this one:

Can I install over 4Kwp Solar without DNO approval | Premier Connections

Who are the DNO The DNO (distribution Network operator) the Grid. On a residential property you will most likely have a single phase 100amp supply coming into your property, on this basis the grid is responsible for how much power can be pushed back into the grid i.e. (Exported Power) from the...

www.premierconnections.co.uk

"Who are the DNO

The DNO (distribution Network operator) the Grid."


What does that even mean in English? Just read that entire article (if you can get through it) - astoundingly badly written, full of errors, and this is from a company hoping to get customers.


Anyway, back to my original post, has anybody else here applied for a G99 or similar? If you have an inverter that physically cannot export to the grid, do you need to inform your DNO?

 

[jamiegreen]

Surely if a proper transfer switch is fitted to prevent any accidental back feeding then I cant imagine any approval would be required, it would be no different to having a backup generator? But don't quote me on it, I have very little idea on applications etc with myself being completely off grid.

 

[JCSchwarb]

Look at this load of nonsense about 'DNOs':

Home - Cardinal Electrical

uk.smartenergy.co

It begins by saying:

"What is a DNO?


What does DNO stand for? Distribution Network Operator (DNO).



DNOs are licensed companies that carry electricity from the grid to your local area."


But then goes on to say:


"Why are there DNOs for solar panels?


Solar panel DNO’s are important because they allow you to access the SEG scheme."


Now they are presumably referring to an APPLICATION form, sent to a DNO, as a 'DNO'. Utterly ridiculous. The entire article presumes that you are going to be exporting power to the grid.


The third search result on Ecosia I found was this one:

Can I install over 4Kwp Solar without DNO approval | Premier Connections

Who are the DNO The DNO (distribution Network operator) the Grid. On a residential property you will most likely have a single phase 100amp supply coming into your property, on this basis the grid is responsible for how much power can be pushed back into the grid i.e. (Exported Power) from the...

www.premierconnections.co.uk

"Who are the DNO

The DNO (distribution Network operator) the Grid."


What does that even mean in English? Just read that entire article (if you can get through it) - astoundingly badly written, full of errors, and this is from a company hoping to get customers.


Anyway, back to my original post, has anybody else here applied for a G99 or similar? If you have an inverter that physically cannot export to the grid, do you need to inform your DNO?

Another good reason to not backfeed the grid

 

[SenileOldGit]

If I have a Deye 8Kw inverter installed and then apply for a G99 (or whatever form it is), will my chances of approval be higher because I don't want to export anything to the grid? Hasn't anybody in the UK here applied for a G99 form?

 

[jamiegreen]

This is really a dumb confusing process in the UK.. have a little read of this and see what goh think..

You cannot avoid getting DNO permission unless you are prepared to go off-grid, which is not advised. As the installed generation will be used to power grid-connected loads (with excess energy exported to the grid), the install needs to be compliant with grid regulations. DNO permission can only be avoided if the PV is to supply electricity to non-grid connected loads only, meaning these loads will only function when there is sufficient solar generation or with an off-grid battery system. Unfortunately dedicated off-grid PV and battery systems are incredibly expensive compared to a normal grid-connected system, further reducing the viability of this option.


What I get from that is as long as the system is not exporting to grid and is always kept seperate (by means of transfer switch or sperate outlets that are solely powered by the inverter/battery) then the loads would be considered off grid and application wouldn't be required?

Again.. just my guess and I'm not saying it's correct! I'd give the DNO a ring and see if you can get a straight answer.

 

[SenileOldGit]

jamiegreen, some inverters are incapable of exporting to the grid (like my current MPP Solar PIP5048MKX inverters), and the Growatt SPF5000ES, which I am thinking about buying to replace my faulty MPP Solar inverters. There are different definitions of 'off grid' - the MPP Solar 'off grid' range are connected to the grid, and can power loads and charge batteries with grid power, but they cannot export to the grid.
But I am amazed that nobody else on here from the UK has applied for a G99. When they have their electricity meter read, doesn't the meter reader notice the extra meter tails that are coming out of the meter and are going to your inverter (wherever it may be)?

 

[Mattb4]

This is really a dumb confusing process in the UK.. have a little read of this and see what goh think..

You cannot avoid getting DNO permission unless you are prepared to go off-grid, which is not advised. As the installed generation will be used to power grid-connected loads (with excess energy exported to the grid), the install needs to be compliant with grid regulations. DNO permission can only be avoided if the PV is to supply electricity to non-grid connected loads only, meaning these loads will only function when there is sufficient solar generation or with an off-grid battery system. Unfortunately dedicated off-grid PV and battery systems are incredibly expensive compared to a normal grid-connected system, further reducing the viability of this option.


What I get from that is as long as the system is not exporting to grid and is always kept seperate (by means of transfer switch or sperate outlets that are solely powered by the inverter/battery) then the loads would be considered off grid and application wouldn't be required?

