Jeremy Harris Posted September 9, 2019 Share Posted September 9, 2019 18 minutes ago, Bitpipe said: Could you not do it with a cherry picker? Good question. I guess it depends on whether a cherry picker would be considered as being a safe way of working on a roof. It could be that access for a cherry picker might be difficult in some cases. I wonder how far a cherry picker can reach out laterally? Link to comment Share on other sites More sharing options...
Bitpipe Posted September 9, 2019 Share Posted September 9, 2019 14 minutes ago, JSHarris said: Good question. I guess it depends on whether a cherry picker would be considered as being a safe way of working on a roof. It could be that access for a cherry picker might be difficult in some cases. I wonder how far a cherry picker can reach out laterally? Roofers often just work off ladders but guess the issue is manipulating a large panel safely. Link to comment Share on other sites More sharing options...
Alexphd1 Posted September 9, 2019 Share Posted September 9, 2019 (edited) Every site is different for access, our site you would need a telehandler with a cage but would wreck the garden. There's no way I would be happy working with PV panels on our roof 45 degrees @ 8m above ground level with just ladders. I was trying to stress try and way up all pros and cons and if you can simply stuff just now all the better. I was 50/50 with micro v single inverter but ended up with a free SMA one so that swung that. We located the inverter in the garage the downside being we had longer DC cable run that we would have liked but it's not the end of the world. I didnt know you could check status on individual micro inverters this is a big plus point for maintenance at a later date. Edited September 9, 2019 by Alexphd1 Link to comment Share on other sites More sharing options...
SteamyTea Posted September 9, 2019 Share Posted September 9, 2019 56 minutes ago, Andrew said: Is there any practical limit on how far the DC from the panels can be run? Not really. It is more efficiency to run DC over longer distance for any given cable size. So just a matter of doing the sums. There was a guy, from the other place, that lives near to me. He had a ground mounted array that ran DC a good 50 metres on the standard 4mm2 cable. It worked fine. Link to comment Share on other sites More sharing options...
billt Posted September 9, 2019 Share Posted September 9, 2019 57 minutes ago, Andrew said: Not especially, there is a neighbour's tree which will cause some minor shading at times. Main preference for micro-inverters was due to our panels being split over different sections of the main house roof and the detached garage. There seems to be an interesting debate regarding the benefits of micro-inverters vs normal inverter, the maintenance argument being quite persuasive. Is there any practical limit on how far the DC from the panels can be run? I guess we could have two 'normal' inverters, one in the house and the other in the garage. I'd need to have a look at how the cost stacks up too. Another option if shading is an issue is optimisers. SMA/Tigo TS4-O are available for about £45 each. You need one per panel but only for the shading affected ones. There's no particular limit to DC cable length; depends on the string voltage and cable size. I had about 30M runs on the old ground mounted system and the losses were negligible. SMA has a wonderful free, online, system design tool which will calculate the cable losses for you, among lots of other things. https://www.sunnydesignweb.com/ Link to comment Share on other sites More sharing options...
Gone West Posted September 10, 2019 Share Posted September 10, 2019 11 hours ago, Andrew said: I guess we could have two 'normal' inverters, one in the house and the other in the garage. I'd need to have a look at how the cost stacks up too. I don't think you would want an inverter inside the house. It produces most electricity and therefore heat in the summer when the weather is hot. Adding more heat to the inside of the house in the summer isn't a good idea. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 10, 2019 Share Posted September 10, 2019 3 minutes ago, PeterStarck said: I don't think you would want an inverter inside the house. It produces most electricity and therefore heat in the summer when the weather is hot. Adding more heat to the inside of the house in the summer isn't a good idea. Noisy too. Fitted a 3 kW SMA to a 3.5 kW array. When it was at full chat, the cooling fan was very load and 500W was coming out as thermal energy. It was fitted (against my advice) in a spare bedroom. If possible, stick the inverter on the coldest side of the house. Link to comment Share on other sites More sharing options...
andyscotland Posted September 10, 2019 Share Posted September 10, 2019 11 hours ago, JSHarris said: Good question. I guess it depends on whether a cherry picker would be considered as being a safe way of working on a roof. It could be that access for a cherry picker might be difficult in some cases. I wonder how far a cherry picker can reach out laterally? "Normal" size ones are about 6-7m as I recall, though you can get larger. The major issue with using one to work on a roof or above a surface though is it's really awkward to work at the bottom of the basket because the floor, kick rail, guard rails get in the way. So you might be able to get the bottom of the basket against the roof surface, but not be able to do much when you get there. They're good for working on a vertical surface or underneath a ceiling. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 10, 2019 Share Posted September 10, 2019 17 minutes ago, SteamyTea said: Noisy too. Fitted a 3 kW SMA to a 3.5 kW array. When it was at full chat, the cooling fan was very load and 500W was coming out as thermal energy. It was fitted (against my advice) in a spare bedroom. If possible, stick the inverter on the coldest side of the house. Our 6 kW inverter doesn't have any cooling fans, just a big heatsink on the front. It makes a very slight hum when operating near full power, but you need to be close to it to hear this, and most of the time it's completely silent. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted September 10, 2019 Share Posted September 10, 2019 27 minutes ago, PeterStarck said: I don't think you would want an inverter inside the house. It produces most electricity and therefore heat in the summer when the weather is hot. Adding more heat to the inside of the house in the summer isn't a good idea. Where do you have yours, or are you running on micro inverters? Link to comment Share on other sites More sharing options...
