Thursday, December 31, 2009

Happy New year

Dec 31: Happy New year to all the kind folk who have been reading this Blog....

     the project isn't finished - but its moving along.

           Now, I must get up to the loft and do more plumbing! I am now working on the vertical descent from the loft to the heatpump on the ground floor. It is very difficult working through an underfloor heated floor, with the risks of losing sand or cutting a plastic pipe.

Rushcliffe Solar now has a blog!

31 Dec : The Rushcliffe Solar campaign now has its own RushcliffeSolar blog and its own email. More articles will follow about that on the new blog, including parts of the original powerpoint to Rushcliffe, with images of solar roofs, tables and details.

Moving the Rails - get it right!

31 December: Thinking harder about the problems of the position of the panels, I decided that a thoroughgoing approach was required - take two of the panels and rails off,  drill new holes in the aluminium for refixing to the wall, and then to refit the panels from new with the main rails perfectly plumb, and 3cm to the right. This was forced on me by the fact that the polycarbonate panels are perfectly square and require perfect squareness in the rails.

This was a difficult decision, but made easier by a visit from Chris McCabe, a builder (and contemporary of my daughter) who has helped other families in our West Bridgford friendship group. He stayed for a couple of hours - it is much nicer and more decisive working with someone on scaffolding in freezing temperatures, a lot quicker, and we finished with plenty of daylight left.
Later in the evening, I got more plumbing done in the loft - it's time to do the vertical piping to the ground floor! The photograph above may not look different from earlier ones, but close up, and millimetrically speaking, it is perfectly plumb and ready to fit the glassy boxes!

Tuesday, December 29, 2009

Better harvest from the Solar Roof!

There is one benefit of having passed the winter solstice...  bit by bit we shall see improved average harvest from our solar roofs! (although for a couple of weeks either side, the sun's altitude only varies minutely).

My roof is performing better than predicted by the JRC solar calculator, even allowing 10% efficiency losses. The harvest is 7 percent better in Oct, 40% better in Nov and so far, 45% better in December..... (December has been sunnier than average) .
This is pretty good, especially as our winter sunrise is a full hour later than the real sunrise due to our being so close to Sharp Hill. The morning is our only chance for harvest. Air temperatures are colder than average for December, so has this been enough to improve the performance of the panels?

Thursday, December 24, 2009

A day of adjustment - fixing errors

23 Dec : a Horrible day, entirely my fault, although the nice thing is that the sun shone all day and made the work warmer. I wish I had been more precise about measuring the centre of the group of panels, I just worked from the centre-pipe which I thought was central. But it shows yet again how important accuracy is. The left hand array should have been 2 cm to the right, and the right array would have been better if it had been 4cm to the right. In each of the arrays, the pair would have been better a centimetre closer to each other. Seems small, but matters a lot when trying to fix all those bulky 40mm pipe fittings and stiff rubber hosing, with all the jubilee clips required.
   I was close to taking the whole lot off and drilling yet more holes in the rails, to refix them.... but thankfully, there was enough 'give' in the fixings to move them sideways, enough to fix the stiff rubber hosing.  By now it was dark, and I hope all those Jubilee clips work well! They certainly make it easier to fix the hoses!
   Later in the evening, back down at ground level in the conservatory, I fastened aluminium angles to the Polycarbonate front panels (large!) using pan headed screws... this all went well, although its difficult to handle such large panels on my own.

Monday, December 21, 2009

Four Panels up!

21 Dec: Four panels up now. The curvature is because they are dry inside, so the front is expanding thermally, but not the back. It's lucky I have 8mm bolts holding them on in 14mm holes - so there is enough play for expansion. Also, the panels have compressible foam backing, and rubber washers on the front so there is further play for expansion. The bolts are not done up tightly - Nyloc bolts ensure that they are secure even if left with easy movement front to back.