Again.. just my guess and I'm not saying it's correct! I'd give the DNO a ring and see if you can get a straight answer.

Based on how I read that it says that using a transfer switch would not absolve you of needing DNO permission. It seems to say you would have to be without grid connection entirely. The use of a transfer switch still allows a grid connection to power loads and thus violates the

PV is to supply electricity to non-grid connected loads only, meaning these loads will only function when there is sufficient solar generation or with an off-grid battery system

BTW. grid tie inverters with zero export are likely going to need interconnect agreement and approval.

 

[Caesium]

But I am amazed that nobody else on here from the UK has applied for a G99. When they have their electricity meter read, doesn't the meter reader notice the extra meter tails that are coming out of the meter and are going to your inverter (wherever it may be)?

There are generally 4 tails into a single phase meter - two from the grid and two into your consumer unit (or sometimes an isolator first). Your inverter etc will be going to your consumer unit, not the meter. Which may not even be in the same place, for a long time meters were outside in white boxes. Meter readers don't even look twice at that sort of thing, they don't have the time to inspect your electrical system and they don't care. They probably have another 200 meters to read before the end of the day.

I can't remember the last time I had a meter reader come round actually! Must have been many years ago. Smart meters are making the position kinda redundant.

 

[jamiegreen]

Based on how I read that it says that using a transfer switch would not absolve you of needing DNO permission. It seems to say you would have to be without grid connection entirely. The use of a transfer switch still allows a grid connection to power loads and thus violates the


BTW. grid tie inverters with zero export are likely going to need interconnect agreement and approval.

The bit that throws me is the fact they also added in brackets "(with excess energy exported to grid)". So if we remove this feature, does this void the statement of not being able to power grid connected loads? Surely for it to be a "grid connected load" I would think they are referring to grid tie inverters that cover your household usage (whilst still being grid connected) and then export the excess.

But with a Transfer switch you are essentially disconnecting your house (or part of it) from the grid and thus your batteries and inverter would be running in an off grid situation.

jamiegreen, some inverters are incapable of exporting to the grid (like my current MPP Solar PIP5048MKX inverters), and the Growatt SPF5000ES, which I am thinking about buying to replace my faulty MPP Solar inverters. There are different definitions of 'off grid' - the MPP Solar 'off grid' range are connected to the grid, and can power loads and charge batteries with grid power, but they cannot export to the grid.
But I am amazed that nobody else on here from the UK has applied for a G99. When they have their electricity meter read, doesn't the meter reader notice the extra meter tails that are coming out of the meter and are going to your inverter (wherever it may be)?

Most people in the UK who haven't applied for the relevant applications will most likely be running a simpler system where they are powering their electronics separately via inverter only sockets or even extension leads that are totally separate from the grid mains. A transfer switch seems like a viable option but you'd technically need an electrician to fit this as the DNO fuse ideally want to be pulled for the meter tails to be wired into the transfer switch.

 

[SenileOldGit]

There are generally 4 tails into a single phase meter - two from the grid and two into your consumer unit (or sometimes an isolator first). Your inverter etc will be going to your consumer unit, not the meter. Which may not even be in the same place, for a long time meters were outside in white boxes. Meter readers don't even look twice at that sort of thing, they don't have the time to inspect your electrical system and they don't care. They probably have another 200 meters to read before the end of the day.

I can't remember the last time I had a meter reader come round actually! Must have been many years ago. Smart meters are making the position kinda redundant.

On my set up (all done by my electrician), he has two meter tails coming out of the meter, into a large switch (this can turn off the power going from the grid into my inverters), then two meter tails go from the inverter and into my consumer unit. It's very obvious that they are there, except I have two crates of 'stuff' (general junk that I dumped there) in front of the meter, on top of a kitchen type unit (my meter is in a porch), so you can't actually see what's below the meter itself.
But since I have a 12kW solar system, I expect my electricity bills (if I ever get a decent inverter that actually works) to be minute compared to what they used to be. Isn't the electricity company going to notice this? During the Summer I can't see how I would be using anything from the grid at all, I have 15kWh of batteries, and I imagine I'll easily be getting 30-50kWh per day, with a 12kW solar panel set up? I only use 10kWh per day normally.
So my grid goes into the two MPP Solar PIP5048MKX inverters, then comes back out from them and into my consumer unit. So I imagine that at some stage in the future, the electricity company will send a meter reader round, specifically to look at the meter, to see why I've not used any electricity for the past three or four months...

 

[JCSchwarb]

This is really a dumb confusing process in the UK.. have a little read of this and see what goh think..

You cannot avoid getting DNO permission unless you are prepared to go off-grid, which is not advised. As the installed generation will be used to power grid-connected loads (with excess energy exported to the grid), the install needs to be compliant with grid regulations. DNO permission can only be avoided if the PV is to supply electricity to non-grid connected loads only, meaning these loads will only function when there is sufficient solar generation or with an off-grid battery system. Unfortunately dedicated off-grid PV and battery systems are incredibly expensive compared to a normal grid-connected system, further reducing the viability of this option.


