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Author Topic: DNO Witness charge  (Read 911 times)
Fen10
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« on: February 10, 2019, 04:56:58 PM »

I was just after a bit of feedback on others experience with DNO's and G59.
I've just had a new extension which has given me the opportunity to expand my 1.92Kw array I've had since 2011, I have room for only 6 more panels but as i'm also looking at getting a battery I want to max this out as much as possible, at present this is with 370W panels (but it's looking like some 400W may just be around the corner). So through my installer I applied for DNO permission to install the new array (total proposed onsite capacity 4.14Kw) plus a battery. They have just refused this and will only accept a export limiting solution which i'm ok with, but the sting in the tail is they are asking for £1080 to witness test the installation, my installer says they are usually only on site for 20mins.

First I was very surprised they rejected it for being just 460W over their limit (i would have half expected it if it had been for a 5Kw or 6Kw array), i'm looking to internally utilise all power and can't ever see 3.68Kw being exported let alone 4.14Kw, that and the charge is making me think it's more a money making scheme or an attempt to put people off, I don't know how they can justify that charge!

I know I could just accept the 3.68Kw limit but I don't want to because as well as the battery I also have plans for an EV and also may have the opportunity to further expand the PV in the future so wanted to get the max capacity on this new extension as once the panels are in they won't be changed in the future and I want the max array I can fit to support these plans.
This project is financially stretching for me and £1080 was something i hadn't budgeted for.

What are others experience with DNO charges, is this price along the lines of what others have been subject to?

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stannn
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« Reply #1 on: February 10, 2019, 08:01:02 PM »

Fen10 I have removed your second post linking to another supplier. Remember, this forum is paid for by Navitron who are in the solar panel business.
Stan
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2.45 kWp PV (Navitron supply), 40 evacuated tubes (Navitron supply), Clearview 650 log burner with back-boiler heating cottage and water, 2 off 50W border collies, 1 off 35W cat, 1 off 25W cat.
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« Reply #2 on: February 10, 2019, 08:54:14 PM »

Fen10,

If you go through my thread 'More PV at Courtiestown' you'll see I encountered the issue of my DNO, SSE, wanting to charge £585 to witness my installation unless installed by an 'approved' installer.

I have reservations about any witness test being necessary if appropriately approved equipment is used for the install. As my 1.675kW of panels, DC isolator, inverter, AC isolator, TGM and cabling are all 'approved' and is clearly working I really can't see what a DNO inspection would prove.

I intend adding a further expansion shortly but this will be done in conjunction with a Home Energy Manager 2.0 set-up so that the output from the property will be limited to the 1.675kW extension the DNO agreed with in my original application.

I am more than willing to be convinced as to the precise reason a DNO feels the need to conduct a witness test. The only difference I can see between this and a G83/ 2 install relates to the certification of the inverter fitted.

Regards

Richard
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1.28kW on a Lorentz ETATRACK1000 + 1.44kW/ SB3000TL-21 (FIT), 1.28kW/ SB1700 (ROO/FIT). CTC GSi12 heat pump/Ecosol/Flowbox 8010e/Gledhill ASL0085 EHS/3off Navitron 4720AL Solar ET & Immersun T1060/T1070/T1090. 3.375kW/ SMA SB3600TL-21 and a Sunny Island 4.4M-12 c/w 15.2kWh battery and a Renault Zoe.
nowty
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« Reply #3 on: February 10, 2019, 09:10:20 PM »

Fen10, welcome.

Its first worth looking at the rules, DNOs websites are difficult to understand and the rules keep changing.

First of all, it does not matter how many kW of panels you have, the DNO is not interested. Itís the inverter power that matters to them, even if there are not enough panels to give out that power or you set a limit on the inverter, it still matters to the DNO. Don't ask why, it just is.

So say 6kW of panels and a 3.68kW (16 amps) G83/2 inverter and you donít need to ask permission, just notify within 28 days.

The other possibility is you have a 3.68kW hybrid inverter (DC coupled battery and PV), this is the same as a standard G83/2 and as above you donít need to ask permission, just notify within 28 days.

There is a recent development (G83 Energy Storage Fast Track Connection Process) that if you have two G83/2 inverters (one of which is an AC coupled battery storage inverter) and it does not exceed 7.36kW (32 amps), then as long as its G100 compliant (limited to 3.68kW export and you need docs to show that), then you can do as above and just notify within 28 days. The DNO reserves the right to refuse it and request you remove it if they are not satisfied with the docs.