Actually, I am glad they are loosely fitted, as I need to shift the far left one a centimetre to the right... this is possible. It is alarming how precise things have to be with metal and plastic. One is used to the easy tolerances of brick and timber, but metal and plastic need millimetre accuracy, like modelmaking. I had about an hour and a half re-plumbing something that I did too quickly the day before and the pipes were a centimetre too short when projecting from the wall.. it seems better to make things oversize.... (and cut back if too long).
As the technology here is a prototype, one has to be so careful and methodical. It is all modelled in ArchiCAD first - this has made it possible to make detailed cutting lists for the panels and metal sections. When the whole thing is complete, I will draw up a list of components and dimensions, so that it can be replicated.

Solstice sun

21 Dec 2009: Well Dec 20/21 are both Sunny Days! A great time to calibrate the roof performance. Dec 20 had a short period of cloud which modified the PV harvest to 3.99 when it should have gone over 4.0.

Sunrise in Nottingham is 0816 on Dec 20/21, but the annoying thing about living in the shadow of Sharp Hill is the late sunrise in Winter. I watched the sun rise, but Peveril-sunrise didnt happen until 0918, 62 mins after the real sunrise. We get daylight in the mornings, but can only sense sunlight in the sky, but not see it on us!

GAISMA seems to be a really good site, with predictions for sun angles and declination, both in tables and in good diagrams. Plus info on insolation, wind and temperature. (the word means 'light' in Latvian)

By 0925, when the sun has fully cleared the hill, the roof is generating 310W, and by 1018, an hour after Peveril-Sunrise, its getting 1240W. We pass our peak at about 1030, so at 1118 the power was 1120W..... at 1200 was 800W.... and from now it's downhill for the rest of the day :(

Sunday, December 20, 2009

First Panels go up!

Dec 20: The sun shone all morning, so I got all four panels up.
Just as I finished, the sky grew dark and filled with snow, so I don't have a photo of all four, but here is one of the first panel going on.
All the panels fitted well and the biggest problem was fixing the stiff rubber hosing to join them together. The panels immediately responded to the sun, and you can see how this one curves as the front face is hot and the back face cold - when liquid flows through, the temperature will be more even.

The sunshine of the morning gave us an excellent haul of 3.99 kWhr and by the time the snow came, the sun was well round to the west. As today is the Solstice, this gives a good calibration for what the PV panels can achieve. Lets hope we have sunny days on June 20/21, Mar 20/21 and Sept 20/21.

Addition of three tracking panels?

I have in mind to increase our PV installation, but instead of more on the roof, there is room on the south wall for 3 more panels which are tracking. I could design and build the tracking frames.

I would like to know if or when there is a change in the kW rating assessment for banding of the Feed-in tariff. ie is it globally 31p if you go a step over 4KW, or if it is progressive (ie any amount over 4kW is at the lower tariff). Presently, the 36.5p per kWhr applies to systems 'nominally' under 4kW, not actually under. Its not known what happens if you install 4.4kW nominally, but because 4kW of it faces east it would never generate that amount in reality. Does the whole lot go to 31p or only the amount that exceeds 4kW?

Only three panels - 540W nominal, would generate a massive 583 kWhr in a year if tracking - eg one would change the angle every 2 months to maximise the harvest (easy to work out the perfect angle.)
The two windows open inwards, so one can simply open them and adjust the angle with bolts. Here you see a Winter, Summer and Equinox setting, from left to right.
I have written to EvoEnergy to ask. I wish I had thought of this earlier and had three fewer on the roof. I am keen enough on this idea to think that if I really am limited to 22 panels, I will have three moved from the roof to the wall.

