4KW system running at 3KW

• • #16645 Reply
    
    Mick

    Guest

    Hi, can someone explain this. Just had a 4KW PV system installed on a south/east roof. I’ve had sunshine and clear skies all day today as the sun has moved around the panels. No shading issues, all the panels are in clear view of the sun. The biggest generation was 3.2KW (i’ve got a geo monitor, but I also checked the Solax inverter display too). Why does a 4kW system not peak at 4KW in clear sunshine and blue skies. I read somewhere that a loss of up to 25% would be expected on a hot day in the summer (bringing a 4kW system down to 3KW) although today is a March day. Is 3.2KW (although it was averaging around 2.9KW) what I can expect from my 4KW system? Thanks, Mick

  • #16646 Reply
    
    Stuart

    Guest

    Hi Mick

    I think this will answer your query:

    Breakdown of annual yield:

    Jan – 2.9%
    Feb – 5.2%
    Mar – 7.7%
    Apr – 10.8%
    May – 13.2%
    Jun – 14.0%
    Jul – 13.5%
    Aug – 11.6%
    Sep – 9.0%
    Oct – 6.2%
    Nov – 3.6%
    Dec – 2.4%

    The sun is still low down in the sky, so I would expect your output figures to increase over the next couple of months. If they don’t, then have a word with your installer.

    Hope this helps.

    Stuart

  • #16680 Reply
    
    Jamie Clarke – Firehawk

    Guest

    Hi Mick. A 4kw system doesn’t produce 4kw. It simply means that you have 4kw worth of solar panels in your system. As part of the design process your supplier should have provided you with a generation forecast using your Irradiation Value. This depends on your location in the UK, the inclination / pitch of your roof and the orientation from the south. This value, will tell you how many watts you will generate per kilowatt installed. Every system is subject to a efficiency loss due to orientation / inclination unfortunately.

    Of course using high quality products will have great effect on your production, especially over a longer period.

    If you know your postcode, orientation and inclination I can give you a forecast and tell you how much production you should expect.

  • #16803 Reply
    
    Gerald Brady

    Guest

    Hello Mick,

    I suspect your low reading was due mostly to the angle of the sun on your panels. If your roof angle is shallow or your roof is a long way from due south then you wouldn’t get that close to the maximum. It is now almost mid summer. Has your reading improved. My system is a 3.84 kw system and it regularly reads 4 kw in April and September when the weather isn’t particularly hot and the sun is at about 90 degrees to my panels (My roof is 55 degrees from the horizontal)

    The

  • #16804 Reply
    
    Gerald Brady

    Guest

    Hello Mick,

    I suspect your low reading was due mostly to the angle of the sun on your panels. If your roof angle is shallow or your roof is a long way from due south then you wouldn’t get that close to the maximum. It is now almost mid summer. Has your reading improved? My system is a 3.84 kw system and it regularly reads 4 kw in April and September when the weather isn’t particularly hot and the sun is at about 90 degrees to my panels (My roof is 55 degrees from the horizontal)

  • #16858 Reply
    
    Roger

    Guest

    Hi I have a similar issue, my 3.75Kw system installed last year often reads 3.72Kw on the geo when the sun is on it, however, today 30/6 (btw hottest day of the year so far 30C)in full sun, directly onto the panels, roof pitch 45degrees, is disappointingly only showing 2.88Kw, is it the heat increasing resistance?

  • #16899 Reply
    
    Roger

    Guest

    Update, DUST! layer of Saharah dust on panels, had a thunderstorm last night and hey presto panels back to maximum