If you have G83/2 inverters which add up to more than 3.68kW then itís a G59 application and you generally will need G100 compliant export limiting equipment. This is the expensive route you have already tried.

So your options without an expensive G59 application, are:
1)   Replace your current inverter with a hybrid 3.68kW inverter with batteries, only need to notify a standard 3.68kW G83/2 install. In fact as you already have a notified install, you might not even need to as your still in the same category.
2)   Replace your existing inverter with a larger 3.68kW G83/2 one to cover the existing and new panels. Add a second battery inverter and use the G83 Energy Storage Fast Track Connection Process.
3)   Do something like me (I would not recommend it) and add a separate Offgrid system. This way you can add what you like and only need to ask permission from yourself. The DNO can go whistlie.
« Last Edit: February 10, 2019, 09:18:07 PM by nowty » Logged

10kW of PV installed and 50+ MWh generated.
Usable battery storage of 45+ kWh.
Hot Water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground Source Heatpump.
220,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
Fen10
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« Reply #4 on: February 10, 2019, 10:48:00 PM »

thanks for the replies (sorry about the link!)

Nowty - that's a lot of info to take in!

My present setup is 1.92Kw array with a 2000Kw SMA inverter. The new setup will have a solar edge 2.2Kw inverter and a Modbus device to limit the export and a powerwall battery.

I don't know if I could combine the inverters as that may affect the FIT on the existing setup.

My understanding is that the Modbus will sit at the point of supply for the house measuring the export for the house as a whole, and if this exceeds 3.68Kw it will start to limit the 2.2Kw solar edge inverter, if this is the case the original 2K SMA inverter setup should be irrelevant.

The G83 Energy Storage Fast Track Connection Process you mention, does this setup sound like it qualifies for this?

Its my understanding, the proof of the Modbus limiting the export at 3.68Kw ( I don't know how they can test it as even on a sunny summers day i doubt it would reach that level very often) by witnessing it is what the DNO want their £1000 for.
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linesrg
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« Reply #5 on: February 11, 2019, 06:18:51 AM »

Fen10,

In my case the DNO have approved the 1.674kW extension but it just needs to be done through a G59/ 3 inverter.

Thus I donít understand why they need to witness anything. Either the inverter is type approved or it isnít. It is type approved. To my mind it defeats the purpose of type approval if it needs Ďtestingí to see that it does what it is meant to.

Regards

Richard
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1.28kW on a Lorentz ETATRACK1000 + 1.44kW/ SB3000TL-21 (FIT), 1.28kW/ SB1700 (ROO/FIT). CTC GSi12 heat pump/Ecosol/Flowbox 8010e/Gledhill ASL0085 EHS/3off Navitron 4720AL Solar ET & Immersun T1060/T1070/T1090. 3.375kW/ SMA SB3600TL-21 and a Sunny Island 4.4M-12 c/w 15.2kWh battery and a Renault Zoe.
paul149
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« Reply #6 on: February 11, 2019, 09:25:17 AM »

"2000Kw SMA inverter."  Awesome!!!!!!
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3.5 kWp (14 x Sanyo H250E01 + SB3000TL) 225' (SW) at 35' Pitch Lat 51.30' (Bristol) Installed cost £2.63/Wp (Nov 2011) now with solarimmersion and 250L unvented dhw (Almost Zero gas input for DHW from Apr to mid Sep)
nowty
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« Reply #7 on: February 11, 2019, 10:57:46 AM »

thanks for the replies (sorry about the link!)

Nowty - that's a lot of info to take in!

My present setup is 1.92Kw array with a 2000Kw SMA inverter. The new setup will have a solar edge 2.2Kw inverter and a Modbus device to limit the export and a powerwall battery.

I don't know if I could combine the inverters as that may affect the FIT on the existing setup.

My understanding is that the Modbus will sit at the point of supply for the house measuring the export for the house as a whole, and if this exceeds 3.68Kw it will start to limit the 2.2Kw solar edge inverter, if this is the case the original 2K SMA inverter setup should be irrelevant.

The G83 Energy Storage Fast Track Connection Process you mention, does this setup sound like it qualifies for this?

Its my understanding, the proof of the Modbus limiting the export at 3.68Kw ( I don't know how they can test it as even on a sunny summers day i doubt it would reach that level very often) by witnessing it is what the DNO want their £1000 for.