Gone West Posted September 10, 2019 Share Posted September 10, 2019 Just now, MikeSharp01 said: Where do you have yours, or are you running on micro inverters? If we fit a system, I'm still thinking about whether it's worth it, it will be using Enphase IQ7 micro-inverters. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted September 10, 2019 Share Posted September 10, 2019 On another wrinkle - I have been looking at these in roof systems but I am struggling to get the panels flush with our fibre cement (Thrutone) tiles, this is similar to the problems I am having getting a water tight design for the roof windows flush with the tiles. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted September 10, 2019 Share Posted September 10, 2019 1 minute ago, PeterStarck said: If we fit a system, I'm still thinking about whether it's worth it, it will be using Enphase IQ7 micro-inverters. Yes - sorry Peter - I was only there last week and we talked about the possible array, should have remembered. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 10, 2019 Share Posted September 10, 2019 1 minute ago, MikeSharp01 said: On another wrinkle - I have been looking at these in roof systems but I am struggling to get the panels flush with our fibre cement (Thrutone) tiles, this is similar to the problems I am having getting a water tight design for the roof windows flush with the tiles. Our panels are proud of the slates by a fair bit, but it doesn't really stand out when looking from the ground. At a guess I'd say the panels may be around 30mm to 40mm higher than the slates: Link to comment Share on other sites More sharing options...
Bitpipe Posted September 10, 2019 Share Posted September 10, 2019 We used micro inverters and I agree that maintenance may be an issue (and something I gave no consideration to), although our roof design is a bit more forgiving as it has a GRP ledge at the base and a sizeable flat area at the front. As we have slates, the trays are flush with those but the panels do sit proud, however all is watertight so not sure whether that's a function of the panel or tray. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 10, 2019 Share Posted September 10, 2019 1 minute ago, JSHarris said: Our panels are proud of the slates by a fair bit, but it doesn't really stand out when looking from the ground When I first came around I never noticed your modules. May have been different if the roof had red tiles on it, but then, that is a Norfolk thing. Link to comment Share on other sites More sharing options...
dpmiller Posted September 10, 2019 Share Posted September 10, 2019 We've microinverters and I chose to hang them in the loft. Any loss of life is easily compensated for by ease of replacement. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 11, 2019 Share Posted September 11, 2019 15 hours ago, dpmiller said: We've microinverters and I chose to hang them in the loft I think you are not allowed to put inverters in a loft anymore. This may just be for normal ones. Amy be worth someone checking up in the latest edition of the electrical standards. Link to comment Share on other sites More sharing options...
dpmiller Posted September 11, 2019 Share Posted September 11, 2019 nothing that I can see in the 17th? And if it's a non electrical reg I'd be intrigued considering the number of gas boilers that are fitted in loftspaces these days... Link to comment Share on other sites More sharing options...
SteamyTea Posted September 11, 2019 Share Posted September 11, 2019 5 minutes ago, dpmiller said: nothing that I can see in the 17th? And if it's a non electrical reg I'd be intrigued considering the number of gas boilers that are fitted in loftspaces these days... I seem to remember that it was something that came in a few years back It may be an MCS thing. Does the 17th say anything about suitable positions. Wording like that is often a catch all. But all the same, I am not sure that putting an inverter in potentially 60° C is a good idea. Link to comment Share on other sites More sharing options...
dpmiller Posted September 11, 2019 Share Posted September 11, 2019 think it's much cooler under a panel outside? Link to comment Share on other sites More sharing options...
SteamyTea Posted September 11, 2019 Share Posted September 11, 2019 Just now, dpmiller said: think it's much cooler under a panel outside? I have often wonders that. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 11, 2019 Share Posted September 11, 2019 Nothing in the 18th Ed AFAICS from a quick scan, either. Not sure that this would be something that would get into BS7671 though. Link to comment Share on other sites More sharing options...
dpmiller Posted September 11, 2019 Share Posted September 11, 2019 Just now, SteamyTea said: I have often wonders that. me too. there's around the same gap between the back of our (black) tiles as the under-felt ventilation gap. Dunno. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 11, 2019 Share Posted September 11, 2019 16 minutes ago, dpmiller said: me too. there's around the same gap between the back of our (black) tiles as the under-felt ventilation gap. Dunno. There will be about 20% less energy because the modules take that away. There is also convection currents, which says to me that microinverters should be positioned at the bottom of the module. The fact that inverters are very reliable, implies that temperature is not a huge problem. Link to comment Share on other sites More sharing options...
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