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Ivan
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« Reply #15 on: September 29, 2009, 10:29:02 PM » |
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Still going well on solar. Last few weeks have ranged from 43 to 59C end-of-day temperatures. Today was bright sunshine for half the day and bright overcast for the other half. End result - tank temperature rose from 42C to 53C. One thing that's particularly noticeable is that we're struggling to reach 60C now.
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Greenbeast
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« Reply #16 on: September 30, 2009, 08:19:04 AM » |
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i'm experiencing similar at the moment, very pleased as i've only used the boiler 3-4 times since installation in june and its almost october
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damnager
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Posts: 163
St Ives
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« Reply #17 on: September 30, 2009, 10:54:40 AM » |
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Down here in sunny Limoges (where we have had no rain since 9th August and we desperately need it) I'm still getting high 60's from 50x 47mm into 269ltr tank. Today is forcast 24 and wall to wall sunshine (again  ). But there is only 2 of us, (and SWMBO uses most of it) most days I see 6 to 9kw from the panels  Keith |
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dhaslam
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« Reply #18 on: October 01, 2009, 02:09:24 PM » |
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Despite five sunny days early in the month and continuous weather forecasts promising more sunny days later in the month the output at 8.3 kwh per day fell just below the August average of 8.4 kwh.
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rob26440
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« Reply #19 on: October 01, 2009, 03:11:38 PM » |
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September was a good month down in E.Berks. Daily kWh and average daily temp (average of readings at 0800, 1600 & 2400 each day) up on last year.
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S/E England. 30x58mm tubes, S/W facing 40deg pitched roof, 216L primary and 184L secondary cylinders, TDC3 with home-made, separate controller to switch between cylinders, 15mm tubing with min 25mm insulation.
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langstroth2
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« Reply #20 on: October 01, 2009, 11:36:23 PM » |
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Another good month
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Ripstop
Newbie
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Posts: 23
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« Reply #21 on: October 02, 2009, 12:56:41 AM » |
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My first year of Solar since Feb with 30 * 58mm and Resol controller and DL2 logger. 3L/min into a retro coil 210L pressurised cylinder. Boiler been on about 15 times since March for the odd poor days and baths! I don't think this is half bad really  Rip. |
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langstroth2
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« Reply #22 on: October 02, 2009, 10:59:51 AM » |
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I was puzzling why my KwH per month dropped steadily after June - just reflecting the poor summer weather?, interestingly I notice Ripstop recorded a similar drop.
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rob26440
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« Reply #23 on: October 02, 2009, 04:24:22 PM » |
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I was puzzling why my KwH per month dropped steadily after June If my cylinder starts off with a decent amount of hot water from the previous day then I don't get as many kWhs. Lots more when the cylinder is cold at the start of the day. I assume this is something to do with a non-linear profile of the heat required to raise the temperature of the panel as it heats up to meet the deltaT above the increasing temp of the cylinder water rather than the calculated amount of heat required to raise the temp of the water in the cylinder (ignoring losses in the system). Am I correct? Having hot water "carried over" happens a lot more in summer than any other time of the year, hence an apparent drop off in heat gain. |
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« Last Edit: October 02, 2009, 05:07:59 PM by rob26440 »
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S/E England. 30x58mm tubes, S/W facing 40deg pitched roof, 216L primary and 184L secondary cylinders, TDC3 with home-made, separate controller to switch between cylinders, 15mm tubing with min 25mm insulation.
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brackwell
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« Reply #24 on: October 02, 2009, 05:05:47 PM » |
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Every system on a particular day has a max theoretical acheivable water temp. where heat gain = heat losses. If the water is colder then the losses are smaller and therefore the temp. increase is faster. One can increase the KWh by around 25% if hot water is drawn off in the middle of the day!
i like to see what other tube nos/tank sizes are being used. Mine is 30 x47 south with a preheat system but it is early days for me but already am thinking inline electric heater to top up / insurance policy.
Ken
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Ivan
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« Reply #25 on: October 03, 2009, 04:28:01 PM » |
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I think your reduction in heatloss is due to pipeline losses which increase dramatically as pipeline temperatures increase. This also tends towards significant further gain reductions if the solar input is limited (eg overcast days).
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