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  • FIRST POST
    • Kernel Sanders
    • By Kernel Sanders 16th Mar 12, 12:06 AM
    • 3,499Posts
    • 1,428Thanks
    Kernel Sanders
    Renewables: "talking 'bout my generation"
    • #1
    • 16th Mar 12, 12:06 AM
    Renewables: "talking 'bout my generation" 16th Mar 12 at 12:06 AM
    Please forgive the corny thread title inspired by The Who, but this post on the bloated 'how do I make the most of it' thread prompted me to initiate a new one...
    Hi Everyone,
    I haven't been here for a while, and am interested to see discussion of how much is being generated, rather than what to do with it.
    Originally posted by old grouser
    Well, there was yet another misty and bleak start in North Notts today (Thursday), but my SSW 3.92 kWp system was generating around 3kW for just a few minutes between 12.15 and 13.00, but enough to get the immersion heater hot enough for a shower. It seems to drop below that figure before it reaches 13.55 (optimum orientation). Final figure was just over 14kWh.

    BTW, there was an item about solar generation in Germany on the radio today; you can stream it here:
    http://www.bbc.co.uk/iplayer/episode/b01d2rvn/PM_15_03_2012/
    Just click on the speaker symbol on the left, then drag the time cursor at the bottom to 25mins 30 secs then release.
    Last edited by Kernel Sanders; 19-12-2012 at 7:01 PM.
Page 3
    • KevinG
    • By KevinG 26th Mar 12, 9:06 PM
    • 1,592 Posts
    • 4,701 Thanks
    KevinG
    Yesterday was my best day since 10th August. 11.2kWh, 2kWp, SSE facing, 37 degree pitch, north Sussex.
    Originally posted by KevinG
    And 11kWh today, despite thick fog until nearly 9am. Things are really ramping up now. Have already exceeded PVGIS for March by 20% and just exceeded SAF PVGIS.
    Last edited by KevinG; 26-03-2012 at 9:08 PM.
    • Kernel Sanders
    • By Kernel Sanders 26th Mar 12, 11:36 PM
    • 3,499 Posts
    • 1,428 Thanks
    Kernel Sanders
    Same curtailment of peak output as per yesterday, but another ½kWh added to yesterday's record nontheless; now 21.88 kWh. Had immersion on again, but thermostat cut in when bottom of cylinder barely warm. Why is this when it is turned to its maximum of 180°F?
    I'm here for just a few days' intensive motor insurance tuition so as to avoid another huge blunder. Please bear with me!
    • EricMears
    • By EricMears 27th Mar 12, 9:04 AM
    • 2,581 Posts
    • 4,463 Thanks
    EricMears
    Same curtailment of peak output as per yesterday, but another ½kWh added to yesterday's record nontheless; now 21.88 kWh. Had immersion on again, but thermostat cut in when bottom of cylinder barely warm. Why is this when it is turned to its maximum of 180°F?
    Originally posted by Kernel Sanders
    As usual I'm just a bit behind you (20.77) - almost certainly due to shallower pitch as I didn't see a cloud all day apart from a few contrails.

    Immersion heater is probably in top half of tank ? They're designed that way to give a quick boost to DHW so you can do a bowlful of washing up or have a (short) shower asap. Very little circulation in a DHW cylinder so water at stop gets hot and bottom stays cold. Doesn't matter quite so much with the coil you probably have heated by a gas boiler or whatever as (a) that's usually set a bit lower and (b) it's controlled by a tank thermostat which is also set lower in tank.

    You could try fitting another (pref low power) element at bottom of tank but doubtful whether cost would be justified.
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    • Kernel Sanders
    • By Kernel Sanders 28th Mar 12, 12:46 AM
    • 3,499 Posts
    • 1,428 Thanks
    Kernel Sanders
    As usual I'm just a bit behind you (20.77) - almost certainly due to shallower pitch as I didn't see a cloud all day apart from a few contrails.
    Originally posted by EricMears
    Yes, same here. I still think you will catch up (and, indeed, overtake me) before we reach the solstice.

