Green Building Forum - solar PV DNO export limit.

solar PV DNO export limit.

gustyturbine — Sun, 06 Aug 2023 12:03:35 +0100

Hi all, I had hoped to fit up to 10kW PV on my new build. Unfortunately, as many experience I'm limited to 3.68kW export due to grid restriction. So, should I still consider a larger system that limits export? I am looking at a heat pump so that will be energy hungry. I'm also now considering SIPS in an attempt to reduce my energy demand. This house will also have MVHR and 3g. I drive an EV. I'm not experienced with small, domestic battery storage yet. I was also looking at possibly using second hand PV panels from repowered utility sites. My array will be ground mounted. I was thinking that if I'm limited to 3.68kw export should I forget MCS and self install and save money? Thoughts appreciated. Thanks.

solar PV DNO export limit.

revor — Sun, 06 Aug 2023 12:26:28 +0100

Think you need MCS to connect to grid regardless of your intention or not to export. You could try asking how much you can export as things do change. Last year I queried how much it would cost to export more than the Â£3.68 kW and was pleasantly surprised to be told could go to 5kW. It would cost Â£750 for a test to see if I could export more than that but seeing as have only 6kW of generation would not be worth it. At moment the export value is not good last month got ave of 9.5p per kwh so it is better for us to have it in the battery and use it. Last 3 months have used very little grid supply 99% of use from solar and battery. As you have an EV you should be able to use a good chunk of your generation depending on size of your vehicle battery. If you go down route of SH panels make sure they are MCS certified it is possible but do not know for certain if the commercial ones are so covered. As you are a new build is there a possibility of you getting 3 phase on site then you can export 3.68kW per phase? If it is a big build you may need that for a heat pump.

solar PV DNO export limit.

djh — Sun, 06 Aug 2023 16:29:24 +0100

Posted By: revorThink you need MCS to connect to grid

Are you sure about that? I know you need them if you plan to get paid for export (or generation historically).

Posted By: gustyturbineshould I still consider a larger system that limits export?

That depends on what your goal is. You'll need to be able to curtail the panel's output, but you should get a higher average generation. Whether you can use the turbine in conjunction with your car depends on how you use the car - only you can work that out.

solar PV DNO export limit.

philedge — Sun, 06 Aug 2023 16:58:59 +0100

No need for MCS to connect to the grid, just need a type approved inverter listed on the ENA database. Most suppliers want you to have an accreditted MCS system for them to pay for your export, but that may not always be the case:)

Have you asked if you can have more export than 3.68kw? Even if you are limited to 3.68kw thats quite a bit of power to have if it runs for much of the time if you had a large array with export limitation. Some inverters allow significant oversizing of the array. Solaredges SE3680H is rated at 3.68kw but can have up to 5.6kw of DC input so it will run at its 3.68kw limit for much longer than it would if it had 3.68kw of panels connected and stay within DNO G98 limits

Have a good think about using older ex solar farm panels as mounts can rack up quite a cost and if fitting older less efficient panels you might need significantly more mounting kit than if you were using newer more efficient and more powerful panels. If you are going for ground mount be aware that planning permission is needed for more than 9m2 of panels although if you are out of sight its not likely anyone is going to complain

solar PV DNO export limit.

revor — Mon, 07 Aug 2023 10:26:09 +0100

Posted By: djhAre you sure about that? I know you need them if you plan to get paid for export (or generation historically).

What I stated was what I think and is based on what I had to do. You do need MCS for export as stated but perhaps I should have been more specific in that you need the Manufacturers declaration of conformity according to G100 "technical Requirements for Customer Export Limiting schemes. This detailed document covers how the export whether set to Zero or the maximum allowed is controlled. This has to be set by the installer and locked off so owner cannot interfere with it. It has to be displayed in the location of the inverter. My inverter export is software controlled i.e. it is controlled by a meter rather than a clamp. If set for zero export then what happens the inverter controls the solar input so if not being used it it ramps down. Other inverters will work differently I guess. If you are in this situation one needs to work out if cost getting the MCS as an extra can be justified by what you can expect to earn. In my case it was touch and go so I paid an installer Â£430 for this and for doing the DNO application. After the high wholesale prices last year I have already arrived at the break even point so has been worth it Regardless of whether you intend to export or not the application to the DNO for the connection of the inverter has to be done, as it will be connected to the grid as it will need power to operate. The other thing one can do and what a neighbour has done is a DIY system which is not connected to the grid but has inverter charge controller and batteries. What he does is when he has enough power from solar or batteries he has a changeover switch that isolates the grid and brings on the solar. When my application went in to the DNO I had to supply the details of the approval of the solar panels as well even though at that point I had not intended to go for the MCS.

Posted By: philedgeif you are out of sight its not likely anyone is going to complain

Famous last words comes to mind

solar PV DNO export limit.

djh — Mon, 07 Aug 2023 11:39:57 +0100

Posted By: revorWhat he does is when he has enough power from solar or batteries he has a changeover switch that isolates the grid and brings on the solar.

