Solar Panels UK - is it worth it?

[phil4]

I don’t think the Powerwall even has a setting to permit export from the battery.
My understanding is that it would only ever do that when part of the now defunct Tesla Energy Plan.

If you're permitted export by your DNO (I'm not), you can ask Tesla to enable export, you'd then gain an extra choice on the settings for export and could select solar only, or all. I'll be honest, I don't think PW exporting permission is a particularly common, probably because the kW can be quite high.

 

[ACarneiro]

If you're permitted export by your DNO (I'm not), you can ask Tesla to enable export, you'd then gain an extra choice on the settings for export and could select solar only, or all. I'll be honest, I don't think PW exporting permission is a particularly common, probably because the kW can be quite high.

Very interesting, I didn’t know that. Thank you.

Do you specifically need permission to export from the battery or is permission to export from solar enough?

You can limit the PW export to the same as the allowed solar export, after all…

 

[KennethS]

Very interesting, I didn’t know that. Thank you.

Do you specifically need permission to export from the battery or is permission to export from solar enough?

You can limit the PW export to the same as the allowed solar export, after all…

Not absolutely certain and it may vary by area and DNO. We had solar PV installed many years before the Powerwall. When PV was installed the DNO put a 3.4kW limit on export. When they gave permission for the Powerwall it reaffirmed that the 3.4kW limit should remain. My reading is they don't care from where the up to 3.4kW comes.

 

[btc1k]

So the new Outgoing Octopus rate seems to be live on my account.
They’re indeed buying juice from me at 15p/kWh!

Interestingly enough, when I tried to configure my Tesla Gateway with the new utility prices, it wouldn’t let me input the 15p sell-price for the off-peak slot. Errored with “Sell price should not be higher than buy price”.

Seems like even Tesla can’t quite believe it…

Mine accepted the new prices, no issue.

 

[phil4]

Very interesting, I didn’t know that. Thank you.

Do you specifically need permission to export from the battery or is permission to export from solar enough?

You can limit the PW export to the same as the allowed solar export, after all…

I think it depends on the DNO wording, mine clearly stated 5kW solar export, 0kW PW export.

If you send your DNO permission to Tesla, saying as you said above, they'll probably enable it for you. Unless there's some tell-tale phrase they're looking for/see that tips them off.

 

[Pink Duck]

They also configure Backup Gateway with the total permitted export, as seen through the TEG website status.

 

[ACarneiro]

I’m not sure that I’ll want the added charge/discharge cycles on my PWs so probably will park that idea for the time being.
But thank you for the information, all.

 

[Andy B]

They also configure Backup Gateway with the total permitted export, as seen through the TEG website status.

Any chance you have a screenshot of that, please?

 

[Pink Duck]

Textual capture of mine, redacted slightly:

Site name: **************
Backup capability: Backup Capable
Mode: Self Consumption
Backup reserve: 0%
Grid Code: 50Hz_230V_1_G99_2018_UK
Time zone: Europe/London
Customer version: 23.12.2 63bc46d8
Network: Wi-Fi, Ethernet, Cellular
Powerall: Part 3012170-05-E, Serial TG123095****R0
Site Export Limit: 13 kW ← This appeared after Tesla enabled Export to Grid option

Compliance 1

• Manufacturer: Telit
• Model: LE910C1-EUX (4G)

Compliance 2

• Manufacturer: LGIT
• Model: TWFS-B005D (WLAN)
• FCC ID: YZP-TWFS-B005D
• IC: 7414C-TWFSB005D

 

[ringi]

I'll be honest, I don't think PW exporting permission is a particularly common, probably because the kW can be quite high.

Until recently there was no economic case to export from a PW hence no justification to pay someone to fill in the paperwork.

 

[phil4]

Until recently there was no economic case to export from a PW hence no justification to pay someone to fill in the paperwork.

Where do you mean? At the DNO when granting it, or the person applying for G99 which I think you need to do? If it's the later, they'd be filling the form out anyway, so not sure an extra box is much effort.

I take your point though, no one likely to query it or challenge it.

 

[ACarneiro]

Well, I’ve sent an email to my DNO to ask anyway.
Although I’m not planning on doing it it’ll be good to know whether I even have the option should I change my mind…

 

[notmeguv]

I've had a quote from Otovo which includes Growatt battery and inverter. Growatt reviews on Trustpilot are not great. Seems to be mostly relating to app/software and lack of support. Any Growatt owners had any problems?

The quote is £11718 which includes...
16 x 425W Trina panels (8 east, 8 west)
1 x Growatt SPH 6000 inverter
1 x Growatt GBLI6532 6.0 kWh battery
1 x Growatt SPM-E smart meter

I asked about a larger battery and could have a Growatt AXE 10.0L (9.2 kWh) instead which would raise the overall cost to £12894.

The AXE batteries are modular/stackable so I assume it would be easy to add more later if desired.

How does that sound? Anything I should be looking at doing differently?

 

[thax1]

I've had a quote from Otovo which includes Growatt battery and inverter. Growatt reviews on Trustpilot are not great. Seems to be mostly relating to app/software and lack of support. Any Growatt owners had any problems?

The quote is £11718 which includes...
16 x 425W Trina panels (8 east, 8 west)
1 x Growatt SPH 6000 inverter
1 x Growatt GBLI6532 6.0 kWh battery
1 x Growatt SPM-E smart meter

I asked about a larger battery and could have a Growatt AXE 10.0L (9.2 kWh) instead which would raise the overall cost to £12894.