    Immersion heater is probably in top half of tank ? Very little circulation in a DHW cylinder so water at stop gets hot and bottom stays cold. Doesn't matter quite so much with the coil you probably have heated by a gas boiler or whatever as (a) that's usually set a bit lower and (b) it's controlled by a tank thermostat which is also set lower in tank.
    Originally posted by EricMears
    Aren't all single element immersion elements at the top of the cylinder? I just want to get all the water as hot as possible so it will cover the next couple of cloudy days that we have. Is it possible to disable the thermostat? I remember about 25 years ago the water boiling in my cylinder with steam coming from the header tank! Can't remember if this was due to the element or the thermostat for the gas coil that you mentioned.
    You could try fitting another (pref low power) element at bottom of tank but doubtful whether cost would be justified.

    They're designed that way to give a quick boost to DHW so you can do a bowlful of washing up or have a (short) shower asap.
    Originally posted by EricMears
    The cylinder's quite old (possibly 35 years), so may invest in a stainless steel one. I'd want a small (500W?) element at the top so I can still have free hot water and that short shower in the winter.
    Last edited by Kernel Sanders; 28-03-2012 at 12:57 AM.
    I'm here for just a few days' intensive motor insurance tuition so as to avoid another huge blunder. Please bear with me!
    • EricMears
    • By EricMears 28th Mar 12, 9:32 AM
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    • 4,463 Thanks
    EricMears
    Yes, same here. I still think you will catch up (and, indeed, overtake me) before we reach the solstice..
    Originally posted by Kernel Sanders
    The optimum pitch for SS day would be approx 30deg (latitude - 23deg). Your 23deg is closer to that than my 17.5 - but we'll both be better off that day than anyone with a slope of 45deg.

    Aren't all single element immersion elements at the top of the cylinder? I just want to get all the water as hot as possible so it will cover the next couple of cloudy days that we have. Is it possible to disable the thermostat? I remember about 25 years ago the water boiling in my cylinder with steam coming from the header tank! Can't remember if this was due to the element or the thermostat for the gas coil that you mentioned.

    The cylinder's quite old (possibly 35 years), so may invest in a stainless steel one. I'd want a small (500W?) element at the top so I can still have free hot water and that short shower in the winter.
    Originally posted by Kernel Sanders
    Nothing easier than disabling a thermostat - just bridge it with a bit of wire. HOWEVER, nothing more dangerous than an exploding DHW cylinder ! I wouldn't risk it. You can certainly buy replacement thermostats and with a bit of hunting around you should find one with a higher setpoint than normal. My 'Heatbank' has two adjustable thermostats in series - one goes to 80, the other 90 deg C; may sound silly but I guess the idea is that if you choose to short out the 80 and rely on the 90 the manufacturer hasn't recommended that.

    If you're buying a new cylinder, I'd suggest you specify one with two (or even more) immersion heater mounting points. One high wattage one in normal place to give almost instant emergency DHW and a couple of smaller ones at bottom so that you can wire up one (or both - depending on surplus level) to 'waste' spare electricity. Additional cost over a standard cylinder would be modest but whole cost of an unnecessary replacement probably not justified (although copper scrap value might help pay for a SS tank ?) .

    I'll try & look up a contact for purpose built cylinders from the UK_selfbuild forum.

    http://www.newarkcoppercylinder.co.uk
    They are pretty handy for Mansfield but only seem to do copper ones.

    I've PM'd you with some more
    Last edited by EricMears; 28-03-2012 at 10:17 AM. Reason: url added
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    • EricMears
    • By EricMears 28th Mar 12, 5:10 PM
    • 2,581 Posts
    • 4,463 Thanks
    EricMears
    Kernel S :

    I have sent you three PMs today.

    However, looking at my 'MSE control panel' it says I haven't sent any !

    Please let me know if you received them. If not , perhaps you'd care to try and PM me with an email address and I'll reply with info about other tank manufacturers and hi-temp imm heater thermostats.

    Regards
    Eric
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    • Kernel Sanders
    • By Kernel Sanders 28th Mar 12, 8:17 PM
    • 3,499 Posts
    • 1,428 Thanks
    Kernel Sanders
    Thanks Eric, I've received all 3 plus the test PM. There's something wrong with the system, as I had a PM missing from my sent box a fortnight ago, but it was received. Won't have time to look at those links just now as I'm searching for docs in support of my 2006-07 tax refund (deadline 31 March!)
    20.02kWh today, nearly 1½kWh down on yesterday. Peak down to about 2870W; not sure why in a cloudless sky! I was peaking at around 3500 a fortnight ago.
    Last edited by Kernel Sanders; 28-03-2012 at 10:38 PM.
    I'm here for just a few days' intensive motor insurance tuition so as to avoid another huge blunder. Please bear with me!
    • EricMears
    • By EricMears 28th Mar 12, 9:12 PM
    • 2,581 Posts
    • 4,463 Thanks
    EricMears
    20.02kWh today, nearly 1½kWh down on yesterday. Peak down to about 2870kW; not sure why in a cloudless sky! I was peaking at around 3500 a fortnight ago.
    Originally posted by Kernel Sanders