How does he avoid it resetting all the clocks and rebooting all the computers etc? That's what always puts me off such schemes.

solar PV DNO export limit.

revor — Mon, 07 Aug 2023 12:43:15 +0100

Posted By: djhHow does he avoid it resetting all the clocks and rebooting all the computers etc? That's what always puts me off such schemes.

He is not bothered with those sort of trivialities lives on his own bit of a chancer with things, likes experimenting gets it wrong starts again sort of chap. Does only little research, dives into things, offered him books and information that may help but declines.

solar PV DNO export limit.

RobL — Mon, 07 Aug 2023 13:07:20 +0100

I think a hybrid inverter makes for a more reliable, simpler to operate, system. Generally they can be setup to load match - so your import is zero if it's been sunny enough over the last day or two, but it will import if needed. Also, if you turn on oven+toaster+kettle+++, all is ok; with a changeover switch I very much doubt it would be ok.
There are lots to choose from: Givenergy and Sunsynk are quite popular, there are many others. Eg you could install a 3.6kW ECCO Sunsynk hybrid system with up to 7kW** of PV, and lots of batteries (Pylontech are popular, others are available). **I think you'd have to be both charging the batteries and exporting to make use of the 7kW.
To do this you'd need as a minimum an electrician to make the connection to your consumer unit, and to inform your DNO about the system. Technically you can export if you did this; maybe you'll get paid to export even, as Octopus seem to be moving away from MCS as a requirement for this:
https://www.thetrailblazer.co.uk/blog/octopus-energy-takes-step-away-from-mcs#:~:text=Energy%20company%20Octopus%20Energy%2C%20whose,accredited%20installers%20for%20their%20solar.
Of course, the simpler option is to find an mcs registered company, and get the whole hybrid system installed by them.

solar PV DNO export limit.

revor — Mon, 07 Aug 2023 15:34:34 +0100

Posted By: RobLseem to be moving away from MCS as a requirement for this:
https://www.thetrailblazer.co.uk/blog/octopus-energy-takes-step-away-from-mcs#:~:text=Energy%20company%20Octopus%20Energy%2C%20whose,accredited%20installers%20for%20their%20solar." rel="nofollow" >https://www.thetrailblazer.co.uk/blog/octopus-energy-takes-step-away-from-mcs#:~:text=Energy%20company%20Octopus%20Energy%2C%20whose,accredited%20installers%20for%20their%20solar.

The MCS won't like this they have been losing members and income. One installer told me that they will accept almost anyone to get their numbers up.

solar PV DNO export limit.

revor — Mon, 07 Aug 2023 17:18:44 +0100

As we are on the topic of solar install came across this a couple of days ago.
https://www.youtube.com/watch?v=OmHtcfWUI4w

solar PV DNO export limit.

borpin — Mon, 07 Aug 2023 22:24:17 +0100

The GiveEnergy All-in-One is getting some good press. It includes the UPS function AIUI, but not a divert (again AIUI) so not quite 'All in One'.

solar PV DNO export limit.

revor — Tue, 08 Aug 2023 20:19:28 +0100

Posted By: borpinThe GiveEnergy All-in-One is getting some good press. It includes the UPS function AIUI, but not a divert (again AIUI) so not quite 'All in One'.

Seems a good spec good price including a gateway for less than Â£7K. Looks like it would make an ideal addition to a current solar PV system Would like to know how it would interface with a hybrid charger and existing battery. Setup in the instructions shows a standard inverter. V heavy at 173kg

solar PV DNO export limit.

djh — Tue, 08 Aug 2023 20:40:48 +0100

Posted By: borpinIt includes the UPS function AIUI

It seems to include switchover on power fail, with a short interruption of one mains cycle, but not UPS standard as of yet. :(

solar PV DNO export limit.

gustyturbine — Thu, 10 Aug 2023 09:40:45 +0100

Thank you all. Very interesting. I would need planning permission for sure as my neighbours are NIMBY's. I will look at the GiveEnergy systems and see how they look.
I'm also now looking at changing from conventional build to SIPS to reduce energy demand.
The DNO have confirmed the 3.68kW export limit due to grid constraints and three phase is too costly.

solar PV DNO export limit.

borpin — Fri, 11 Aug 2023 08:07:18 +0100

Posted By: gustyturbineI would need planning permission for sure as my neighbours are NIMBY's.

Only is outside of PD. They can NIMBY all they want, but if it is PD, tough!

solar PV DNO export limit.

philedge — Fri, 11 Aug 2023 23:22:24 +0100

Posted By: borpin
Posted By: gustyturbineI would need planning permission for sure as my neighbours are NIMBY's.
Only is outside of PD. They can NIMBY all they want, but if it is PD, tough!

10kW of panels is way more than 9m2 PD limit

solar PV DNO export limit.

