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Wow this has been really confusing read, disclosure - I'm in the solar industry... but I only do commercial installs (Our main client is Morrisons but also work for Asda, Tesco, Jaguar, Warburtons etc) so we know a little more than most, so Ive nothing to sell on the domestic level. But I'm quite willing to give advice as I hate all the small installers ripping people off as it gives the whole industry a bad name.
@SteveCritten as you say the important thing is the kWp size of the system, the number of panels is irrelevant. Efficiency is a bit of a misnomer in solar as all it refers to is the amount of light the panel can turn into electric from the area covered by the panels. Therefore if you've got a large roof you could use a lower efficiency panel but more of them e.g. 20 x 200w panels = 4000w (4kW) or 16 x 250w panels = 4000w or if using Sunpower panels 12 x 333w = 3999w.
The more efficient a panel is the smaller it needs to be to give an equivalent output so if you look at a typical 250w panel its 167cm x 99cm if you go for a very efficient module like Sunpowers Maxeon series then a 333w panel is about 150cm x 101cm. This smaller size means you can fit a larger system on a smaller roof. The only down size of this is that Sunpower know the value of their panels and they are nearly twice as much to buy than a standard panel (they are very good but you get what you pay for).
Whats important here is the size of the roof available, if you look at the cost of a system then about 50% of the cost is the panels and the rest is fixed costs - scaffold profit etc. The larger you make a system the only real additional cost is for more panel, so your overall cost per kW of panel installed is lower due to being able to spread the fixed costs over a larger system and thats the key. THE MOST IMPORTANT FIGURE IN A SOLAR SYSTEM IS THE COST PER KW OF PANEL INSTALLED or as we call it in the industry £/kWp.
Now thats not to say that cost is the way to buy a system as its not, the old adage YOU GET WHAT YOU PAY FOR is very true, as has been pointed out beware your warranties. Solar is a relatively new industry and a lot of the players in the market won't be around in a few years so stick to the biggest players in order to try and pick the long term winners for your warranties.
Panel Manufacturers I'd stick to Yingli Solar, Trina Solar, Canadian Solar, JA Solar, REC Solar, BENQ, Sunpower, SunEdison, LG, Panasonic (although these are expensive for what you get), Hyundai, Solarworld.
Inverter manufacturers, I'd stick to string inverters at the moment, the companies behind the micro inverters are still pretty young and the technologies are not very old although they undoubtedly will produce more power than string inverters over the system life time. Expect to pay £1000 to 1500 more for a micro inverter system than for a string inverter system. Manufacturers stick to European companies - SMA, ABB, Fronius, Schneider although I am looking at one Chinese company at the moment Huawei.
As has been said £5-7k for a 4kW system is about right but it will depend on things like how difficult the scaffold is, slate roof's cost more to do. That would be for a standard concrete tile roof with chinese panels and a string inverter. Expect upto £9k for Sunpower on a slate roof with a difficult scaffold say over a conservatory on a 3 storey building.
@emyace Eurosolar Ive never heard of but the data sheet for the panels lists Ulica as the manufacturer who are a Chinese maker of lower end panels, they are a 325w panel as they are a 72 cell panel - usual is 60 cell (thats a big panel 200cm x 100cm) its not a high efficiency panel its just got more cells in it. Cant say for sure but I'm not aware of them manufacturing in the UK (theres only about 6 or so in the UK)
If anybody wants any advice pls drop me an email at phil.roberts at gmienergy.co.uk |
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Author: gstyle
26-11-2019 03:54:34