Triassic Posted February 21, 2019 Share Posted February 21, 2019 I'm installing 4kw of solar PV. As we're in a National Park and the planner asked for an in roof installation. This is what I asked of the supplier - "I'm looking to install a 4Kw solar PV system. As we are in a National Park, so all black panels and an in-roof mounting kit has been specified. The panels will be split 50:50 over a south and a west facing roof. There is some slight leaf shading from some adjacent trees." This is what they suggest - We could supply the following IN-ROOF 3kWp Solar PV Kit systems; Solar PV Kit Options 14 x Canadian Solar Mono 280W (All Black) solar panels 1 x Solis 4.0kW Dual tracker inverter 1 x GSE Integration in-roof mounting kit (2 rows of 3 in portrait and 2 rows of 4 in portrait) 1 x All cables, clips, generation meter, AC/DC isolators Is this the right kit for the job, will the inverter handle the shading. Any other comments? 1 Link to comment Share on other sites More sharing options...
Ferdinand Posted February 21, 2019 Share Posted February 21, 2019 (edited) 27 minutes ago, Triassic said: I'm installing 4kw of solar PV. As we're in a National Park and the planner asked for an in roof installation. This is what I asked of the supplier - "I'm looking to install a 4Kw solar PV system. As we are in a National Park, so all black panels and an in-roof mounting kit has been specified. The panels will be split 50:50 over a south and a west facing roof. There is some slight leaf shading from some adjacent trees." This is what they suggest - We could supply the following IN-ROOF 3kWp Solar PV Kit systems; Solar PV Kit Options 14 x Canadian Solar Mono 280W (All Black) solar panels 1 x Solis 4.0kW Dual tracker inverter 1 x GSE Integration in-roof mounting kit (2 rows of 3 in portrait and 2 rows of 4 in portrait) 1 x All cables, clips, generation meter, AC/DC isolators Is this the right kit for the job, will the inverter handle the shading. Any other comments? I think one thing at issue is whether your ‘slight’ is enough to justify individual panel optimisation ie solaredge or micro inverters, or not. This kit does not seem to include such. And I think that needs more information to assess. It will be 10-20 per panel or so ... or that is what it was for me. Ferdinand Edited February 21, 2019 by Ferdinand Link to comment Share on other sites More sharing options...
ProDave Posted February 21, 2019 Share Posted February 21, 2019 I presume quoting for less than 4KW is because one of the roofs won't fit enough panels? How bad is the shading? Whole roof? one panel? Link to comment Share on other sites More sharing options...
Ferdinand Posted February 21, 2019 Share Posted February 21, 2019 1 minute ago, ProDave said: I presume quoting for less than 4KW is because one of the roofs won't fit enough panels? How bad is the shading? Whole roof? one panel? 14 x 280 = 3.92. Link to comment Share on other sites More sharing options...
ProDave Posted February 21, 2019 Share Posted February 21, 2019 16 minutes ago, Ferdinand said: 14 x 280 = 3.92. So why did the supplier describe it as 3KWp? Link to comment Share on other sites More sharing options...
Ferdinand Posted February 21, 2019 Share Posted February 21, 2019 56 minutes ago, ProDave said: So why did the supplier describe it as 3KWp? I have no idea ... Link to comment Share on other sites More sharing options...
NSS Posted February 21, 2019 Share Posted February 21, 2019 We have 14 x 280 panels split over 3 roof areas (east, south and west) and also suffer some slight shading. We have SolarEdge inverter and it is noticeable how some panels on the part-shaded sections perform far better than others. If we had not gone for SE then I estimate energy generation could be down by as much as 10% on some days. 2 Link to comment Share on other sites More sharing options...
Triassic Posted February 21, 2019 Author Share Posted February 21, 2019 I asked for 4kw, I pointed out that a couple of panels in each string will be partially shaded. I have plenty of roof area available, but lower down the roof so potentially partially shaded. Link to comment Share on other sites More sharing options...
sam Posted February 21, 2019 Share Posted February 21, 2019 I've just been doing calculations on this. I have been quoted an extra £700 for Solar Edge vs Solis. In order to get the same financial return (IRR) I would need more than 15% additional output on average, and to be able to use this extra myself (in addition to higher FIT/export). On this basis I am planning to stick with the cheaper Solis. I'm planning to install 11x 320W REC N-peak mono panels, all on an unshaded WSW roof. Link to comment Share on other sites More sharing options...
PeterW Posted February 21, 2019 Share Posted February 21, 2019 @sam is this MCS..?? If so, ask them to price micro inverters instead as they work out cheaper usually. You can also be clever and you don't need to pair up adjacent panels with dual feed micro inverters so you can spread the shading effect. Link to comment Share on other sites More sharing options...
sam Posted February 21, 2019 Share Posted February 21, 2019 @PeterW This is MCS - I should just be able to get in before the FIT ends! On an unshaded roof, do you have any idea how much extra output I might get from microinverters rather than the single inverter? Can you explain the pairing up idea; I've heard this before but don't understand why it doesn't have the same negative impact as putting many panels though a single inverter (although obviously less so as only 2 panels)? Link to comment Share on other sites More sharing options...
