christianscook Posted September 18, 2022 Share Posted September 18, 2022 Hi All My name's Christian, I'm new here and hoping to pick your brains I've just had a fresh install, 4.5kw of panels with a solis rhi-5k-48es-5g 5kw inverter (with export limit set to 3.6kwh) and I have a few questions I currently have 11 panels over 2 strings. 1) does the fitter need to apply for dno g98 or do I need to do that myself? They told me I'd only get and MCS cert and wont be touching dno as they don't need to (doesn't seem right to me) 2) with the above in mind am I allowed to connect a battery up myself? 3) again with above in mind am I allowed to add another panel myself to either of the strings and not mess up SEG 4) as all the panels are across 2 strings can I combine them all onto 1 (if one is shaded at the moment then they will all be) and setup four new panels pointing east on the now spare inverter DC input? Looking forward to hearing your thoughts Thanks Link to comment Share on other sites More sharing options...
Nickfromwales Posted September 18, 2022 Share Posted September 18, 2022 DNO should have been petitioned to see if you could export the lot!! The DNO would probably have given you the green light for that tbh as you're not massively over the base threshold ( circa 3.6 iirc ). They ( DNO ) would ask YOU for the export limitation as part of your application to install more than that allowance, and I'm pretty sure your fitter cannot just dial a higher power setup down and deem this compliant, independently, afaik. I think you should disconnect this until you have all this scrutinised, understood and in proper order. Over 3.6 should have provoked your fitter into an immediate and automatic DNO application, before even taking a deposit or ordering equipment, let alone buying it and fitting / commissioning it. Adding AC coupled batteries ALSO needs to be part of that application, plus adding more panels. Only DC coupled PV panels and batteries on the DC side of a hybrid inverter evade this requirement. Sounds like a cause for concern to me, sorry. 2 Link to comment Share on other sites More sharing options...
Nickfromwales Posted September 18, 2022 Share Posted September 18, 2022 If there is any shading, optimisers should have been fitted to get this to a standard that would pass MCS. What shading do you refer to? 1 Link to comment Share on other sites More sharing options...
christianscook Posted September 18, 2022 Author Share Posted September 18, 2022 Re shading all I meant is all the panels are in the same place so as a whole the are either in the sun or not It is a hybrid inverter so batteries would be DC coupled? I Link to comment Share on other sites More sharing options...
Nickfromwales Posted September 18, 2022 Share Posted September 18, 2022 4 minutes ago, christianscook said: Re shading all I meant is all the panels are in the same place so as a whole the are either in the sun or not It is a hybrid inverter so batteries would be DC coupled? I OK. Batteries and panels on the DC side can be to any scale, but export limitation needs to be specified by the DNO and that instruction is followed by your installer. You would ( should ) have to tell the DNO of the max output from the hybrid ( 5kw in your case ) and have had permission for that before commencing. Is the rating for 5kw of PV and an additional (x)kw for batteries? Hybrids are usually dual input, so panels on one input and batteries on the other. Therefore if you split the panels to have a dual-string arrangement, where will your batteries connect? Sounds like your fitter has gone for the guaranteed sale with his own, self-dispensed means of mitigation, insuring against your possible refusal from the DNO and his loss of a sale. Worst case is the inverter going to default and throwing the full 5kw to the grid eg in the event of an equipment failure / malfunction. Time to go ask some awkward questions...... 1 Link to comment Share on other sites More sharing options...
TW9 Posted September 19, 2022 Share Posted September 19, 2022 One thing to add to Nick's excellent advice, the application you need is a G99 (not a G98) as your inverter is over 3.68kW. It doesn't matter that it's export limited. As Nick said, this has to be approved before connecting the system to the grid. 1 Link to comment Share on other sites More sharing options...
christianscook Posted September 19, 2022 Author Share Posted September 19, 2022 The inverter is g100 approved so does that not help me out at all? Link to comment Share on other sites More sharing options...
christianscook Posted September 19, 2022 Author Share Posted September 19, 2022 The inverter has its own DC input for the battery (so 2 PV strings plus one battery) Link to comment Share on other sites More sharing options...
Marvin Posted September 19, 2022 Share Posted September 19, 2022 (edited) Hi Christian We applied for a 5.12kW installation as it was connected to the grid. Discussing with the DNO, they told me they considered the amount I needed permission for was the maximum the Inverter could export: 6kW (In our case no AC battery supply). They were not concerned as to how many panels were connected, just the maximum the inverter could export. Furthermore, the inverter technical info says I can connect up to 7.9kW of PV but it will still only export a maximum of 6kW. 33 minutes ago, christianscook said: The inverter is g100 approved so does that not help me out at all? That's like saying your car has an MOT, but you haven't got a driving licence: suitable to use connected to the grid but no permission. Good luck M Edited September 19, 2022 by Marvin Link to comment Share on other sites More sharing options...
christianscook Posted September 19, 2022 Author Share Posted September 19, 2022 (edited) So essentially I need the inverter either swapping for a 3.6kwh or it needs switching off until a successful g99 has returned which is likely to be accepted as we can always rate limit the device if the grid isn't upto 5kwh? *But even if it gets swapped I'll need g98 Edited September 19, 2022 by christianscook Link to comment Share on other sites More sharing options...
