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Martyn1981 wrote: »Hiya Roger, can I add some real life experience. This isn't meant as a criticism, more a follow on from our chats about going over 4kWp and the pro's and con's.
Hiya Roger, me again, sorry. Just an addendum, as co-incidentally today has turned out to be very interesting.
Firstly, loads of cloudburst spikes around 1pm, and whilst I don't hover over the monitors (honest) I did briefly see 3.6kW ESE + 1.5kW WNW, so a new record of 5.1kW for me.
These readings are from ENViR monitors reading off the TGM's via Optismarts, so very accurate.
Secondly, lots of sudden zero's around the same time coming from the WNW system. Quick check in the loft showed the SE2200 inverter 'warming up' after a shutdown, so a quick nose at the SB2500HF in the downstairs loo, showed a mains voltage fluctuating between 249V and 253V. The magic 253V (230V +10%) overvoltage figure. So it shut itself down.
Our voltage has always been a little high at around 240-244V, but perfectly acceptable. But over the last year (not me guv, honest) I've noticed it creeping up. Currently generating about 3kW and voltage 242V, so all over the place today. Will take a few mental notes this evening, once the evening peak is over.
Doubt this is due to SSEG's, the nearest house to us with PV is about 50 houses away, so Pi/r2, less gardens, roads and several parks, means nobody else within about 500 houses.
Oh well, such is life!
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
I'm looking at a 7kW system for my roof. I'm pretty sure I don't need building regs or planning as its on a roof I've just erected that's reinforced with rsj's(building regs). Several of the companies that have quoted aren't interested because of DNO regs. I'm not 100% sure what that means apart from more paperwork. Anyway been quoted £9K so far. They say i'm eligible for the first 15.44p upto 4kW then 13.99p after that.
Now I've read a hell of a lot before I registered on here and that doesn't sound right, isn't it 13.99p for the full lot?
System(hopefully) is 7kw ssw facing and 30 degree pitch, 6500kw expected generaton. Does that sound right for DerbyThe best things in life should always be free0 -
I'm looking at a 7kW system for my roof. I'm pretty sure I don't need building regs or planning as its on a roof I've just erected that's reinforced with rsj's(building regs). Several of the companies that have quoted aren't interested because of DNO regs. I'm not 100% sure what that means apart from more paperwork. Anyway been quoted £9K so far. They say i'm eligible for the first 15.44p upto 4kW then 13.99p after that.
Now I've read a hell of a lot before I registered on here and that doesn't sound right, isn't it 13.99p for the full lot?
System(hopefully) is 7kw ssw facing and 30 degree pitch, 6500kw expected generaton. Does that sound right for Derby
Hiya pvforme, the 6500kWh pa estimate looks pretty solid, assuming no shading. Not sure how to guesstimate the price, but a low 4kWp price was £5k (not sure if that's possible at the moment), so £5k divided by 4kWp then multiplied by 7kWp = £8,750, so a reasonable number?????
You are spot on about the 13.99p bit. You get the tariff for the band that the install sits in. So you'd get the 4-10kWp tariff for all of it. Unless you installed and registered 4kWp, then later on added 3kWp. That way you'd get the 4kWp rate for the first install, then the 4-10kWp rate for the extension (as it would be added to the first bit). For all the hassle and extra work, hardly worth bothering for an extra 1.5p on 4/7's of the generation.
Lastly, the DNO bit is serious, not just extra paperwork. They will allow a system to be installed prior to them being notified, if it is smaller than 3.68kW, or capped so that it can't exceed 3.68kW. (I'm talking about a normal domestic single phase supply.)
To get proper use of a 7kWp system, that will be able to sustain levels of generation of about 6.3kW (90% once the panels get hot and performance drops off - perhaps 2mins), you'll need an inverter of around 6kW or more, and that will need prior approval from the DNO.
The DNO may refuse, probably will refuse(?) to allow you to go over 3.68kW. So ask them first for their thoughts. To get permission the installer will have to apply for permission beforehand.
Loads of stuff in the above, just ask me which bits, or all, you're not sure about.
Best of luck.
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Mart,
My 2 systems add up to 4kWp. 2 separate inverters so i'm not capped at 3.68kWp. Should I have informed DNO?
tunnel2 kWp SEbE , 2kWp SSW & 2.5kWp NWbW.....in sunny North Derbyshire17.7kWh Givenergy battery added(for the power hungry kids)0 -
Mart,
My 2 systems add up to 4kWp. 2 separate inverters so i'm not capped at 3.68kWp. Should I have informed DNO?
tunnel
Hiya, that's a damn good question, thrown me completely.
Firstly let me stress I'm regurgitating a lot of stuff I've read and learned, but no expert whatsoever.
Secondly, the difference between 3.68kW and a 4kWp system is so small, that it used to be ignored (I think).
Thirdly, not sure about all DNO's, but WPD used to accept inverter efficiency, so no pre-notification needed if the inverter was 92% or less efficient (for a 4kWp system).
