How much does DNO approval cost / is it worth it for my system

ccbrowning

Thanks - perhaps this installer is just busy and was trying to find a way to fob me off.

70sbudgie

ccbrowning said:

Is there a range? I spoke to an installer who told me to speak to the DNO first and it could be up to £9k, to go over 3.68kW. I have an existing 3.4kW system and want to expand and add a battery.

Can you just get an inverter that limits export?
https://www.enwl.co.uk/get-connected/apply-for-a-new-connection/generation-and-storage/micro-generation-and-storage-connections/

Integrated micro-generation and storage

Working in partnership with the ENA, a relaxation was written into G99. This relaxation has primarily been developed where a customer is wishing to combine a G83/G98 generator with an Energy Storage Device.

To qualify, the following conditions must be met:

• Total generation capacity installed should not exceed 7.36KW (including battery storage)

• All generators should be connected via a Type approved G83/G98 protection device

• The maximum export should be limited to 3.68KW per phase utilising a Type approved EREC G100 device

• The system should not generate during a power-cut (island mode) 

Ignore the bit about G83, that is the old terminology.

G99 is like a check list of things that if you can demonstrate you comply with, the DNO won't  charge you for them to check. Less than 1MW is category A. Batteries are currently exempt from some of the items on the list. 

I think the list given is to allow installations that would normally be G99, to be treated at G98. So you won't be charged if you can say yes to the checklist:  combined battery storage and pv inverter doesn't exceed 7.36kW; MSC installation; G100 compliant export limitation device; don't operate in island mode.

G100 is the guidance for export limitation schemes (in the way that G98 applies to domestic scale generation). It is usually installed where the inverter can export more than the allowed capacity.

If your battery and pv are DC connected, the inverter will limit the export so you won't need additional export limitation.

Though I suspect the wording above is to allow people with FITs installations to add batteries without compromising their FITs generation payments - i.e. they will be AC coupled.

I'm not sure what the £9k would be for unless it is as @ABrass says and it is to upgrade your single phase supply to 3 phase. 

How big a battery are you looking to connect? (Sorry if you've said above).

Edit: if in doubt, give them a call and ask to speak to an engineer.

ccbrowning

Thanks @70sbudgie! We're looking at adding 9.5kW of battery storage and doubling our PV to take up into the 7.x range.

70sbudgie

ccbrowning said:

Thanks @70sbudgie! We're looking at adding 9.5kW of battery storage and doubling our PV to take up into the 7.x range.

Do you mean 9.5kWhrs of battery storage? Or a charge / discharge rate of 9.5kW?

With a set up of that size (the latter) you may need a 3 phase system!

ccbrowning

A 9.5kWh storage - https://www.deegesolar.co.uk/givenergy_9-5kwh_battery/

We won't send much to the grid at all due to the load, except maybe some summer days if we don't use the computers (100% electric house, gshp, I work in IT, etc.)

SevenOfNine

Our installer charged a total of £175 for DNO application (G99) but that has also included insurance fee (to cover protection of our 1st payment deposit & we have the policy). 

Martyn1981

ABrass said:

ccbrowning said:

Is there a range? I spoke to an installer who told me to speak to the DNO first and it could be up to £9k, to go over 3.68kW. I have an existing 3.4kW system and want to expand and add a battery.

Can you just get an inverter that limits export?
https://www.enwl.co.uk/get-connected/apply-for-a-new-connection/generation-and-storage/micro-generation-and-storage-connections/

Integrated micro-generation and storage

Working in partnership with the ENA, a relaxation was written into G99. This relaxation has primarily been developed where a customer is wishing to combine a G83/G98 generator with an Energy Storage Device.

To qualify, the following conditions must be met:

• Total generation capacity installed should not exceed 7.36KW (including battery storage)

• All generators should be connected via a Type approved G83/G98 protection device

• The maximum export should be limited to 3.68KW per phase utilising a Type approved EREC G100 device

• The system should not generate during a power-cut (island mode) 

The only reason it might cost £9k is if you need to install 3 phase power. And that seems like an expensive quote for that.

Many modern inverters can cap export, it's a common feature now.

3phase will depend largely on the distance, and any groundworks. For myself, in a suburban surrounding, I was quoted £14k, for a direct cable from the substation about 100+ metres away. Obviously not worth it for my circumstances. But my sister in a rural location, who was ultimately able to install 10.3kWp of solar on her south facing roof, and switching from diesel boiler to ASHP, got 3phase for under £2k, as the pole across the road from her had 3phase already (for the nearby farm complex), so it was an easy job, and just 20metres of cable needed replacing, with no excavation etc, as it was just pole to side of house, in the air.

70sbudgie

I have heard of some sort of grant that completely covers the cost to upgrade to 3 phase (in the NW area). But I haven't found anything to back up the one comment. 

NoobSolar

Forget about 3 phase. Dno approval for g99 is generally free for what you are asking for. Phone them - they won't bite. Mine, through London power networks, for a very similar system (see below my message) was free and they generally are.

The reason the DNO express the possibility of charges is for situations where much bigger and more grown-up things are taking place requiring site assessments, etc.

More importantly, your inverter is way too small there. If there is a potential degradation or mismatching issue due to the different aspects, get a solaredge optimiser on each panel. Sorted.

Martyn1981

70sbudgie said:

I have heard of some sort of grant that completely covers the cost to upgrade to 3 phase (in the NW area). But I haven't found anything to back up the one comment. 

Hi, not quite what you asked, but there has been growing pressure for a few years now, for 3phase to be standard or at least seriously considered for new build estates, and major local overhauls. The reason being, as we often discuss on here, DNO issues with larger export, and also potentially import, as PV gets larger, BEV sales increase, and heatpump rollouts.

80-100A single phase supplies are capable of coping with a lot of PV / BEV / batt / HP issues, but 3phase would make life easier, and allow for growth - just like the bigger PV and DNO permission issues that crop up on here all the time. Going back 10+yrs, a good/large PV install was 4kWp, with 250Wp panels. Now we are closing in on 400Wp of a similar size, that lifts the figure to 6.4kWp, which is just a bit too big for a 3.68kW cap, and in my situation with smaller roofs, but two (E/W) my 5.58kWp scaled up would be about 9kWp today.

So there may well be forms of support somewhere for transitioning, as you seem to recall.