    Funnily enough, ours was also slightly (1.2kw) down on yesterday. Peak 2.76kw at 12:40 (almost half an hour before true noon) with a distinct 'nibble' out of the otherwise smooth curve.

    High level haze ? Maybe even panels getting a bit warmer ?
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    • sly_dog_jonah
    • By sly_dog_jonah 29th Mar 12, 11:06 PM
    • 1,005 Posts
    • 1,211 Thanks
    sly_dog_jonah
    We exceeded 125% of our PVGIS estimate by 11am Weds, just before we set off for a few days away. Fortunately my Solo PV is logging away while we soak up the sun's rays elsewhere. If we've made another 55kWh then that'll be 1000kWh clocked up in total. Happy (sunny) Days!
    Cider Country Solar PV generator: 3.7kWp Enfinity system on unshaded SE (-36deg azimuth) & 45deg roof
    • KevinG
    • By KevinG 30th Mar 12, 8:10 PM
    • 1,592 Posts
    • 4,701 Thanks
    KevinG
    Wow. What a week! 76.17kWh in 7 days (2kWp system), exceeded 10kWh every day, completely smashed any period in the whole of last summer and now exceeded March PVGIS by 53%.
    • KevinG
    • By KevinG 31st Mar 12, 7:20 PM
    • 1,592 Posts
    • 4,701 Thanks
    KevinG
    What a difference a (cloudy) day makes. Only 2.5kWh today. So that's March over, it would be great to have an April like last year's (before I had the panels) but with some overnight rain to ease the drought
    • Martyn1981
    • By Martyn1981 31st Mar 12, 8:36 PM
    • 9,807 Posts
    • 14,755 Thanks
    Martyn1981
    OK end of March. Shall I go first to make everyone else feel better?

    System: 3.58kWp

    Total generation: 264kWh

    Generation per kWp: 73.74kWh

    Go on then wheel out the big guns!

    Mart.
  • GaryMo
    Hardly a big gun but a great month for generation, especially the latter end.
    PVGIS estimated figures for March were 262kWh, my generation figures ended up at 385kWh so much higher than anticipated at 147%

    My system on PVOutput

    Record day was 26th March with 23.47kWh
    Worst day was 9th March with 1.8kWh
    Average for March is 12.423kWh
    Generation per kWp - 96.25kWh

    Last edited by GaryMo; 01-04-2012 at 2:52 PM.
    16 x 250W JA Solar Panels (JAM6-60-250) : Fronius IG TL 3.6 Inverter : South Facing : 28 Degree Pitch : No Shading : Manchester M46
    • sly_dog_jonah
    • By sly_dog_jonah 31st Mar 12, 8:50 PM
    • 1,005 Posts
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    sly_dog_jonah
    Indeed it does:

    (light green is Today, dark green was Thursday - MSE auto-resize makes the image a bit small)
    Originally posted by seagull09
    What happened at 11:00am on Thursday? The steep rise? Cloud/mist burning off? Or is that when some physical shading ends?
    Cider Country Solar PV generator: 3.7kWp Enfinity system on unshaded SE (-36deg azimuth) & 45deg roof
    • EricMears
    • By EricMears 31st Mar 12, 9:20 PM
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    EricMears
    Well I haven't been able to report the bumper individual days others have - my best was 20.77kwh on the 27th - but monthly total is fairly respectable :-
    From SB logs
    01/03/2012 00:00 1248.575
    31/03/2012 19:25 1617.29
    March Gen 368.7kwh
    (92kwh per installed kwp)
    I don't actually remember seeing the sun at all today but still managed 5.28kwh.
    Roll on April May, June & July - every one of them ought to be better than March and of course my shallow slope gets less of a handicap.

