Mr Blobby Posted February 16 Share Posted February 16 We have the standing seam roof up and scaffold is still in place. I have the S5 clamps to attach the panels to the seams. We are putting 20 panels on the East and South-East roofs and then 7 on the SW facing flat roof garage (so we don't spoil the roof at the front). Cost of panels is falling like a stone so we can now get 27 Aiko 445 all black N type panels for a whisker over two grand. and then about 550 quid for renusol buckets. So about 2600 for materials. Solar installer is asking for six grand to supply and fit the panels, so about 3k for labour and cable. This seems like an easy DIY to save three grand. Is it? Am I missing something? We already have the conduit in place thorough the ridge into the loft for the PV cable. How do I connect the panels together? Do I just crimp a connector to a long cable and then connect the panles in series. The inverter is not going to be installed for a few months so the cable will be left in the loft for a while. I don't want to get electrocuted but I also want to save 3 grand on what looks like a days work. How hard is it to connect the panels and run the cable into the loft? Link to comment Share on other sites More sharing options...
TonyT Posted February 16 Share Posted February 16 (edited) The panels come with connectors on them, so you just need to link them up in series depending on the string voltage of the inverter. tje cable to the inverter will needs ends fitted, and then mounting isolators inverter, etc Edited February 16 by TonyT 1 Link to comment Share on other sites More sharing options...
JohnMo Posted February 16 Share Posted February 16 Starting at one end the first connection goes to the isolator via an extension. You then connect positive to negative along the string. The last panel will have a spare end, this end goes to the isolator, your isolator now has a positive and negative. Depending on panel voltage, you now a voltage that will kill you, so be careful. 1 Link to comment Share on other sites More sharing options...
Dillsue Posted February 16 Share Posted February 16 I'd take a step back and sort out your design and inverter before you start wiring. Youve got panels over 3 differing compass points so they will be generating at differing times. If you wire them all together they'll likely affect each others generation at differing times of the day and you'll not get the best out of them. You may also be over the inverters max input voltage. You'll likely want to wire them in 3 groups, one for each group facing the same direction. Each group will need its own MPPT input on the inverter. I'm not saying you should use a pro installer but the £6k quoted will likely include design and a warranty that things work, as well as installation. There's more to an install than the materials you've mentioned- inverter, isolators, meter, connectors, elec certification, DNO paperwork, crimper, connection to CU. Assuming you're grid tied, have you got DNO consent to connect a 12kw system. Hopefully your installer had included to sort that out?? Link to comment Share on other sites More sharing options...
Mr Blobby Posted February 16 Author Share Posted February 16 (edited) 4 hours ago, JohnMo said: Starting at one end the first connection goes to the isolator via an extension. What if we don't have an isolator yet? The place where the isolator and inverter is to be installed isn't built yet. We will just have a long cable from the panels on the roof. Maybe a temporary isolator in the loft? 2 hours ago, Dillsue said: I'd take a step back and sort out your design and inverter before you start wiring. Ah yes, I should have explained some more. The design is ok I think. Its the heights and electrocution that scare me a bit though. 😬 2 hours ago, Dillsue said: There's more to an install than the materials you've mentioned- inverter, isolators, meter, connectors, elec certification, DNO paperwork, crimper, connection to CU. The price quoted does not include the inverter. It is only to put the panels on the roof. That's why I hope there is some cost saving here, as long as I don't fall off the roof or get electrocuted. 2 hours ago, Dillsue said: Youve got panels over 3 differing compass points so they will be generating at differing times. You'll likely want to wire them in 3 groups, one for each group facing the same direction. Each group will need its own MPPT input on the inverter. The newer solis series 6 inverters have more than two trackers to support multiple roofs for far less cost than something like solar edge. It is interesting that no GB shops are selling these inverters yet and nobody, including my solar installer, had any knowledge about them. These inverters are easy to buy online from the EU. The G98 certificate appeared on the ENA database a few weeks ago so they should be ok, but our inverter isn't going to be installed for a few months so no rush. https://www.solisinverters.com/uk/energy_storage_inverters10/5_10k_s6_H_PRO_en.html 2 hours ago, Dillsue said: Assuming you're grid tied, have you got DNO consent to connect a 12kw system. Hopefully your installer had included to sort that out?? We have a 3 phase connection to the house so we are ok for a 10KW 3 phase hybrid inverter. Edited February 16 by Mr Blobby Link to comment Share on other sites More sharing options...