With your proposed system, it might qualify for the G83 Energy Storage Fast Track Connection Process, but I believe the process is meant for adding a battery only storage inverter which you are not. Also I don't know if ALL DNOs follow this process, mine Scottish and Southern do. Who is your DNO ?

With regards to combining inverters and FITs, yes you can do this but as everything goes through the same generation meter, your FIT provider can dilute your payment rate in the ratio of the old and new panels.


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10kW of PV installed and 50+ MWh generated.
Usable battery storage of 45+ kWh.
Hot Water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground Source Heatpump.
220,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
Solarchaser
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« Reply #8 on: February 11, 2019, 11:17:46 AM »

My thoughts would be to change your 2.2 inverter to a 1.6 inverter (if there is such a thing) and then you are under the 3.6kw g83 limit.

There's evidence from Australia that you are better to overspec the panels for the inverter, as the times when the panels will create full output to matched inverter are few and far between, and so a 1.5kw inverter will be more efficient with 2kw of panels, then a 2kw inverter with 2kw of panels.

All inverters that I've looked at recently allow an almost doubling of panel spec.
For instance I have 6600w of panels going to my 3600w "off grid" inverter.
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Pile-o-stone
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« Reply #9 on: February 11, 2019, 12:28:39 PM »

We were looking at adding a further 3kw to our existing 5.18kw array. The DNO said we would have to pay them £!500 to strengthen the system. In the end we decided to spend our money on other items.
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5.18 kWp PV system (3.68 E/W & 1.5 E).
Fen10
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« Reply #10 on: February 12, 2019, 12:09:50 AM »

My DNO is ukpower.

I think is is what happens when you have a monopoly.

Things might even be getting worse, Iíve been googling this issue and found the G59 is being replace in a few months by G99. Check the attached.

I donít know if this will affect us.

* Safari - 12 Feb 2019 at 00:10.pdf (160.73 KB - downloaded 47 times.)
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nowty
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« Reply #11 on: February 12, 2019, 04:25:17 PM »

My DNO is ukpower.

I cannot find anything on their website about a simplified energy storage process so your only option if you stay with G83 (or the new G98) is to go with my option 1.

Replace your current inverter with a hybrid 3.68kW inverter with batteries and add new panels to it, only need to notify a standard 3.68kW G83/2 install. As you already have a notified G83 install, debatable whether you really need to inform DNO, in fact it might be more complicated as you may need to fill in a decommission form for the old inverter.

Notify FIT provider of added panels to your generating equipment for them to reduce your FIT rate. You will be paid a lower amount but for more units generated so overall, your income wont change much.
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10kW of PV installed and 50+ MWh generated.
Usable battery storage of 45+ kWh.
Hot Water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground Source Heatpump.
220,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
sbchapman
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« Reply #12 on: February 13, 2019, 12:06:45 PM »

"You will be paid a lower amount but for more units generated so overall, your income wont change much"

Ignoring the roundtrip efficiency losses of DC-coupled storage on PV inverters, and just assuming additional capacity on a FIT-registered PV inverter....
The income will change but there isn't a linear impact. If I understand correctly the FIT licensee is required to apply a proportional reduction of the new generation figures, however the new configuration will have a lower specific yield due to inverter clipping, the impact will increase as more additional DC capacity added.

An example with ~very~ rough maths:
Before kWp additions:
4kWp system; 4000kWh/Yr, specific yield 1000kWh/kWp; Income (ignoring export):4000*50p = £2000/Yr
After kWp additions:
6kWp system; 5500kWh/Yr, specific yield ~920kWh/kWp; Income (ignoring export):5500*50p*(4/6) = £1833/Yr
[Where 4/6 is the proportional reduction of the overall generation to scale it to the original 4kWp system]

Edit: Obviously I've assumed worst case above using the 'golden' FIT rate, same principle applies to later systems, albeit the £££s impact will be less. And the impact will be greater where the original inverter configuration already has a >1 DC:AC ratio (eg 4kWp/3.6KVA inverter) if we assume 4kVA inverter systems haven't had G83/2 active setpoint of 3.68kW applied
« Last Edit: February 13, 2019, 04:13:39 PM by sbchapman » Logged

Thermal: 4x Schott ETC16
PV: 3.9 kWp (20xSchott Mono Perform 195Wp)
Boilermate Thermal Store
SMA SB400TL-20
Clearview Pioneer 5kW
Woodwarm 9kW
Windsmithy Arthur 6kW
1 anemometer (sadly no turbine)
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