    Cashwise, my £12k left in the ISA would have earned £420 in a full year or around £35 per month. March (containing an equinox day) should be an average month but I seem to have earned over £160 (getting on for 5 times as much).
    Last edited by EricMears; 31-03-2012 at 9:28 PM.
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
    • KevinG
    • By KevinG 31st Mar 12, 9:20 PM
    • 1,592 Posts
    • 4,701 Thanks
    KevinG
    OK end of March. Shall I go first to make everyone else feel better?

    System: 3.58kWp

    Total generation: 264kWh

    Generation per kWp: 73.74kWh

    Go on then wheel out the big guns!

    Mart.
    Originally posted by Martyn1981
    Mine works out as 101.52 kWh/kWP for March.

    Here I am on pvoutput.
    • sly_dog_jonah
    • By sly_dog_jonah 31st Mar 12, 9:53 PM
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    sly_dog_jonah
    I see a very similar kink in our graph in the afternoon when the whole pv array is shaded by the sun moving westward.

    How did your output compare to PVGIS? I guess PVGIS can't account for shading, so it would be interesting to see how it compares?

    I'll be uploading my stats tomorrow evening, but I know we'd beaten PVGIS by 25% as of Wednesday lunchtime.
    Cider Country Solar PV generator: 3.7kWp Enfinity system on unshaded SE (-36deg azimuth) & 45deg roof
    • EricMears
    • By EricMears 1st Apr 12, 11:23 AM
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    EricMears
    Was it worth it ?
    Certainly has been for us !

    I've just looked at all my (7.5) months outputs. To break even with leaving our £12k in an ISA, we need to earn £35 per month which was (until this morning) 78kwh / month.

    The only month so far in which we didn't do that was December - and even that was 77.8 so we weren't really much out of pocket even then (9 pence ! )

    Actual monthly results were :-
    . . . . . . . . . . . . . . . . . . . . . . . . pvgis
    Aug (15 days) 184 . . . . . . . . . . .390 (full month)
    Sep 347 . . . . . . . . . . .. . . . . . . .296
    Oct 262 . . . . . . . . . . . . . . . . . . . 195
    Nov 100 . . . . . . . . . . . . . . . . . . . 100
    Dec 77 . . . . . . . . . . . . . . . . . . . . 63.5
    Jan 107 . . . . . . . . . . . . . . . . . . . 91.5
    Feb 170 . . . . . . . . . . . . . . . . . . 149
    Mar 363 . . . . . . .. . . . . . . . . . . . 250



    excluding Aug :-

    Month . Act . . Pred . %inc rel to pred
    Sep . . 347 . . 296 . . 17.23
    Oct . . 262 . . 195 . . 34.36
    Nov . . 100 . . 100 . . 0.00
    Dec . . 77 . . 63.5 . . 21.26
    Jan . . 107 . . 91.5 . . 16.94
    Feb . . 170 . . 149 . . 14.09
    Mar . . 363 . . 250 . . 45.20

    Year . . 1426 . .1145 . . 24.54
    Last edited by EricMears; 01-04-2012 at 8:27 PM. Reason: adding pvgis 'indications'
    NE Derbyshire.
    4kWp S Facing 17.5deg slope (dormer roof).
  • KenS
    System: 3.50kWp

    Total generation for March: 347kWh

    Generation per kWp: 99.20kWh
    3.50 kWp : 14 x 250W Sanyo NU-R250-J5 : Diehl Ako 3800S Inverter : South Facing : No Shading : Hertfordshire WD3
    • sly_dog_jonah
    • By sly_dog_jonah 1st Apr 12, 11:02 PM
    • 1,005 Posts
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    sly_dog_jonah
    March was a corker here in cider country. PVGIS estimate was 244kWh and we generated 365.1kWh, so 50% above estimate. That equates to 98.7kWh/kWp.

    This was despite a rubbish week in the middle where we barely saw the sun for 5 days and only made 17kWh in that period. The last 2 weeks more than made up for it, we only had 2 days in the that period when we didn't break into double figures (and one of those was a 9.9kWh). We set 4 new records during the course of the month.

    Until March we were running about 25% ahead of PVGIS. I need to crunch the numbers tomorrow to see how we're doing taking March into account.

    April started off today with a new record at 22.155kWh which at the old FIT rates would have been just under £10, but with the uprating it was our first £10+ day at £10.39 (rounding down to 22.1kWh).
    Cider Country Solar PV generator: 3.7kWp Enfinity system on unshaded SE (-36deg azimuth) & 45deg roof
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