Dillsue Posted September 19, 2022 Share Posted September 19, 2022 43 minutes ago, christianscook said: So essentially I need the inverter either swapping for a 3.6kwh or it needs switching off until a successful g99 has returned which is likely to be accepted as we can always rate limit the device if the grid isn't upto 5kwh? *But even if it gets swapped I'll need g98 Technically all correct, but.... With only 4.5 kw of panels youre unlikely to cause anyone any problems so I wouldn't rush to disconnect. Id ask youre installer why he installed a 5kw inverter as a quick look at a Solis 3.6 inverter says it can have 7kw of DC input. Fitting a 3.6kw inverter would keep you within the DNOs G98 limit and you wouldnt have the issues youre asking about. If you want to keep the 5kw inverter then youll likely need a G99 application with a G100 supplement to cover the export limitation. Our DNO charges to witness the export limitation is set correctly! Id put this back to youre installer to answer a few questions!! Link to comment Share on other sites More sharing options...
christianscook Posted September 19, 2022 Author Share Posted September 19, 2022 I'm guessing I'd only be able to see 3.6kw of the PV output tho tops? Link to comment Share on other sites More sharing options...
joth Posted September 19, 2022 Share Posted September 19, 2022 Hopefully doesn't come to it, but I'd suggest making yourself familiar with the MCS complaints process now so you can ensure your next steps support it if it becomes necessary. https://mcscertified.com/complaints-compliance/ "Non-compliance with relevant installation Standards" seems relevant. MCS don't add much legal clout to put stuff right beyond normal consumer rights, but fear of loss of their certificate is the main concern for the installer. Link to comment Share on other sites More sharing options...
Pocster Posted September 19, 2022 Share Posted September 19, 2022 Tbh if you plan a battery soon ( ish ) the export rate you are permitted becomes far less important. I can only export 3.6kw but I can store 23kw . Initially my plan was to export everything I could ; now it’s to store everything I can . Export rate is pretty poor ( 4.1p kw ) - so better to store . Link to comment Share on other sites More sharing options...
christianscook Posted September 19, 2022 Author Share Posted September 19, 2022 Really useful Joth. Yeah I don't plan to store much I just want it to all be legit/legal To clarify it would be the fitter who sends the application in for DNO 98 or 99 and not me? Link to comment Share on other sites More sharing options...
joth Posted September 19, 2022 Share Posted September 19, 2022 16 minutes ago, pocster said: Tbh if you plan a battery soon ( ish ) the export rate you are permitted becomes far less important. I can only export 3.6kw but I can store 23kw . Initially my plan was to export everything I could ; now it’s to store everything I can . Export rate is pretty poor ( 4.1p kw ) - so better to store . Not sure how this is related? Even if you get no export rate (and no MCS certificate) it's still a legal requirement to go through G99 approval before connecting a larger sized inverter to the grid. That's what's at issue here. (the MCS reference is purely about getting them to add pressure to put it right, seeing as it's an MCS installation anyway) (But as others have said the oversizing here is very slight so in practical terms little risk, it doesn't justify not doing it on a paid installation) Link to comment Share on other sites More sharing options...
Pocster Posted September 19, 2022 Share Posted September 19, 2022 12 minutes ago, joth said: Not sure how this is related? Even if you get no export rate (and no MCS certificate) it's still a legal requirement to go through G99 approval before connecting a larger sized inverter to the grid. That's what's at issue here. (the MCS reference is purely about getting them to add pressure to put it right, seeing as it's an MCS installation anyway) (But as others have said the oversizing here is very slight so in practical terms little risk, it doesn't justify not doing it on a paid installation) Yes agree with the Gxx requirement. Just suggesting that exporting isn’t the be all and end all - though clearly the system needs to be installed with compliance. Link to comment Share on other sites More sharing options...
Dillsue Posted September 19, 2022 Share Posted September 19, 2022 1 hour ago, christianscook said: I'm guessing I'd only be able to see 3.6kw of the PV output tho tops? Yes, but thats what youve got now with your 5kw inverter limited to 3.6kw. Using the correctly G98 certified inverter saves you the G99/G100 application and cost Link to comment Share on other sites More sharing options...
SteamyTea Posted September 19, 2022 Share Posted September 19, 2022 Have you checked your installer is on the MCS database? Did you pay a lot for the installation? Did they show you an estimated annual yield for what you have paid for? 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now