MikeSharp01 Posted February 17, 2020 Share Posted February 17, 2020 When installing PV the local distribution network operator (DNO) needs to be told if the installation is more than 3.9Kw (ish). For those in the know the G59 form, which was the route for this communication, is now defunct and the new G99 process is order of the day for grid connected PV schemes above 3.9Kw, ours will be around 7.5Kw so we need to go through the G99 process, via form A1-1 (simplified). Before I ring UK Power Networks I was wondering if anybody has been through G99 and can give me a heads up on how it was for you. I want to avoid using more than one phase because of the extant cabling and the dangers of having using more than one phase across what it otherwise a domestic site. So I am going to try that approach first. One thing I have not provisioned for is the G99 relay I suspect I need in here somewhere, I guess it goes just after (on the way in) the incomer breaker? Although relays seem a lot less 'talked about' nowadays! Our schematic of 2017 is attached and I am also wondering how I might control this so I don't end up exporting the battery output or, more importantly, using it to charge the EV (our next car will be an EV) and then have nothing to get us through the night. I wonder if the various inverters are / some are able to cope with this complexity without active control? Any observations gratefully accepted - perhaps I have more than 2 problems? Link to comment Share on other sites More sharing options...
Ferdinand Posted February 18, 2020 Share Posted February 18, 2020 Slightly tangential MIke, however for my 10kWp array (installed pre-G99), the installing company did all the paperwork including the grid connection forms. Are you self-doing all of this, or can you draw on a similar resource? F Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 18, 2020 Author Share Posted February 18, 2020 1 hour ago, Ferdinand said: Are you self-doing all of this, or can you draw on a similar resource? I am trying to do it all myself, it looks like I can other than the MCS bit - I will be seeking an MCS sign off but I want to do the install myself. 1 Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 18, 2020 Author Share Posted February 18, 2020 Just discovered another wrinkle it looks like the power companies are running, if you have a battery installation your export tariff is set at 50% of the normal because they cannot determine if your export is coming from grid derived energy you put into the battery! Link to comment Share on other sites More sharing options...
Stones Posted February 18, 2020 Share Posted February 18, 2020 12 hours ago, MikeSharp01 said: Before I ring UK Power Networks I was wondering if anybody has been through G99 and can give me a heads up on how it was for you. I want to avoid using more than one phase because of the extant cabling and the dangers of having using more than one phase across what it otherwise a domestic site. So I am going to try that approach first. One thing I have not provisioned for is the G99 relay I suspect I need in here somewhere, I guess it goes just after (on the way in) the incomer breaker? Although relays seem a lot less 'talked about' nowadays! It's a few years since we installed 7.2 kWp of PV on our last house, and had to go through the G59 process. Initially, the DNO, having looked at the proposal, came back and said we will need to reinforce the grid, fit a relay at a cost of £000's. The PV installers went back to them with the spec of the larger G59 compliant inverter which had all the gubbins required within. DNO said fine, no need to reinforce or fit relays, and the install was basically the same as a 3.68kWp array- Panels to DC isolator to inverter to AC isolator to CU. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 18, 2020 Author Share Posted February 18, 2020 10 minutes ago, Stones said: Initially, the DNO, having looked at the proposal, came back and said we will need to reinforce the grid, fit a relay at a cost of £000's. Yes that looks like the way things were but I hope that these days they are bit more relaxed. There is always hope! Link to comment Share on other sites More sharing options...
Jeremy Harris Posted February 18, 2020 Share Posted February 18, 2020 1 hour ago, MikeSharp01 said: Just discovered another wrinkle it looks like the power companies are running, if you have a battery installation your export tariff is set at 50% of the normal because they cannot determine if your export is coming from grid derived energy you put into the battery! This really shows a level of ignorance on the part of whoever makes these rules that is beyond belief. It is very easy to ensure that a battery system never exports to the grid, and apart from anything else, very few domestic consumers would ever want their precious stored energy from their battery system to accidentally flow to the grid. The battery systems I've been looking at all ensure zero export to the grid from the battery system. Not hard to do, as the battery system has to measure the entire power coming in, or out, at the incoming feed to the property, anyway. It uses that to do its primary function of limiting import during peak tariff periods. The usual method seems to be fitting a current transformer around the incoming tails, in the same way as a PV diverter would, to detect the direction and magnitude of the current coming in or out of the incoming supply. In addition, a battery system needs to know the total power being generated by the PV system, so will normally use another current transformer clipped around the PV system AC feed. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 18, 2020 Author Share Posted February 18, 2020 2 minutes ago, Jeremy Harris said: This really shows a level of ignorance on the part of whoever makes these rules that is beyond belief. Yep, I read it in a Which report (https://www.which.co.uk/reviews/solar-panels/article/solar-panels/solar-panel-battery-storage) but I have not had time to confirm it - it seems daft, as you say, and it may be that they have it wrong or I misread it. Link to comment Share on other sites More sharing options...
joth Posted February 18, 2020 Share Posted February 18, 2020 1 hour ago, MikeSharp01 said: Yep, I read it in a Which report (https://www.which.co.uk/reviews/solar-panels/article/solar-panels/solar-panel-battery-storage) but I have not had time to confirm it - it seems daft, as you say, and it may be that they have it wrong or I misread it. Try the SEG league table: https://www.solar-trade.org.uk/resource-centre/advice-tips-for-households/smart-export-guarantee/ The battery FAQ there is fairly comprehensive and says that while the SEG does not oblige suppliers to pay anything for non renewable energy sources, currently none are putting additional limits on if you have battery storage. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 18, 2020 Author Share Posted February 18, 2020 1 hour ago, joth said: https://www.solar-trade.org.uk/resource-centre/advice-tips-for-households/smart-export-guarantee/ Interesting link - thanks for that. Link to comment Share on other sites More sharing options...
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