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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorrevor
    • CommentTimeOct 18th 2017
    Does anyone have a view of whether solar edge is worth the extra expense? I have been quoted £7K for a 14 panel 4Kw system and do not know whether this is good value or not.
    • CommentAuthortony
    • CommentTimeOct 18th 2017
    Target price 4500
    • CommentTimeOct 18th 2017
    I paid significantly less for a 4 kW Enphase system over two years ago, so it sounds expensive to me. Get more quotes.
    • CommentAuthorrevor
    • CommentTimeOct 19th 2017
    Looks like from your comments overpriced will be getting more quotes.
    Following for advice.

    Are these prices fitted?
    • CommentAuthorSteveZ
    • CommentTimeOct 19th 2017
    I have had a Solar Edge system since 2012 and I am very pleased with it. The new series inverter is lighter in both weight and power demand, and is compatible with the Tesla Powerwall if you want to add battery storage later.

    Solar Edge provide a website to monitor your panels individually, so spotting a problem with a single panel is simple.

    The main advantage I see is the use of each individual panel output, rather than running the array at the lowest output as in a normal string arrangement. In my case this can be up to 30W best to worst panel. If you have any hint of a shading problem, avoid a normal string system

    The inverter carries a 12 year warranty and the boxes on the roof 25 years.

    Having said all that, your quote seems a bit high, although it might be influenced by the actual panels themselves. If you are in the Southwest, try Sungift in Exeter. Get more quotes and check their customer feedback - it makes a big difference if you get a good installation company!!

    Usual disclaimer - just a satisfied customer

    I hope this helps
    If your existing inverter is still OK, rather then going for a new Solar Edge inverter and optimsers, why not try
    Tigo TS-4R-O Panel Optimisers. They work with your existing inverter.

    We had a 1.8kw extension to our existing 4kw array and had these added to the panels due to a bit of a shading problem. It's only been fitted for a short while, so I have no figures to report back.
    I have a Solar Edge system and the price I was quoted didn't differ too much from the one you've had. (I'm in London.)

    I have nothing to compare it against, but am happy with the system and echo many of the points made by SteveZ:
    - Customer services have been good when I've spoken to them
    - Having individual panel monitoring is useful (your inverter needs to be connected to the internet for this to happen, I think the newer models have wifi).
    - I see big variations in generation by panel due to shading and I think the individual optimisers are a big benefit in this case
    • CommentTimeOct 19th 2017
    Personally I prefer the Enphase system of microinverters behind the panels, so there is no DC cabling at all and no inverter. The feed down from the roof is a normal armoured mains cable, which isn't live unless mains is applied to it. There is a small gateway device that uploads the generation data to their website. Everything has a 25 year warranty as standard.
    • CommentAuthorSteveZ
    • CommentTimeOct 19th 2017
    I discounted a string inverter system because I have a split system on two roofs and some shading issues. If you don't have these problems, maybe a straightforward string system would be fine for you.

    I had the discussion with myself about micro-inverters vs MPPT boxes plus simple inverter way back. Both are better with shading issues than the conventional string inverters, because they do the power point tracking at each panel.

    The micro-inverters have the advantage of doing all the work on the roof and feeding AC power into the house using a conventional mains cable. They are more complex than the simple MPPT box of the Solar Edge system and are more prone to failure simply because there are more components to go wrong. In fact, I believe the model I was considering has gone out of business due to the failure rate. Fortunately, they could not deliver in time, so I went for the Solar Edge - close call there!

    The Solar Edge does feed DC down from the roof, although the inherent dangers, to say firemen, are mitigated by the automatic panel output reduction to 1 volt per panel when the isolating switch is OFF. I don't know if string inverter systems still produce power in sunshine when switched off at the inverter in case of a fire.

    Both systems will be more difficult and therefore expensive to repair than a string inverter system, as access to the panels on the roof (assuming the system is roof mounted, of course) will be required. These days that means scaffolding etc!
    • CommentAuthorjamesingram
    • CommentTimeOct 20th 2017 edited
    solar edge shouldn't be significantly higher than a standard system , additional cost is just the optimisers at about £50 each. £4-5k is the going rate.
    i fitted a few systems and have one of my own arrays on solaredge kit. I like them , simple and safe as it drops the output to 1 Vdc per panel if any error occurs.
    That said I've had one optimiser fail recently after 2 years, fortunately it was an easy accessible panel to swap it out
    • CommentAuthorJeff B
    • CommentTimeOct 20th 2017
    I would urge caution if any system you are looking at requires use of an external website to monitor your microinverters. If the company fails, you will not be able to monitor them. This is what happened to me with Enecsys microinverters. Fortunately I found a guy in the USA who was able to supply a stand-alone gateway which plugs directly into my PC so I can monitor the outputs locally.
    • CommentTimeOct 21st 2017
    Posted By: Jeff BI would urge caution if any system you are looking at requires use of an external website to monitor your microinverters. If the company fails, you will not be able to monitor them.

    Yes, I worried about that and about the possible security risks of external network connections. But the Enphase protocol has been hacked so if necessary I could intercept it and process the data myself. I expect though that there would be some alternative arrangements made if necessary, by the community or by authority.