PeterW Posted February 21, 2019 Share Posted February 21, 2019 Micro Inverters allow you to convert the output from a single panel. If they are in different levels of shade, the micro inverter itself regulates just the panel it is connected to. Dual input inverters take two panels but potentially limit to the lowest output panel - If you know how your shadows fall across the roof from fixed structures, it can sometimes benefit from staggering the panels so you lose less output. I would go with micro inverters any time as you don't need optimisers etc and routing the power becomes one of a lower current AC voltage rather than a higher current DC. 1 Link to comment Share on other sites More sharing options...
scottishjohn Posted February 21, 2019 Share Posted February 21, 2019 so to clarify for me --NON pv man -- if you have panels with dif outputs it will level them out at average of all or drop output to what lowest one is out putting Link to comment Share on other sites More sharing options...
Ed Davies Posted February 21, 2019 Share Posted February 21, 2019 For a single string of panels you'll get the sum of the voltages of the panels but, more or less, the lowest of the currents (OK, maybe a little bit more but not much). Sadly, the main effect of shading a panel is to reduce its current, the voltage only decreases a small amount. So, if one panel is shaded to reduce its current to half the full sun value then the whole string will produce half the current so half the power. Link to comment Share on other sites More sharing options...
Triassic Posted March 30, 2019 Author Share Posted March 30, 2019 300W / 305W JA All Black Solar Panel - Mono Percium - Latest Tech - MCS Approved. £123 each. Is this s reasonable price? Link to comment Share on other sites More sharing options...
PeterW Posted March 30, 2019 Share Posted March 30, 2019 44 minutes ago, Triassic said: 300W / 305W JA All Black Solar Panel - Mono Percium - Latest Tech - MCS Approved. £123 each. Is this s reasonable price? JA 305W Mono £0.293p pW (£89.50 per module) From Wagner Renewables this week. 1 Link to comment Share on other sites More sharing options...
Triassic Posted March 31, 2019 Author Share Posted March 31, 2019 On 30/03/2019 at 08:21, PeterW said: JA 305W Mono £0.293p pW (£89.50 per module) From Wagner Renewables this week. Just emailed them to confirm the price, I do like a bargain! 1 Link to comment Share on other sites More sharing options...
ProDave Posted March 31, 2019 Share Posted March 31, 2019 15 minutes ago, Triassic said: Just emailed them to confirm the price, I do like a bargain! That to me seems what SHOULD be the normal price now to make it viable without any FIT. I am sure some of the MCS installers are hanging on to the higher prices in a forlorn hope. Link to comment Share on other sites More sharing options...
K78 Posted March 31, 2019 Share Posted March 31, 2019 I know I’m in the vast minority. But it I don’t plan to have any PV. Living in the north west and without FIT I see little point. Am I missing something? Link to comment Share on other sites More sharing options...
ProDave Posted March 31, 2019 Share Posted March 31, 2019 17 minutes ago, K78 said: I know I’m in the vast minority. But it I don’t plan to have any PV. Living in the north west and without FIT I see little point. Am I missing something? There is something nice about having some of your energy use generated by free renewable means. But without any FIT to subsidise it, it has to be cost effective. Here in the Highlands, I am expecting my system to have repaid it's capital cost in about 6 years. Any longer than that and it's viability is in serious question. Once the capital outlay has been repaid it is free electricity for as long as the panels last, accepting you might have to replace the inverter if it fails. 1 Link to comment Share on other sites More sharing options...
Triassic Posted April 1, 2019 Author Share Posted April 1, 2019 On 30/03/2019 at 08:21, PeterW said: JA 305W Mono £0.293p pW (£89.50 per module) From Wagner Renewables this week. I emailed with my lis5 of panel and equipment requirements and strangely I’ve not had a reply, maybe I’ll have to phone them tomorrow Link to comment Share on other sites More sharing options...
PeterW Posted April 1, 2019 Share Posted April 1, 2019 Normally pretty good - pick the phone up to them and they are responsive. Link to comment Share on other sites More sharing options...
Triassic Posted April 2, 2019 Author Share Posted April 2, 2019 Right, I've talked to Darren at Wagner and my options are 13 panels, giving a total of 3.956Kw. I don't like odd numbers. If I get an inverter that limits output to the grid, could I get 14 panels? If I go for 12 panels that gives an output of 3.6Kw. Link to comment Share on other sites More sharing options...
ProDave Posted April 2, 2019 Share Posted April 2, 2019 What matters to the DNO is the maximum output of the inverter. So 14 panels connected to a 3.68KW inverter would be fine and a lot of the time would give more output than 12 panels would. Just make sure the max voltage is within the limit for the inverter when using 7 panels per string. Link to comment Share on other sites More sharing options...
Triassic Posted April 2, 2019 Author Share Posted April 2, 2019 6 hours ago, ProDave said: Just make sure the max voltage is within the limit for the inverter when using 7 panels per string. The panels will be split 6 on one roof and 8 on the other. Im thinking I’ll put the 8 on the south facing Roof and the 6 on the west facing roof. Link to comment Share on other sites More sharing options...
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