G59 DNO application process

MrSugarfr33

Well, against all odds and hoping for electricity prices to go up (to help with my break-even calculations) I decided to go for the solar panels and a Tesla battery. I know the battery prices probably don't justify the spend, given how much extra self generated energy I can use myself, but I hope to switch to some flexible tarrif like Octopus Agile and recover my money this way. Anyway, the system I am installing is 4.8kWhp (limited by size of the roof and dormer/velux windows) and DNO application is necessary. I wonder if anyone had a recent experience waiting for G59 approval to come back. I have been told it may take up to 8 weeks - I wonder how long other people had to wait?

Zarch

CTS applied for G59 on my behalf last week to Northern Power and NP told them there was now a £350 application charge. So something to bear in mind. Although it sounds like its still free at other providers. Maybe worth asking the question up front with your local power organisation?

One question, do you really need to apply for G59. Would you lose all that much having a 3.68 inverter with 4.8kWh worth of panels?

With a 3.68 inverter there is no DNO required despite having 4.8 of panels.

Only likely on the very of sunny days you'll be getting the max from you 4.8 worth of panels..... and with efficiency losses, maybe 15%, you'd be down near 4kWh anyway. Then on less than sunny days maybe under 3.68?

Just putting it out there. I've worked out that a 3.68 inverter on my soon to be installed multi aspect 5.1kWh system will be fine and likely on lose a few hundred W on those best sunny days. And really, only those very sunny days you likely wont be able to use it all, even with a battery..... some will likely go back to the grid.

Also, as the 3.68 inverter is about £100 cheaper, that's a bonus too. And unlikely you'll rake in the extra £100 back on current FIT prices, even over the long term?

Something to think about?

MrSugarfr33

I questioned that with my solar installer and they said DNO decides whether a G59 or G83 application needs to be submitted based on nominal power of the system (likely only achievable under laboratory conditions). The solar installer pays for the application. Also, Tesla battery will be configured to provide a 5kW peak output as opposed to standard 3.68kW peak output and apparently that also necessitates a G59 application...

Zarch

MrSugarfr33 wrote: »

I questioned that with my solar installer and they said DNO decides whether a G59 or G83 application needs to be submitted based on nominal power of the system (likely only achievable under laboratory conditions). The solar installer pays for the application. Also, Tesla battery will be configured to provide a 5kW peak output as opposed to standard 3.68kW peak output and apparently that also necessitates a G59 application...

You say the supplier pays for the application, but surely if there is a £350 charge you'll be the one who has to pay it in the end? The installer isn't going to give you £350 for free is he?

When you say 'nominal power of the system'. Are they using 4.8 of panels for that nominal power?

If you look at many UK circa 4.8kWh systems on PVoutput:
https://pvoutput.org/map.jsp?p=113&country=243&o=ss&d=asc
You'll see hardly any get past 4.0 kWh peak output even on the sunniest/best days. Yes, some of this is because they have 3.68 inverters limiting things, but those that do have larger inverters still never max out the panels true numbers?

With the Tesla battery, in reality how many times are you going to need more than 3.68kW at times when the sun isn't shining? You'd need a combination of devices in parallel consuming to get past 3.68?

If there is a £350 charge and with the larger inverter costing £100 more, personally I don't see the value in paying £450 extra as you'll never recoup that back in FIT.

But if the whole application is free and its only a £100 extra charge, then maybe its worth doing? I'd be surprised if you'd recoup the £100 through extra production/FIT, but the extra Tesla boost would be a nice to have I suppose.

Didn't know about the different Tesla configurations though, so something new to think about. :beer:

Martyn1981

MrSugarfr33 wrote: »

I questioned that with my solar installer and they said DNO decides whether a G59 or G83 application needs to be submitted based on nominal power of the system (likely only achievable under laboratory conditions). The solar installer pays for the application. Also, Tesla battery will be configured to provide a 5kW peak output as opposed to standard 3.68kW peak output and apparently that also necessitates a G59 application...

Hiya, that's not actually correct. If the install can't exceed 3.68kW export, then the installer notifies the DNO after the install for it to be registered.

If the system can theoretically export more than 3.68kW, then permission is needed beforehand from the DNO.

So let's say a 4.5kWp E/W install with half east and half west with a 4.5kW inverter, then that will never export more than 3.68kW, but will need DNO prior permission as the kWp and kW ratings are greater than 3.68kW and the DNO can't make assumptions about actual real life generation and export.

But a 4.5kWp due south facing, perfect pitch install with a 3.68kW capped inverter won't need permission.

However, as you say, the Tesla PWII does need permission due to it's ability to provide 5kW (7kW briefly?).

I think Tesla are working on this as their software might be capable of matching battery output exactly to import, thus minimising import and avoiding export, but I don't think they've got there yet, and it would still need approval and acceptance from the DNO's. Also, you might want to be able to export 5kW if there is some sort of peak price payment scheme in the future for grid support from demand side storage.

Exiled_Tyke

MrSugarfr33 wrote: »

I know the battery prices probably don't justify the spend, given how much extra self generated energy I can use myself, but I hope to switch to some flexible tarrif like Octopus Agile and recover my money this way.

I'm not sure this stacks up. If you take the cost of adding the battery and divide it by the total number of units it can realistically store over it's lifetime, then it needs to work out significantly less than the cost of buying electricity from the grid for it to be financially worthwhile. Every option I've personally looked at hasn't come near to this yet.

Zarch

Exiled_Tyke wrote: »

I'm not sure this stacks up. If you take the cost of adding the battery and divide it by the total number of units it can realistically store over it's lifetime, then it needs to work out significantly less than the cost of buying electricity from the grid for it to be financially worthwhile. Every option I've personally looked at hasn't come near to this yet.

Agreed. Plenty of similar chat in the Battery Storage thread.
https://forums.moneysavingexpert.com/discussion/5568536/on-grid-domestic-battery-storage

Battery prices just not low enough to justify for most.

MrSugarfr33

I spoke to the solar company again, apparently my inverter will be rated at 4kW so we have to wait for DNO to get back to us. It's been 3 weeks now, hopefully not much longer.