Dillsue Posted February 16 Share Posted February 16 Seems you've got a grip on the design, but.... You'll be aware that some of your strings could have 400+ volts on them once connected?? You seem a bit vague about hooking them up to isolators so you really need to to plan your final isolator positions and cable from the isolators out to the roof before you connect up the panels. If you do it the other way round you'll be handling live cables in the loft!! If you've got an electrician on site doing the house wiring maybe get him to give you a hand so you're clear on a safe method of hooking things up?? Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 17 Share Posted February 17 Hmm, good crimping is key as is correct handling of the live cables as is clambering about on your new metal roof. You also need the correct dc isolator and to divide the panels into strings correctly. Incorrect crimping is a fire risk and you’ve also got potential damage to your new roof too. Does the £6K include the inverter work etc? While I’m all for diy, maybe there’s a halfway house solution? Link to comment Share on other sites More sharing options...
Bramco Posted February 17 Share Posted February 17 10 hours ago, Mr Blobby said: The newer solis series 6 inverters have more than two trackers to support multiple roofs for far less cost than something like solar edge. It is interesting that no GB shops are selling these inverters yet and nobody, including my solar installer, had any knowledge about them. These inverters are easy to buy online from the EU. I see Solis inverters with multiple MPPT trackers on the ITS site -> https://www.itstechnologies.shop/search?q=solis but maybe they aren't series 6? Simon Link to comment Share on other sites More sharing options...
JohnMo Posted February 17 Share Posted February 17 10 hours ago, Mr Blobby said: What if we don't have an isolator yet? Buy one and do not connect until you do. 10 hours ago, Mr Blobby said: inverters have more than two trackers to support multiple roofs for far less cost than something like solar edge. You could do more than one inverter, two trackers inverter is easy to get and then add a second inverter. We have three arrays, done that way. Link to comment Share on other sites More sharing options...
Mr Blobby Posted February 18 Author Share Posted February 18 (edited) On 17/02/2024 at 08:10, JohnMo said: Buy one and do not connect until you do. This is kinda what I thought, so just intall a two-tracker DC isolator in the loft and then run the terminated cables from the isolator onto the roof. Connect the panels in series. In the future when the inverter is installed just run some wires from the isolater in the loft to the inverter. On a dark night I assume. I guess the DC cable should go in some steel conduit in the house. On 17/02/2024 at 07:58, Bramco said: I see Solis inverters with multiple MPPT trackers on the ITS site The only Solis inverters on that site with more than two trackers are the older version ones which are too big, from memory I think > 20KW. Even if we wanted to install an inverter that big, NIE won't allow it under G98. On 17/02/2024 at 08:10, JohnMo said: You could do more than one inverter I looked into this and while it is relatively straightforwad to put a single phase inverter on each phase to get more trackers, it is more expensive and more complicated with battery storage. The information I was getting from suppliers was thet three seperate single phase hybrid inverters will generate and discharge according to the load on each phase. To synchronise them is complex. The new 3-phase hybrid solis inverter is far simpler and far cheaper. The cynic inside me suspects they are not sold in the UK because there is more profit to be made from selling mulitple inverters or a solar edge system. Edited February 18 by Mr Blobby Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 18 Share Posted February 18 >>> The cynic inside me suspects they are not sold in the UK because there is more profit to be made from selling mulitple inverters or a solar edge system Possible but it could just be due to the very low numbers of domestic properties in the UK with 3P. Link to comment Share on other sites More sharing options...
Mr Blobby Posted February 26 Author Share Posted February 26 I asked the solar installer about DC isolators and he says they are a fire risk so he doesn't install them any more. Says the risk of shock from the DC cables is so low compared to AC (although admittedly fatal) that an isolator is not required. Which is interesting. After googling around it seems that the world maybe moving away from DC isolators. Link to comment Share on other sites More sharing options...
