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Discuss How much power would you expect to be produced in Feb? in the Solar PV Forum area at

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  1. richlatham

    richlatham Guest

    I had a 3.36Kw solar system installed a few days ago.
    Today was a sunny day and the system generated 7.35 kWh.

    We are in the East Midlands, face ESE and the roof angle is 30 degrees, no shading.

    Is 7.35 about what we would expect?

    Are there any tables that show what you might expect on sunny days throughout the year - I know the SAP calculation gives aproximate expectations for the year, but I would be interested in a breakdown by time of year.
  2. i=p/u

    i=p/u Electrician's Arms

    well the tv is on disney most days the kettle every morning washing machine everyday so about£60 /£0.17= about 360 kw
  3. madmurg

    madmurg Guest

    try this page PV potential estimation utility
  4. richlatham

    richlatham Guest

    Thanks - I think I understand what it says.:hair:
  5. FB.

    FB. Electrician's Arms

    If the scaffolding is still up, there could be shading on the panels - a long, thin shadow diagonally across can virtually shut down a panel, as none of its rows of cells can complete a circuit (due to shaded cells) and bypass diodes will not be much help if there are diagonal shadows from scaffolding across several panels at once.

    Having said that, 7.35kW is definitely more than you'd expect on an average February day. 4kWh per day total generation would sound like a reasonable February daily average for your system.
    However, the amount of direct sunshine on the panels is the main factor; your system will work probably hit its maximum potential between about 9am and 11am, reaching about two-thirds of maximum summer potential (about 2.2kW per hour in your case) - assuming the sun is out.
    In the afternoons your generation rate will be a mere trickle in comparison to mid-morning.
    Cloudy days generate about half the average, while sunny days will double or triple the average expected daily output figure.

    Regarding the PV estimation utility linked by an earlier poster: I think that using the PVGIS-CMSAF dataset gives a more realistic estimate than the older PVGIS.
    Last edited: Feb 19, 2012
  6. danesol

    danesol Regular EF Member

    North West
    You say this FB but today was the best day so far for us this year generating 9.33kw, most of that was produced between 9.30 and 2pm ..... system kicked in at 7am and stopped at 5pm - Happy Days, we seem to be on our SAP target so far.......
  7. FB.

    FB. Electrician's Arms

    My SE-facing system continues to receive direct sun - albeit from quite a shallow angle to the side - until a bit after 2pm. An ESE-facing system, at this time of year, would probably get no sun from around 1pm, after which the rate of generation would be quite low in comparison to its likely peak around 10am.

    My inverter fired-up at 7-something this morning, with a rapid increase in the rate of generation until about 8.30am (about 60% of maximum potential), after which the rate of increase continued to rise at a slower rate until about 10am (reaching about 75% of maximum potential), where it plateau'd until about 11am. The rate of generation then slowly began to decline until about 1.30pm (about 50% of maximum potential), followed by a sharp decline in the rate of generation as the sun went off the panels and round to the other side of the house in the middle of the afternoon. By abut 3pm there was no sun on the panels and output was about 20% of potential, gradually trailing off until the inverter shut down about 5pm, although, in reality, not much was generated in the last half-hour; the inverter, I guess, was just hoping that it was a big cloud passing over and not the end of a glorious day!
  8. steve40x

    steve40x Guest

    we are in east midlands too, we only 1.5kw sanyo system sw facing and produced 4.1kw today which has been one of the best days so far this year and can only get better as the sun slowly gets higher in the sky as we get closer to spring, so i would say your system is doing fine.
  9. danesol

    danesol Regular EF Member

    North West

    Sounds like you have an efficient early morning to midday system and I an efficient mid morning to mid afternoon system, I wonder how we shall compare after the first solstice ?
  10. Orty

    Orty Guest

    A record day for us yesterday (Sunday) producing 15.8kwh. Peak times were between 10.30am and 3.30pm.
    Saturday gave us 8.8kwh.
    Best bit was watching the meter whizz backwards! Better than the TV.
  11. pwboston

    pwboston Regular EF Member

    I have a 4kw sanyo system, East Midlands, More South than South East I suppose, but yesterday (Sunday) was a very good direct sunshine day, and my system generated 19.56 KW. Where as Saturday we got 6kw.

    My Uncle who lives opposite but has a 4kw setup to you ESE 4kw, he got 11kw yesterday, so on that logic your not too far different to his uptake, pro rata
    Last edited: Feb 20, 2012
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