Wednesday, May 25, 2011

May 2011 Reports

Every Sunday evening, I take meter readings and compute the annual consumption and generation figures. 

29 May 2011: The last week has been mostly cloudy, and PV figures have been poor. The house total and the GSHP total are again lower than ever, with 5,316 and 3,340 kWh respectively. The Sunboxes have been very quiet because air temperatures are moderate but not hot, and the GSHP using less than an hour a day of power for water heating.  The PV is getting close to the 5,000 kWh line (since installation in Oct 2009).

22 May 2011
I've been away most of the week, in Prague for the Isover world final. But it was a sunny week, and the family were still here. As with the previous weeks, the Annual consumption just got better again, still lower than last week. At this time of year, consumptions are so low due to it being Summer that progress slows down. One bad day in the Winter is equal to an entire week in the Summer. Daily incremental gains or losses in Summer are too small to take seriously. So, let's enjoy it for now, and recognise that I will really know if this is proven by seeing the Winter performance in 2011-12. Ground temp is the highest this year, at 12.7º, but with reasonable sunshine and little use of the GSHP. I am disappointed that it is not over 13º by now. Patience, friend, patience!

Postscript 2.1.2012: Isover have published the student work on a website Another point is that at this time in May, I expected the figure of 5,300 and 3,300 to be the incompressible lowest annual consumption figure, but postscript writing on 2 Jan 2012, the figures are 4,650 and 2,650 respectively!

15 May 2011
It has been a colder and less sunny week, but the same week last year was cold, so our system continues to break the record. This can't continue, but let's enjoy it while it lasts. It will level off when the effect of the mirrors have worked through the system, and if the autumn quarter of 2011 is warm, then the consumption figures will reduce even more!
• House electrical at all time low of 5,330 kWh
• Heat Pump consumption at all time low of 3,350.5 kWh
• Sunbox capture all time high of 3,091 kWh
• The PV power seems to generate an average of 3,280 kWh, oscillating between a worst of 3,236 and best of 3,322. There is no prospect of that changing as the number of panels are at their optimum.
• The Ground temperature is 12.4º. A year ago it was 11.7º, sometimes touching 12º.
Summary: I didn't expect the House to go below 5,600 kWh/yr and the Heat pump to go below 3,600 kWh/yr, and I hoped the Sunboxes would achieve 3,000, and I might have settled for those figures. But they have done better than all of those and they keep getting better! I would have hoped for a higher ground temp than 12.4º, it is only slightly higher than the same time last year - although at this time, the SBs had already been working for 2 months.

8 May 2011
Weather: Although the hot weather has broken - plenty of rain last night, the temperatures are still warm and the garden is blooming with seedlings and green shoots from things which seemed to have died in December's frost. Amazing how the botanical world can tell the difference between real rain and water from a watering can. Seeds are shooting up in the last two days after a month of sitting tight underground. This fine weather has certainly helped to make our figures look better than if this Spring had been identical to Spring 2010.
   As for the solar and heating data... more records being broken as usual. Annual totals are recomputed every Sunday, so how's it looking?
• The house electrical has plummeted downwards through the 5,400 kWh barrier (it was 6,300 kWh last December, and averaged at 8,500 kWh in the two years preceding this project) This takes into account the greater economies of the heat pump being augmented by the Sunboxes, and the benefits of the PV roof which must be contributing about 2,000 kWh per year. Although it generates 3,250 kWh a year, my estimate is that we are using 60% of that, not 50%.
• The heat pump consumption has plummeted through the 3,400 kWh barrier. This includes the space heating, DHW and Underfloor circulating pump. Only a bit more and we can close the circle - to meet the PV power generation of 3,300 kWh.
• The Surya Sunboxes heat buried during the year has risen to an annual figure of 3,070 kWh. There is no space heating at this time, so this is entirely due to general sunshine and a tiny amount of GSHP demand when hot water is needed. The birds and atmospheric dust are making the foot mirrors dirty, so I did a bit of cleaning yesterday.
• See

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