    A normal inverter gives you no information about individual panels at all though, so that's not a difficult target to improve on.
    Am I Being silly but are these prices installed? What do they include? I'm new to Solar Power but having a South facing roof and ASHP with hot water tank could be the next investment.

    What sort of payback do they have and are the FIT's any good/worth the bother?
    • CommentAuthortony
    • CommentTimeOct 23rd 2017
    Yes, installed prices, FiTs are a must and help, returns are low, 3 to 5% with very high daytime use may be 6%
    • CommentAuthorrevor
    • CommentTimeOct 23rd 2017
    Looking a bit more into this the does one really need the extra expense of the edge upgrade if all the panels are in the same alignment not shaded etc and on the ground so easy to check and maintain. Also don't like the idea of someone else being able to remotely monitor my system and will that cost me an annual fee?
    Answering a few of the points above:
    1. No shading - I didn't think my roof would experience any shading, but from the monitoring I can see that one panel is being shaded against my initial expectations, so having the optimisers is a benefit in my case. If the panels are on the ground I would have thought the risk of shading is higher (as they are less likely to be raised above obstructions).

    2. There is no annual fee for the SolarEdge portal. Yes, it is true in theory someone else could see your generation stats, but it isn't a material concern for me (there are other parts of my digital life I'd worry about more).

    3. You don't need to have only the SolarEdge monitoring. The system will more than likely come with an in house monitor as well (which will probably be for the whole system only).
    That price sounds high unless you have eg scaffolding on a London street or live in a lighthouse.

    I put a 10kWp Solar Edge system in in Jan 2016 on 3 aspects, and it came to 11,800 installed, and they gave me a couple of spare panels and solar edge devices, with Black Panels. All FiT connected etc.

    Aim for £1250 per kWp all in imo, and aim to undercut that a little more.

    Does anyone have a very recent quote post the Brexit fall in the £, as that may have had an impact.
    • CommentAuthorrevor
    • CommentTimeOct 26th 2017
    My system would be on the ground and I have had another quote 6250 inc vat but not edge and was recommended a 5kw array (18 panels) with 3.6 kw inverter as this would give a flatter performance curve and a greater total output over the day. Does this make sense?
    • CommentTimeOct 26th 2017
    Inverter seems too small, usually 10% undersize.
    • CommentAuthorjamesingram
    • CommentTimeOct 27th 2017 edited
    not sure how undersizing that much improves overall output.
    every time your panels produce more than 3.6kW the inverter will clip it at that level losing all that potential generation.
    sound to me they just want to get round doing a G59 preregistration to the DNO
    some info on the subject
    • CommentTimeOct 27th 2017
    I would think that the inverter's life may well be shortened too, that is a low of power to dissipate on a sunny day.
    • CommentAuthorgoodevans
    • CommentTimeOct 28th 2017 edited
    I'm not sure the inverter ends up getting hotter - I think it's the solar panels - but the extra heat won't do them any favours either. (But I could be wrong on either point)
    • CommentAuthorMikC
    • CommentTimeOct 28th 2017
    Most solar regulators limit output by shorting the panels rather than dissipating the energy through a heat sink, so the panels get hot, but it's not usually a problem . I would assume that inverters do this also but I like to know from anyone more knowledgeable.
    Posted By: revorMy system would be on the ground and I have had another quote 6250 inc vat but not edge and was recommended a 5kw array (18 panels) with 3.6 kw inverter as this would give a flatter performance curve and a greater total output over the day. Does this make sense?

    My understanding is that the inverter limits the power to the grid to stay within allowed limits. The 5kw (max) array is sized to give higher output on marginal days so that the overall production is up but the system never exceeds the allowed limit. Am I correct in this understanding?
    yes that appears the case , but you can quite easily go above that 3.6kW limit by doing the correct paperwork (usually at a cost) as mentioned.
    sticking 5kW of panels on a 3.6kW inverter is a poor design if you're interested in maximising generation
    anyone interested have a play with this and it'll show you some example of inverter to panel sizing and the resulting efficiencies
    • CommentAuthorjamesingram
    • CommentTimeOct 28th 2017 edited
    revor , the only way your spec might make some sense if it was 2 string of 9 facing east/west at a low angle of inclination perhaps,
    still seems odd.
    • CommentTimeOct 28th 2017 edited
    I once fitted 3.5 kWp to a 3 kW SunnyBoy and the fan was blowing a lot of hot air out.
    I think it is the inverter that regulates the power output not any shorting of panels (though that may happen to an extent).

    The limit is 16 Amp a phase usually, the kW is dependant on the local grid voltage.

    This Australian site (providence unknown) suggests that 30% under-sizing is possible, which suggest that a 3.8 kW inverter is optimal.
    • CommentAuthorskyewright
    • CommentTimeOct 28th 2017
    AIUI, larger scale oversizing is much more common nowadays because:

    a) Panels are cheaper.
    b) There is no longer a drop in FIT rate if the panels exceed 4kWp (IIRC the first significant rate threshold is up at 10kWp or so? More than you could fit on most roofs)..
    c) There are more inverters & systems that have been designed to handle this situation.
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