The AXE batteries are modular/stackable so I assume it would be easy to add more later if desired.

How does that sound? Anything I should be looking at doing differently?

Worth confirming with the installer on their expectations around the Growatt‘s behaviour during a power outage.
At the time I was getting the Tesla PW and Gateway, my installer stated that the Tesla solution was the only vendor they used that they had the power outage mode working as expected. Their other suppliers were ’awaiting firmware’ to enable this.

 

[phil4]

I've had a quote from Otovo which includes Growatt battery and inverter. Growatt reviews on Trustpilot are not great. Seems to be mostly relating to app/software and lack of support. Any Growatt owners had any problems?

The quote is £11718 which includes...
16 x 425W Trina panels (8 east, 8 west)
1 x Growatt SPH 6000 inverter
1 x Growatt GBLI6532 6.0 kWh battery
1 x Growatt SPM-E smart meter

I asked about a larger battery and could have a Growatt AXE 10.0L (9.2 kWh) instead which would raise the overall cost to £12894.

The AXE batteries are modular/stackable so I assume it would be easy to add more later if desired.

How does that sound? Anything I should be looking at doing differently?

Start with your normal max daily usage... no point having a 6kWh battery if you only use 2kWh or 20kWh... it'd answer your question about the 9.2kWh as well.

Old advice was to size for normal max usage minus lower usage.... but now I'd aim so for most days in winter (high use) the battery can carry you through the day.... but without paying for exceptional one off days (eg. Xmas) that only occur once a year. And then export all your solar.

Allow for the Max Depth of Discharge of the battery, ie if it's 80% then a 10kWh battery is actually 8kWh.

Next check the battery max import date, can you charge it in your cheap off peak period? 20kWh at 2.6kW max can't fully charge in 6 hours IO off peak.

As you can make a good return on selling solar at the moment, you should get as much as you can. Even without that, again get as much as you can.

 

[phil4]

Someone earlier mentioned that Octopus should have added some encouragement around peak times, to encourage use/savings.

My thinking was more about batteries, at the moment to maximise return I'm using 100% grid to power the house and exporting 100% solar. That grid power is in the IO cheap rate. But unlike with the IO car charging there's zero battery integration, so no aiming for cheap/clean slots. My guess is we'll see some movement on that sooner rather than later.

And yes, I do realise I've gone back to grid power, but the solar is at least benefiting the street/grid as a whole.

 

[notmeguv]

Start with your normal max daily usage... no point having a 6kWh battery if you only use 2kWh or 20kWh... it'd answer your question about the 9.2kWh as well.

Old advice was to size for normal max usage minus lower usage.... but now I'd aim so for most days in winter (high use) the battery can carry you through the day.... but without paying for exceptional one off days (eg. Xmas) that only occur once a year. And then export all your solar.

Allow for the Max Depth of Discharge of the battery, ie if it's 80% then a 10kWh battery is actually 8kWh.

Next check the battery max import date, can you charge it in your cheap off peak period? 20kWh at 2.6kW max can't fully charge in 6 hours IO off peak.

As you can make a good return on selling solar at the moment, you should get as much as you can. Even without that, again get as much as you can.

Thanks. I need to work out our average daily use but at a quick look and without charging the car, it seems to be around 10 - 14 kWh. So perhaps I should stick another AXE module on and go for a 15 kWh battery!

The AXE batteries are showing as 92% DoD so the 9.2 I quoted above was the useable figure for the 10 kWh battery. It looks like they have a max charge/discharge rate of 3kW so I should be able to fully charge even a 15kWh array with IO off peak.

Just need to work out if Growatt are worth going for or look for something else.

 

[yessuz]

I am also on 15p per kwh export ;D

for those with 3 phase supply - can you get separate meters on each phase?

Pylon US3000C is 3.5 kwh, can discharge (and charge) at 3 KW... can stack...

 

[yessuz]

I've had a quote from Otovo which includes Growatt battery and inverter. Growatt reviews on Trustpilot are not great. Seems to be mostly relating to app/software and lack of support. Any Growatt owners had any problems?

The quote is £11718 which includes...
16 x 425W Trina panels (8 east, 8 west)
1 x Growatt SPH 6000 inverter
1 x Growatt GBLI6532 6.0 kWh battery
1 x Growatt SPM-E smart meter

I asked about a larger battery and could have a Growatt AXE 10.0L (9.2 kWh) instead which would raise the overall cost to £12894.

The AXE batteries are modular/stackable so I assume it would be easy to add more later if desired.

How does that sound? Anything I should be looking at doing differently?

I have Growatt Inverter with Pylon batteries, bought via Otovo.

I got same inverter - no issues whatsoever. and Otovo was very nice to work with.. BTW - did you use my Otovo referal?

p.s. my system is:
20 x trina solar panels (east west, 8 kwp total)
6 kw growatt SPH6000 inverter
3 x 3.5 kwh pylon batteries. these are stackable/modular

 

[WannabeOwner]

So perhaps I should stick another AXE module on and go for a 15 kWh battery!

If that means you don't actually run it to 0% on each cycle it would leave you some come-in-handy for a power cut. Unless you have a very unreliable supply it will most likely only be a side-benefit.