Tuesday, February 23, 2010

Solar roof hits 500.0!

Feb 22: Our OfGem meter finally hit exactly 500.0 kWhrs today, this is the amount harvested since 1 October 2009. Although our target is 2800 in the year, you might think we are behind target because that is nearly 5 months. But taking into account the angle azimuth and latitude, we are actually ahead of the target. By the end of Feb, we should have harvested 480 kWhr. The majority of the power comes in the summer months.
The image here comes from the website Sunnyportal.com and you can do a search on 26,000 sites around the world, all of whom use the SMA inverters. Put in the keyword 'Peveril' and you find ours. It is interesting to surf the countries and installations to see what others are doing (if they post photos).
By the way.... I had a Plumber visit at the weekend, and he is proposing to make the final connection for the heatpump on thursday of this week..... errr... thats postponed another few days... we still live in hope.

Monday, February 8, 2010

Planning Application for more

7th Feb: I just realised that it's precisely 3 yrs since the Planning approval for the solar panels on the south wall - 8th Feb 2007.
Just to make sure, I sent to Rushcliffe BC a request for an extension of time, and a drawing showing the amendments to the arrangement of panels - with the thermal panels above, as built now (actually, Permitted Development), and the tilting PV solar panels as proposed.
Because the PV panels fold flat against the wall, they are probably Permitted Development (although they will spend most of their time more than 200mm from the wall). Therefore, I thought I would put this in for safety (as, theoretically it is free, being a follow on to a previous approval.) I would also incorporate a small metal folding platform under the windows, strong enough to stand on : but this would live in the garage and only be brought out when needed.

Glycol and Meter arrive!

7 Feb: Well the next stage can proceed as Ice Energy have sent 20 litres of glycol now. They have also sent an energy flowmeter, Sontex SuperCal 539, which can compare the flow and return to the panels.

I spent part of Sunday doing the compression fittings in the loft. Looks like a complicated piece of kit when it is all plumbed together!

The Supercal can also show Volume and temperatures if you know how to press the button correctly. Minor complaint is that it will only show to the nearest round KWhr, not to decimal places.

Monday, February 1, 2010

Reflections on the work

Feb 1: Until the Glycol goes in, I am still not in a position to know if this will work overall, but with the number of holes drilled in my south wall, it's going to be a sad and messy thing if it does not work! Even if we only put heat down in the summer, it is worth trying.

Climatically, I have noticed that being 5-6 weeks after the Solstice, there are significant amounts of sunshine daily (even if the air temperature is cold). So we would get sunshine directly, and the air temperature inside the boxes would also contribute to the harvest of the panel.

Sunspace effect: I make the suggestion that the idea of building glassy boxes could be linked either to an airbased heatpump (drawing heat from air in the trombe wall effect behind the polycarbonate), or indeed using MVHR (mechanically ventilated Heat Reclaim) with the first air being drawn through a larger space behind a glass wall - a shallow sunspace in effect - in fact, MVHR would be tooooo hot, you need a heatpump to adjust the temperature up or down as required.

Polycarbonate: I know know that for serious buildings, you could not build with Polycarbonate as it is far too easy to drill and cut and no building would be secure against someone with a hand held power drill or cutter (unless it is so high that it is out of reach). Without stiffening, it could have a tendency to behave like a Rolf Harris's wobble-board. However, for domestic use, I know that I could not have done this if I had pre-ordered some sheets of real glass - because of the weight, because of the drilling and curved cutting, and because it is structural, i.e. cantilevering and prone to flex in the wind, etc. For a serious commercial building there is little doubt that the boxes would have to be better designed in Glass with all holes pre-located, making the whole thing a lot more expensive.

Insulation: My biggest worry now is the amount of Insulation required for the indoor piping. This may not be such a problem in the loft, where the surrounding air is colder and drier, although of course it will still be insulated. The insulation I am using is 19mm, and it's difficult to fit around the pipes at any junctions or turns. I shall need lots of self adhesive Insulating Bandage at all junctions and at joints with objects, eg Valves, Air releases, Flowmeter or Pump.

