Pre-emptive upgrade to solar export allowance?

Reed_Richards

My solar PV system was installed in March 2019 and my inverter is limited to 3.68 kW of export although peak output from my panels is 4.8 kW. At the time the installer submitted a G83/2 form to this effect; I think this was the forerunner of G98. If I ever want or need to replace my current inverter I would opt for one that is not limited to 3.68 kW so I wonder if it would be wise to apply in advance for the G99 certificate that would let me do this, even though I have no plans to do so at present. But I'm not sure this is even possible; on the form I found you need to give details of the equipment you intend to use, which I can't do under the circumstances.

Netexporter

I had thoughts of doing my own G99 application, to see what export limit I could get, before getting quotes for expanding my system. However, if I have understood correctly, you have to state what inverter you intend to use, and other technical details, so I haven't pursued at any further.

NedS

G98 is an install and notify system, allowing inverters up to 3.68kW. You install the inverter and notify the DNO that you have done so. As the DNO will already have been notified that you have a 3.68kW inverter, you can replace it at any time with a new inverter up to 3.68kW.

G99 is the application process for inverters above 3.68kW. You must apply and receive permission before connecting to the grid, and then once permission has been granted you must notify the DNO that you have connected the permitted equipment. There is a time limit between the offer to connect and connection happening, usually 90 days, before the offer to connect expires. You must connect and notify the DNO that you have done so within the time period otherwise the permission to connect expires. So you cannot just make a speculative application and sit on it until your current inverter dies.

This is because the DNO needs to know what is connected to the grid at any one time, and if you are not going to use that capacity then it can be assigned to someone else on a first come first served basis.

NedS

https://forums.moneysavingexpert.com/discussion/comment/81933851#Comment_81933851

One way to do that, would be to apply for a Powerwall 3 which includes an 11kW inverter, but can be downrated in 1kW steps in software on commissioning, so can be 3.68kW, 5, 6, 7, 8, 9, 10 or 11kW depending what the DNO approves. The site export limit can also be independently set of inverter rating, so you could have an 11kW inverter rating with a 5kW export limit if that's what the DNO will allow.

Once you have an application in, you can then talk to the DNO about what they may be able to approve and the limitations and concerns they are working with. I found my local NG person very responsive and helpful.

Netexporter

I've already got some Fogstar batteries. I want a Sunsynk 8kW hybrid inverter. I think you can downrate the grid export on that model, if necessary, but I want the full beans to run the house when I'm in off-grid mode. As I don't know what ready made gateways, or bespoke set-up that can be installed, I've decided to leave it to the installer.

Qyburn

The G.99 approval consists of an initial "offer" from the DNO, which you need to accept prior to commissioning. The details may be DNO specific but SSEN say you need to install and commission with three months. It's not clear if that's three months from offer, or from acceptance.

Reed_Richards

Thank you for the advice. It's precisely because I don't want the DNO to assign their total export capacity away to others that I wanted to make a pre-emptive bid for some. Sadly I learn that that isn't possible; in fact the boot is so far on the other foot that you have to specify what equipment you are going to use before knowing if you will be allowed to use it.

NedS

https://forums.moneysavingexpert.com/discussion/comment/81934927#Comment_81934927

My understanding is that when you make a G99 application, you would initially apply for what you want (aim high), and if the DNO are unable to grant permission, they will come back with an offer of what they can allow or a quote to upgrade the network to get you to where you want to be.

It is the start of a dialogue. For example, you may want a 10kW inverter. If the inverter has an approved mechanism for limiting export, they may allow you a 10kW inverter with export limited to 5kW. If the inverter does not have an approved mechanism to limit export, they may reject the 10kW inverter/export, and advise they may be able to allow 5kW. You may go back and say there is a 6kW model in the range, would they allow that? If they stick to 5kW, you may need to look at other brands of inverter that offer a 5kW if your chosen brand only offers 3.68kW and 6kW models, for example.

When we did our G99 application, I found the DNO officer very helpful. He was quite happy to spend 45mins on the phone with me discussing what we wanted to achieve, explaining the limitations of my connection and their offer (which wasn't initially clear to me), and what my options were. They want to be able to say yes and approve adding green tech to the grid, but obviously have to work within the safety parameters to keep the grid stable and safe for everyone. Our initial application was refused and we were then invited to submit a second fast tracked application that he approved almost immediately, having discussed and agreed it informally. We didn't get everything we wanted by a long shot, but they worked with us to find a solution that was at least viable and worked for us.

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/81935202#Comment_81935202

The level of customer service you have described is an ideal scenario these days I'm afraid. As an example, UKPN have a total of 6 full time staff to cover all of the South East of England's DNO applications. This was manageable till March 5th 2026, when volume increased exponentially. Said another way, these days it appears to be less of a dialogue and more of a diktat. Sadly, this has meant that several DNO approvals are taking weeks, not days.