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Thread: PV panels on target or above?

  1. #1
    balerman
    Guest

    PV panels on target or above?

    Ok guys now there are a lot of people with panels out there,how is it doing,assuming we all had prediction charts when installed.Mine are on target,15% above at the moment,and that is with a telegraph pole shading more than i thought,very pleased.

  2. #2
    big_phil
    Guest

    Re: PV panels on target or above?

    50 kw first day 250 kw !! ayrshire

  3. #3
    Exfarmer
    Guest

    Re: PV panels on target or above?

    First 6 months were over target but poor third quarter means I will be lucky to hit target but last few days are going well
    From sunny Suffolk

  4. #4
    mf6480
    Guest

    Re: PV panels on target or above?

    have people found them been affected much by the heat, i know people said the efficiency would drop when it was hot, got a 30kw system doing about 175 - 190 kw past few days. but does not peak as high.

  5. #5
    seedman stains
    Guest

    Re: PV panels on target or above?

    Coming to the end of the first years production,a little bit over estimation but not a lot.36kw system

  6. #6
    TC
    Guest

    Re: PV panels on target or above?

    Quote Originally Posted by mf6480 View Post
    have people found them been affected much by the heat, i know people said the efficiency would drop when it was hot, got a 30kw system doing about 175 - 190 kw past few days. but does not peak as high.
    I think i am finding that. I put 2.4KW on a shed by the house, it was peaking in march at 2.9kw this week it has not broken 2.
    Still on target to pay back in 5 years (free of income tax).

  7. #7
    mf6480
    Guest

    Re: PV panels on target or above?

    Quote Originally Posted by TC View Post
    I think i am finding that. I put 2.4KW on a shed by the house, it was peaking in march at 2.9kw this week it has not broken 2.
    Still on target to pay back in 5 years (free of income tax).

    Ours in march was hitting about 3% above rated, but in this heat they are about 15% down on rated. but still doing the kw hrs.

  8. #8
    NB
    Guest

    Re: PV panels on target or above?

    I would say mine are on target.(38.4 Kwp. on grainstore roof)
    I agree about the heat. I was producing more in March on a sunny day at 10am than a very hot sunny day in June at midday.

    I hope 21st June at midday GMT is cool and sunny then I will know what they can really do.

  9. #9
    farfrae
    Guest

    Re: PV panels on target or above?

    A few people are trying to deal with the efficiency drop off with temperature by making PV panels with Solar HW built into them (PVT Panels).

    They produce hot water as well as electricity and as a by product the thermal fluid cools the PV part of the panel. Thus in theory you could have electricity and hot water for the dairy or house from the same panels. I saw some at Ecobuild but they did look a tad 'Heath Robinsonish' but expect that the technologies will improve quickly.

  10. #10
    foxbox
    Guest

    Re: PV panels on target or above?

    Where is the heat generated then? Is it within the panel or behind it that causes the problem? For example will a ground mounted array have less of a problem than a roof mounted one as there won't be a roof sheet 6 inches behind it?

  11. #11
    Exfarmer
    Guest

    Re: PV panels on target or above?

    Any heat will affect the efficiency of any electrical apparatus
    I believe but stand to be corrected all electrical apparatus works best at absolute zero something like minus 270?

    I was concerned my pv is under performing, a 7.8system and am not sure if it is the heat or dust on the panels
    It is currently doing a max of 6.4 kv but it has peaked at 9.2kv but I am not sure when as I only get a daily reading if I go in my roof
    Last June we peaked at over 8kw

  12. #12
    kennyo
    Guest

    Re: PV panels on target or above?

    Quote Originally Posted by Lee View Post
    The average up to yesterday was 131.25 KWH per day. Our target average is 158.90 KWH per day so were about 18% off target at the moment. However we had a week of not producing anything in March during the really nice weather we had and then April in general was crap. Monitoring during april saw us at low as 85 KWH per day so I think had we not lost the week in March and April weather was 'more normal' I think we would be about on target. We've got 45 days left to take us to the full 12 months and daylight hours are now 16 hours so we'll see what happens.

    What I can say though that throughout last summer we were producing over 20% more than we expected on a daily basis.

    Swings and roundabouts.
    What size is you system Lee?

  13. #13
    Exfarmer
    Guest

    Re: PV panels on target or above?

    Have you cleaned your panels Lee?

  14. #14
    foxbox
    Guest

    Re: PV panels on target or above?

    Quote Originally Posted by Exfarmer View Post
    Any heat will affect the efficiency of any electrical apparatus
    I believe but stand to be corrected all electrical apparatus works best at absolute zero something like minus 270?

    I was concerned my pv is under performing, a 7.8system and am not sure if it is the heat or dust on the panels
    It is currently doing a max of 6.4 kv but it has peaked at 9.2kv but I am not sure when as I only get a daily reading if I go in my roof
    Last June we peaked at over 8kw
    I appreciate what you are saying but am surprised by the lack of answers from others on this. I know nothing about the construction of the panels but remember when Lee posted pictures of his roof mounted system he had odd panels left out to assist with ventilation. Presumably that means that a significant proportion of the heat can be removed by ventilation which may favour ground mounts from an efficiency point of view but with obvious security implications etc. However if this was the case would they not be mounted further from the roof sheets to aid ventilation further?

    Sorry if this seems like an inane question but we are just starting down the PV route and I am trying to get my head round the different elements of the systems. Further questions bothering me at the moment include how to assess the quality of a potential supplier, how easy is it to replace skylights if a system is built around them and after your post above how do we clean them if they are on a decent sized roof?! Any help with these greatly appreciated and sorry to the OP for going off topic

  15. #15
    Exfarmer
    Guest

    Re: PV panels on target or above?

    Obviously there are many different sizes and styles of installation
    The set up on my roof has a 6 inch gap under the panels and I would think that there is little to choose between this and ground mount for air flow as on a hot day I would imagine a fair draft would soon be created by convection under the panels
    I have just spoken to a window cleaner who claimed that he washed several sets of panels with his power washer (he was touting for business) and could reach about 40 feet (I am waiting for him to come and demonstrate hopefully on a sunny day and I may have before and after generating figures)
    Obviously roofs differ as do skylights
    Depending on size etc you may have to leave gaps to access to the lights
    Of course if it is grainstore may be best to ignore them. We took ours out when we started growing potatoes and did not miss them
    I used Evoenergy from Nottingham and found them very good on my 7.8 set up
    I would advise anyone to make sure you can read the inverters from ground level

  16. #16
    foxbox
    Guest

    Re: PV panels on target or above?

    Quote Originally Posted by Lee View Post
    Our gaps were left so they did not cover roof lights.

    Ventilation is not an issue on a roof thats 12 m above ground.
    Fair enough, how easy do you think it will be to change roof lights if one fails? Pheasants have a habit of breaking ours :cry: I suppose it would be easier to panel over them and replace with strip lights etc if it may be an issue though.

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