Just checked my 'solar folder' and the link to WPD that showed the calculation using the efficiency rating of the inverter, is now dead. I can't find a similar calculation now, but found this instead:
http://www.westernpower.co.uk/Connections/Generation/Installation/G83-2-Stage-1/Generator-Ratings.aspx
It now simply says:-
"For example, a single phase PV solar installation that uses a 4kW inverter is deemed to have a rating of 4,000 ÷ 230 = 17.39A, which is just over the 16A per phase threshold*."
Fourthly, your extension was some time back now (8 months or so?) so your installer would have notified the DNO within about a month, so they must have accepted (approved) it by now.
Fifthly, it's too early for trick questions!
We were chatting about this quite a while back, and I think it was Eric that pointed out that 4kWp installs used to go through without anyone caring, even before they became capped at 3,680W. Things seem to have toughened up a lot in the last year.
Only my opinion, but I really don't think they'll care, and I wouldn't bother questioning now, given that your systems are all up and running. If you're curious, have a look at the euro efficiency ratings of your inverters, multiply these against the Wp of each system and see what the total is.
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Thanks, My thinking was if they weren't bothered then, then it should be ok by now, you just never know sometimes. I guess the times when i'm generating over 3.68kWh would be few and far between so shouldn't matter so much.
Saying that, it has happened 3-4 times in the past couple of weeks and I've had nothing blow up/shut down....YET
Tunnel2 kWp SEbE , 2kWp SSW & 2.5kWp NWbW.....in sunny North Derbyshire17.7kWh Givenergy battery added(for the power hungry kids)0 -
Martyn1981 wrote: »
We were chatting about this quite a while back, and I think it was Eric that pointed out that 4kWp installs used to go through without anyone caring, even before they became capped at 3,680W. Things seem to have toughened up a lot in the last year.
Not quite what I said
Our 4.00kWp (same for panels & inverter) did have to be referred to DNO (WPD around here) but that was no great hardship. Installer took care of the paperwork - which I believe he said was one fairly simple form - and permission was granted well before the panels arrived (they'd been in short supply that month and we had to wait for a boatload to arrive).
In our particular case, we never anticipated any problem because our house is served by its own dedicated transformer from an 11kV power line in the adjacent field. Hard therefore to imagine any scenario where a supply cable could ever have been 'overloaded'. Unlikely that anyone else would ever have that degree of 'perfection' although I find it still pretty hard to see how a limit as low as 16A could ever be justified. Most houses have an incoming mains fuse of at least 60A (100A is quite common) and one would hope that the cables supplying such a fuse would be adequate for that. Possible of course that a hundred houses in the same street all exporting 16A might be a problem at the substation but I've never seen a street quite like that.NE Derbyshire.4kWp S Facing 17.5deg slope (dormer roof).24kWh of Pylontech batteries with Lux controller BEV : Hyundai Ioniq50 -
Not quite what I said
Sorry Eric. I misunderstood. When you'd said that there was no problem with permission, I'd mistakenly assumed (never, never assume Martyn) it was post install, not pre-install.
Apologies for mis-quoting you.
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Martyn1981 wrote: »
Apologies for mis-quoting you.
Mart.
Not a major problem - I just wanted to avoid anyone charged with illegally installing a large system claiming I'd said it was OK
I'm sure I vaguely recall somebody else (but no idea who) saying they'd broken the 16A rule and had been 'forgiven'; no doubt I was being confused with whoever did say that ?
But no need for anyone to risk that : my installer said it's a simple & straightforward procedure to apply for permission which is seldom refused. Can't understand why any other installer would run away from being asked to do the same.NE Derbyshire.4kWp S Facing 17.5deg slope (dormer roof).24kWh of Pylontech batteries with Lux controller BEV : Hyundai Ioniq50 -
I'm looking at a 7kW system for my roof. I'm pretty sure I don't need building regs or planning as its on a roof I've just erected that's reinforced with rsj's(building regs). Several of the companies that have quoted aren't interested because of DNO regs. I'm not 100% sure what that means apart from more paperwork. Anyway been quoted £9K so far. They say i'm eligible for the first 15.44p upto 4kW then 13.99p after that.
Now I've read a hell of a lot before I registered on here and that doesn't sound right, isn't it 13.99p for the full lot?
System(hopefully) is 7kw ssw facing and 30 degree pitch, 6500kw (sic) expected generaton. Does that sound right for Derby
Chesterfield's generation shouldn't be that far from Derby's and I doubt my 17.5 deg S facing roof is hugely worse than a 30 deg one.
My annual generation is around 3500kWh so scaling up to 7kWP I'd expect to get around 6200.
So 7500kWh is certainly in right parish.
I agree that a 7kWP system should all be paid at the lower FIT rate. Unless of course you do what Martyn did and fit a 4kWP system first then add a second system of 3kWP at a later date (and I don't think there's any rule that would stop you putting all 7kWP worth on the roof at once, installing & registering 4kWP immediately then registering the 'extension' a couple of weeks later - but seek proper advice rather than relying on my guess !)NE Derbyshire.4kWp S Facing 17.5deg slope (dormer roof).24kWh of Pylontech batteries with Lux controller BEV : Hyundai Ioniq50
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