Condensation:  My bigger worry here is Condensation where the pipes pass through the house, close to timber joists etc., where there is plenty of warm damp air. With Hotwater systems, insulation matters merely to retain efficiency (avoid heat loss). But the hot water in the heating pipes cannot set the house on fire, or cause harm. Some installers dont even bother to insulate on the grounds that heatloss from narrow pipes is small and is escaping to where it is wanted, i.e. it becomes an 'internal gain' in the house. By comparison, Cold (below room temperature) plumbing turns out to be a real headache, as the insulation needs to be 100%, including bandage and duct tape everywhere - a small gap somewhere could precipitate damp patches, or worse, the watery equivalent of fire, i.e. dry rot. Small amounts of warm air getting access to the cold pipe can set off a trickle, perhaps making a joist permanently damp, with damp spreading into the ceiling.
     The whole system will have to be checked carefully, with the circuit pump on and the heatpump turned off, so that I can check all joints for leaks (so I don't see condensation and think that it is a leak). Then, when the heatpump takes over (as it must, during winter) any liquid which forms will be condensation, not leaks. As there is no going back on this I have to make it work, so am prepared to put drip trays in the loft underneath parts of the piping, either a wide rainwater gutter or planting trough drip trays.

Replicatability: This is a prototype, and one of the benefits of a blog is to record the problems that occured along the way. I have a CAD model of the panels and boxes, and a real one to measure off, so a future one could be manufactured with accurate dimensions, 1/4 of the effort, and an even smaller fraction of the risk. I also know if things are too over-engineered and stiff, or too flimsy and flexible. Even the choices of screw and bolt sizes has evolved.
  I somehow think that this experiment will have to have a significant benefit for the coefficient of performance of the Heatpump for them to think that this is a system worth offering commercially.
   Meanwhile, the heatpump is using more and more of the Immersion heater function (as the ground gets colder), there are plenty of sunny days up top, so I really want to get this working, even if only to benefit our house. If others can use it later, that will be great!

Panels Revealed for Nottingham Post

1 Feb 2010: I was told that the Nottingham Post photographer might be calling for a photo for a feature about the new Photovoltaic Feed-in tariffs.
   Therefore, I decided it was time to peel the white plastic off the face of my Surya-1 Sunboxes. The white plastic skin has been left on to keep them clean and to avoid too much heat build up while the black chillers inside are dry. The Nottingham Post readers would be confused with those large white boxes if the article is mainly about PV panels and tariffs, so the white plastic has to be peeled off.
    They look a lot better as transparent and shiny. I have to clean out some of the brickdust which built up inside when drilling more holes for the tilting rootlets.

Postscript: Agh! He didn't call, as they wanted to photograph a commercial property, but I hope the Nottingham Post will do a feature at a future date.

Post Post script... 2010 they did a feature a few months later.
http://chargingtheearth.blogspot.com/2011/01/nottingham-evening-post-writing-about.html It was another month, the 2nd week of March 2010 before the plumbing was finally connected and turned on.

Post Post Postscript ... August 2011. These original sun box outer cases have gone now, and are replaced by more efficient new design, a single large Sunbox, called Surya-3. See this posting:

Post Post Postscript ... February 2012: Plans are in hand for the system to be further augmented with an array of evacuated tubes from Kingspan, on the spare space on my east roof.
Surya-3 Sunbox under construction, August 2011

Post Post Post Postscript... May 2012: The evacuated tubes are in place, along with a heat exchanger, and the system is working fully - with data recording to see how it works through a full year. The next plan is to fit ETFE to the front panels.

Post Post Post Post Postscript... Jan 2013: The sloping front panels got changed to ETFE panels which allows in more thermal energy - and the wall below now has an extension with another sunbox on it, roof mounted.

Why is this the most frequently read blog item in the entire Charging website? Please answer in the Reply / Comments below. What is it about the Google link that makes this page come up first?

Feed in Tariff News!

Monday 1st Feb is the date for the government to announce the decision on Feed in Tariffs. It seems that the rate for generators is better than expected, it will be 41.3p/kWh for domestic PV generators, plus 3p for units sold to the Grid. This is for 25 yrs.
   For people who wait 2 yrs (2012) the amount paid will degress by 8.5%, and by that amount every 2yrs thereafter. So do it sooner!
Apparently, it will be index linked. We don't yet know if the rate for installations larger than 4kW are progressive or banded, i.e. if we add three more panels, do we get 41.3 for the first 22 panels, and only 36 for the ones after that... or does the whole installation go to the next band? Good news, and it makes the economic calculation for PV even more beneficial.

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