Saturday, December 19, 2009

Rails go up onto wall

19 Dec: The Forest game was at 5.20pm which was great as it left all the daylight for getting some outdoor work done. I have had the Rails finished for some days now, so was desperate to make more progress. The Eight holes were drilled, and the rails are now held firmly by anchor bolts, all in the correct location.
I have been slow because I realise the need for extreme accuracy - almost like modelmaking - the spacing of the holes on the panels gives little scope for mistakes, and I already have 8 unwanted holes that I drilled last week and then realised were in the wrong place. So accuracy is essential, even though it is time consuming. I am building a prototype, so have no precedent to work from. I have to think it out through design, and then cut or drill accordingly.
Let's hope that the Polycarbonate panels (when they arrive) are cut accurately by the suppliers and need no further trimming. If so, they will fit perfectly with minimal cutting and a lot of accurate drilling.
By the way..... Forest beat Preston 3-0 at home. I think that is the 14th unbeaten game in a row.
Another By the Way..... we seem to be weather-lucky as the forecast for the 20th-21st Dec is for a clear sky and high pressure, meaning that we hope to get a classic solar bell-curve indicating the maximum PV harvest possible at the moment of the Winter Solstice.

Thursday, December 17, 2009

Making the metal rails

Dec 16: I have picked up all the aluminium angles from the University engineering stores, and have borrowed a platform drill. So the evening was spent enjoyably building the metal framework to support the panels - in freezing temperature....

I feel a sense of liberation - its been 46 yrs since I last did any metalwork, and with the right tools, it feels like a creative task - and now I am well into it, I feel less anxious about it. Also... one feels that one can make anything that one can invent - [I might make a metal gate for the house next, as it's impossible to find ready made gates that are the right size.] Many thanks to Adrian Harms for the loan of the pillar drill.
The Polycarbonate is coming soon, so that will be challenging - two glassy boxes 1.8m x 1.65m is quite an undertaking to build, and another challenge is to lift them 6 metres.

Dec 17: I have also realised that the temperature inside the polycarbonate boxes could become so excessive - perhaps 40ยบ plus which could affect the liquid tightness of the joints, or overheat the plastics.....  - that I need to have a precaution for this by permitting Ventilation. So the bottom panel will have vents, and the top panel will become a tilting panel, with settings for Winter, Equinox and Summer, allowing appropriate amounts of ventilation. There was a chance to buy an automatic solar powered ventilator fan, but this would be automatic, so I did not get it (saving £ 80).  I prefer to try ventilation settings and see the results.
For research, I prefer to have manual settings that I can experiment with, and measure resulting temperatures, at different times of year. Using a Trombe wall based on this construction, and a MVHR (heat reclaim ventilation) you could go a long way towards heating a house using this method.

Dec 18: Still very frustrated that the Polycarbonate has not arrived... I am told it will come on Monday.

Sunday, December 13, 2009

Drilling holes for the metal structure

Dec 13: This is a view from behind, of the panels and the Polycarbonate boxes. The holes have been drilled in the wall for all the anchor bolts. I will have 50x50 angles top and bottom, which can support the panels and the boxes. I was going to make the boxes of pure polycarbonate using 8mm with patchplate brackets, but have now ordered 6 mm (for lightness and greater transparency) and will have small Aluminium angles at the corners. I will now have the boxes completely closed (including a soffit along the bottom), and the only ventilation is around the entry/exit pipes. This will build up a good temperature inside.
   I hired a diamond tipped coredrill to make the 32mm holes through the wall for the glycol pipes.
    Only disadvantage of the glassy boxes is that I shall have to sense the temperature of the panels by checking the pipes in the attic, as the glassy surround will stop me reading the temperature externally with an infrared thermometer.
    The same effect keeps the heat inside as the panels cannot lose heat by radiating outward through the polycarbonate. They will radiate back to the brick wall. I have contemplated facing the brick wall with reflective foil, but on balance there is a beneficial thermal storage effect from allowing the wall to get hot, and this will keep the space warm after sunset.
I have a difficulty picking up the metal angles, as the car is being repaired at the moment. I have the scaffolding now till early Jan, so there is time to do it well.

Dec 14: spent a while in the Faculty of Engineering stores deciding on the final cutting list requirements for the aluminium sections and the bolts - which can be collected later in the week.