Bramco Posted February 26 Share Posted February 26 Interesting - I did wonder about putting one onto our system - especially as the inverter has a DC switch on the side - so a separate isolator was in my thinking overkill - but I went ahead and put one on as the installation manual had that as one of the steps. Simon Link to comment Share on other sites More sharing options...
Mr Blobby Posted February 26 Author Share Posted February 26 1 hour ago, Bramco said: Interesting - I did wonder about putting one onto our system - especially as the inverter has a DC switch on the side - so a separate isolator was in my thinking overkill - but I went ahead and put one on as the installation manual had that as one of the steps. Did you install anything else between the panels and the invertor? Or just the DC isolator? Link to comment Share on other sites More sharing options...
JohnMo Posted February 26 Share Posted February 26 1 hour ago, Mr Blobby said: I asked the solar installer about DC isolators and he says they are a fire risk so he doesn't install them any more. Says the risk of shock from the DC cables is so low compared to AC (although admittedly fatal) that an isolator is not required. Which is interesting. After googling around it seems that the world maybe moving away from DC isolators. New MCS Guide now explicitly states that an additional DC isolator is not required with inverters that already have integrated DC isolators - but to me the inverter is the only thing likely to fail, over time. The isolation switch on the inverter is fine, but does not allow to isolate the panels from the inverter, to then allow the inverter to be safely be replaced at some point in the future. So from a practical perspective I would always install one. Plus you can place it somewhere convenient, for yourself, electrician or fireman, rather than having to go into the loft etc. What fire risk is there in an isolation switch? That just sounds like he is making it up as he goes along. 1 Link to comment Share on other sites More sharing options...
Mr Blobby Posted February 26 Author Share Posted February 26 (edited) 9 minutes ago, JohnMo said: but does not allow to isolate the panels from the inverter, to then allow the inverter to be safely be replaced at some point in the future I think the installer's view is that when the inverter's isolator is in the open position then it's safe to disconnect the MC4 plugs on the string without any risk because the circuit is open. Not sure I'd want to do it though. 9 minutes ago, JohnMo said: What fire risk is there in an isolation switch? It has been known for isolaters to arc and catch fire (maybe in the open position?) so my installer's view is remove the isolator to remove the risk. Edited February 26 by Mr Blobby Link to comment Share on other sites More sharing options...
Dillsue Posted February 26 Share Posted February 26 23 minutes ago, Mr Blobby said: I think the installer's view is that when the inverter's isolator is in the open position then it's safe to disconnect the MC4 plugs on the string without any risk because the circuit is open. Not sure I'd want to do it though. It has been known for isolaters to arc and catch fire (maybe in the open position?) so my installer's view is remove the isolator to remove the risk. My understanding of things is you shut the inverter down before switching any isolator so there's unlikely to be any power flowing in the DC or AC side. Thats certainly the case with solaredge optimisers but maybe different with string inverters?? You'll not get any arcing if there's no power. Not sure how much arcing you'd get, if any, with a correctly rated DC isolator. Bit lax of the manufacturer if that was reasonably possible Link to comment Share on other sites More sharing options...
Bramco Posted February 26 Share Posted February 26 1 hour ago, Mr Blobby said: Did you install anything else between the panels and the invertor? Or just the DC isolator? Surge protection. Again, not sure this was necessary but... Simon Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 26 Share Posted February 26 (edited) >>> My understanding of things is you shut the inverter down before switching any isolator so there's unlikely to be any power flowing in the DC or AC side. That's sort of true i.e. no current will be flowing, but bear in mind that there will be the PV voltage (say, 400V DC) between the two plugs from the PV panels, so treat with caution. Edited February 26 by Alan Ambrose Link to comment Share on other sites More sharing options...
Mr Blobby Posted February 27 Author Share Posted February 27 Against my better judgemt I copped out and instructed the solar installer to put the panels on the roof. Scaffold is up. I'm supplying the S5 clamps. Panels cost retail: 3k. Installer supply and fit: 6k. Maybe a days work. No inverter. I haven't felt this ripped off since I paid my last solicitors' bill. Link to comment Share on other sites More sharing options...
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