Dougmlancs — Sat, 12 Aug 2023 06:16:47 +0100

Isnâ€™t the 9m2 limit just for ground mounted?

solar PV DNO export limit.

revor — Sat, 12 Aug 2023 07:42:55 +0100

It's always best to check you do not want to fall foul of planning particularly as you are also doing a new build. Once they suspect you are not complying with the rules they will be all over you like a rash.

solar PV DNO export limit.

philedge — Sat, 12 Aug 2023 14:01:09 +0100

Posted By: DougmlancsIsnâ€™t the 9m2 limit just for ground mounted?

I beleive so. OPs array is ground mounted

solar PV DNO export limit.

borpin — Sat, 12 Aug 2023 20:10:57 +0100

Point is, you don't get Planning Permission because of NIMBYs, you get it because you have to!

solar PV DNO export limit.

gustyturbine — Mon, 14 Aug 2023 13:21:33 +0100

Agreed, however ground mounted isn't PD anyway so planning required unfortunately along with all of the other costs involved.

solar PV DNO export limit.

revor — Sat, 19 Aug 2023 11:25:38 +0100

You save on scaffold and you can DIY it. This the array I built with my wife

solar PV DNO export limit.

revor — Sat, 19 Aug 2023 11:28:40 +0100

The finished job

solar PV DNO export limit.

borpin — Mon, 21 Aug 2023 07:07:19 +0100

Posted By: revorYou save on scaffold and you can DIY it.

That looks interesting. Did you write up how you did it anywhere? I have a patch of land and I have been mulling putting something like this on it.

solar PV DNO export limit.

tony — Mon, 21 Aug 2023 08:22:48 +0100

Did you get planning permission?

solar PV DNO export limit.

revor — Mon, 21 Aug 2023 09:51:12 +0100

Posted By: borpinThat looks interesting. Did you write up how you did it anywhere? I have a patch of land and I have been mulling putting something like this on it.

No not written it up but pretty straight forward. The top soil was removed and used elsewhere in our growing area we had a contractor here when doing our build and he excavated the soil. We had rescued a lot of broken bricks concrete etc which we had crushed on site and recycled into our roadways and for under the solar panels. The hollow concrete blocks placed on top and rebar length hammered in at an angle, filled in with concrete and bedded and haunched in. Then levelled off to top of blocks with more hard core topped with finer stuff. The frame is by Renusol (https://www.renusol.com/en/) gave them the size of panels location and they calculated exactly what I needed as bills of material. Compressive install instructions right down to the torque settings of the fixings. The frame anchored to the blocks via Hilti SS anchors. May seem overkill but we are in an exposed area and I tend to be a belt and braces chap.

Posted By: tonyDid you get planning permission?

Yes Was pretty straight forward but was called in to committee by a local councillor but her objection was thrown out in minutes after positive support for the application by others and she then withdrew her objection.

solar PV DNO export limit.

gustyturbine — Mon, 04 Sep 2023 15:12:48 +0100

Posted By: revor
Posted By: borpinThat looks interesting. Did you write up how you did it anywhere? I have a patch of land and I have been mulling putting something like this on it.

No not written it up but pretty straight forward. The top soil was removed and used elsewhere in our growing area we had a contractor here when doing our build and he excavated the soil. We had rescued a lot of broken bricks concrete etc which we had crushed on site and recycled into our roadways and for under the solar panels. The hollow concrete blocks placed on top and rebar length hammered in at an angle, filled in with concrete and bedded and haunched in. Then levelled off to top of blocks with more hard core topped with finer stuff. The frame is by Renusol (https://www.renusol.com/en/) gave them the size of panels location and they calculated exactly what I needed as bills of material. Compressive install instructions right down to the torque settings of the fixings. The frame anchored to the blocks via Hilti SS anchors. May seem overkill but we are in an exposed area and I tend to be a belt and braces chap.

Posted By: tonyDid you get planning permission?

Yes Was pretty straight forward but was called in to committee by a local councillor but her objection was thrown out in minutes after positive support for the application by others and she then withdrew her objection.

I like that. Looks very smart. Do you mind me asking a rough estimate of costs?

solar PV DNO export limit.

revor — Mon, 04 Sep 2023 18:51:47 +0100

Posted By: gustyturbineI like that. Looks very smart. Do you mind me asking a rough estimate of costs?

Â£750 for the mounting system about Â£100 for blocks and cement about Â£2k for panels. That was in 2020.

solar PV DNO export limit.

jamesingram — Wed, 20 Sep 2023 20:27:20 +0100

RE DNO export limitations due to network restrictions .
If you've tried via G99 to get larger than 3.68kW export and no luck you can use a G100 exported limitation scheme.
Most inverters now have export limitation or control built in via CT clamp or energy meter.
Hybrid inverter certainly do and come with G100 certification.

solar PV DNO export limit.

djh — Wed, 20 Sep 2023 20:57:59 +0100

I just posted a comment to the Sunology thread, but whilst it is correctly recorded in the 'All Discussions' listing, the entire thread seems to have disappeared Presumably I did something stupid in formatting my comment that has blown up the **** site software Could somebody with more permissions take a look and fix it please?

(PS sorry for derailing this thread temporarily!)