What I get from that is as long as the system is not exporting to grid and is always kept seperate (by means of transfer switch or sperate outlets that are solely powered by the inverter/battery) then the loads would be considered off grid and application wouldn't be required?

Again.. just my guess and I'm not saying it's correct! I'd give the DNO a ring and see if you can get a straight answer.

Going offgrid is not advised? By whom, lol.

Offgrid all in one units are effectively a large UPS. The grid tied inverters for selling power back are 2-3x more money, which can be used instead for batteries.

 

[FVScimitar]

Existing G99 in place but replacing solar inverter with hybrid

Hi, I've searched high and low but can't see the answer to this one... I already have G99 approval in place for 5kW export from 4.8kWp of panels and a Sofar KTLM-G3. All fine, but I recently decided to bite the bullet and get batteries, so I am about to purchase a Solis 5kW RHI 5G plus some...

diysolarforum.com

 

[gramos100]

Go off grid and stay off grid , all these regulations are aimed at controlling anyone who wants energy independence!

 

[JCSchwarb]

Go off grid and stay off grid , all these regulations are aimed at controlling anyone who wants energy independence!

Well said and very true!

 

[SenileOldGit]

This is really a dumb confusing process in the UK.. have a little read of this and see what goh think..

You cannot avoid getting DNO permission unless you are prepared to go off-grid, which is not advised. As the installed generation will be used to power grid-connected loads (with excess energy exported to the grid), the install needs to be compliant with grid regulations. DNO permission can only be avoided if the PV is to supply electricity to non-grid connected loads only, meaning these loads will only function when there is sufficient solar generation or with an off-grid battery system. Unfortunately dedicated off-grid PV and battery systems are incredibly expensive compared to a normal grid-connected system, further reducing the viability of this option.


What I get from that is as long as the system is not exporting to grid and is always kept seperate (by means of transfer switch or sperate outlets that are solely powered by the inverter/battery) then the loads would be considered off grid and application wouldn't be required?

Again.. just my guess and I'm not saying it's correct! I'd give the DNO a ring and see if you can get a straight answer.

Hi jamiegreen, where is that quote from?

 

[SenileOldGit]

Go off grid and stay off grid , all these regulations are aimed at controlling anyone who wants energy independence!

Well, my other option was to go completely off grid - but until I get a working inverter, I won't know how much power I'm actually generating each day. At the moment. MultiSIBControl is telling me that I get about 12kWh per day, but my inverters are faulty and I don't know if it's correct.
The other option is to simply buy the Deye 8kW inverter and get it installed by my electrician, don't bother to apply for a G99, and wait until something happens about it. The worst that can happen is presumably that the electricity company demand I get a G99, or that they threaten to cut off my supply - in that case, I'll just go off grid, and add some more solar panels if necessary. I use gas for heating my house so that won't be a problem. (And I have a multi-fuel stove, one and a half tons of coal, and a huge amount of firewood...)

Since apparently only one person here has applied for a G99, and I can find no information whatsoever about penalties for not doing so, I'm not going to worry about it. If I apply and they say no, then they know I have applied and may start demanding to see my inverter setup, and cut my electricity off. If I don't tell them, they will probably never know.

 

[Steve Fractals]

So what I did was:-

Got an AIO inverter that has a utility/AC-in for grid backup.
Moved all my house circuits off my main consumer panel onto a new panel that does not have a grid feed.
Installed a 40amp breaker cable from my main consumer unit to the inverter AC-in.
Installed cable from inverter AC-out to new loads panel AC-in feed.

With the above you do not need DNO approval as you are essentially off grid but with grid backup and absolutely no way to feed/export back to grid. I am using an MPP inverter as it has true power blending which means it can use my max solar output and then top up from grid where needed. Lots of AIO inverters can only do straight bypass to grid which means if not enough solar then they completely switch over to grid to power loads which is only useful if you also have a decent battery bank to charge. Also please note that if you do the same as me then you need to make sure you house loads don't exceed your inverter max output and if it does then only move circuits from main consumer that your inverter can handle e.g. maybe leave the electric cooker, shower or electric heating on the main consumer unit so they carry on with only being supplied by the grid due to the high power requirements.

 

[SenileOldGit]

Hi Steve Fractals, do you mean you are using an MPP Solar inverter? I think my electrician has wired up the consumer unit in the inverter box (the outside box I keep my inverters and batteries in) in the way you describe your set up. This may be why he has never mentioned DNO approval to me, I only found out about all of this after he had installed the inverters. I have two PIP5048MKX inverters that are each 5kW, so I have 10kW max output, and I have managed to overload the circuit breakers once, when I had a shower on, and two fan heaters, which went over the 10kW., but that's only once in four months.
The PIP5048MKX inverters cannot export to grid, but the Deye inverter I am thinking of replacing them with CAN export to grid, although this can be turned off in the settings, so how do I stand then, with the same consumer unit in my inverter box?