Saturday, December 5, 2009

Scaffolding goes up in one hour!

Dec 5: these guys don't hang about! The 30 cubic metres of scaffolding was up in a flash on Saturday morning, I had time only to make them some tea and take some photos, and it was all done!

And Emperor Scaffolding of Leicester were kind enough to leave some old planks for me to use in the Veg garden. I have the scaffolding now till the first week of Jan.
And I now feel slightly guilty that Forest hammered Leicester 5-1 on the same day! :)
(still... football is more important than Life and Death, as Bill Shankly said famously)

Electrorad offer Solar Geocharging fence

5 Dec: Here is a product that is specifically linked to solar earth charging, although its too new to appear on Electrorad's website. It's called ThermoSolar Fence. [ ]

As this is specifically for Heatpump, I guess my friends at Ice Energy should add it to their inventory. I would recommend it - now we are reaching the solstice, I suspect my heatpump will using increasing amounts of immersion heater instead of ground heat. This fence is another good idea, although it should not be overshaded by nearby bushes or trees.
A few metres of this, above and below ground, and not overshadowed, would probably be enough for a whole house, combining the benefits of air-solar with the battery effect of the ground - saving the cost of deep boreholes.

Thermosolar on World Architecture News
(its important to look at the smaller pictures which explain it well)
Greendiary page on the Thermosolar fence

Perfect December curve

4 Dec '09: We had a cold but sunny day, without a single cloud all day. So the solar harvest is short but very clean, and represented a total of 4.5kWhr, the best that a December day will do. We have a hill to the south of us, which explains why the bell curve is so steep at the start. Normally when sun rises, it is starting in a haze and the bell curve rises smoothly. In our case, the sun in December has already risen, and it peeks suddenly over the hill at full strength - so the curve is nearly vertical. After noon, the power is coming from the bright sky, not directly sunlight.
The best day in October was 13 kWh, the best in November was 7.6 kWh and the best in December 4.5 kWh. So, of course, I am looking forward to seeing the figures improve after Dec 21, as we move to the spring and summer.
Total for October was 184 kWhr and we got 109 kWhr in November.

Friday, December 4, 2009

Red Light Immersion panic

4 Dec : Every so often, the heatpump seems to malfunction. I had set it so that the immersion heater should not come on, but there must be ways in which it overrides that. Today, it had a redlight moment in the afternoon (possibly not getting heat quickly enough) and then the Immersion heater comes on... it was on for FOUR hours today, more than in all the autumn. As a result the power consumption was 10 kWhr more than usual. And when it is on, the heat pump does not circulate to the ground at all.

This underlines how important it is to get on with this installation of the solar-air panels.

Scaffolding and Polycarbonate

Dec 2: I have booked the scaffolding for Saturday - for the south wall. I feel that progress is stopped until the panels are up.
   Had a tutorial with Joel Carter of the MEng course on Monday, and evolved the design further - we had a thorough discussion of the benefits of putting a glassy screen in front of the panels to foster a microclimate that would increase the air temperature around the panels - a sort of Trombe wall effect.
So in the evening, i have researched the stock sizes of Polycarbonate sheet  and worked out the optimum sizes for a sort of glass box that can surround the panels - if I leave it till another year, we would need the cost of scaffolding again, so it's worth doing all in one go.
    There is an interesting discussion between me and David Brook just below this posting, discussing the idea of glassing in only one of the pairs of panels, to compare their performance.

In the image above, the South Wall panels are rendered in ArchiCAD and photoshopped onto a photo of the house and PV roof. So we are hoping to capitalise on the 'Greenhouse Effect'.

Postscript Dec 10th: I have now ordered the Polycarbonate, more than 400 quids worth!! enough to make two large boxes, as above, and it will now be very closed, eg there will even be a Polycarbonate soffit going in, to make the air inside very hot. The outer leaf of the brick wall will get hot in Summer, which will prolong the thermal benefit long after sunset.

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