Friday, November 24, 2017

Slough basin–what’s next?

Yesterday we completed the washwall vegetation survey of the Slough Arm.  Not a particularly exciting volunteer job, but eventful in its own way.  They gave us a nice little phone app with which we send in photos and comments of any woody vegetation needing cutting back.  I suppose recording the GPS position, writing a comment and taking and sending a photo direct to the survey database takes no more that thirty seconds each time.

There is a bit of news to report.  The old Travis Perkins yard and buildings down at the Slough basin end has now been cleared, so now the basin area has a cleared and empty building site for development.  Maybe something exciting will happen.   What will it be?  Luxury flats? A hotel? Affordable (huh!) housing. Maybe a revamp of the moorings – that would be splendid. How about a nice little park or garden?  Hmm even as I write that I realise it might well be taken over by the oiks and their lager cans which are now evenly distributed along the hedgerows down the Slough end.  I did notice that a CRT water tap had been installed down there, probably for winter moorers although there are none down there.  What ever is planned for the area,  I advise against holding your breath.

It was at that point, furthest from where I had left my car, that the pedal crank fell off my bike.  Doh!  I did in fact have two spanners with me, but of course neither of them were the right size.  We managed to effect a temporary fix which lasted about five minutes, so we had to push our bikes for half of the way back. A lot of the towpath down their is very muddy, so the fun was quickly evaporating from the day. Stopping to eat our sandwiches at the field where they hold the canal festival, we noticed that my beloved pair of long handled loppers had gone missing, so poor Christine (my volunteer partner for the day) had to cycle back to the basin to find them.  Thankfully she did.

The water down the Slough Arm tends to be very clear, mainly because very few boats get down there to stir up the mud, so it was easy to see the traffic cone standing on the canal bed in the middle of the bridge hole at bridge 10.  Had we been on a boat with some sinking rope I reckon we could have got it out somehow, but from the towpath there was nothing we could do to yank out what was undoubtedly prop fodder for some unfortunate boat.  Having said that, the likelihood of any boat going down there in the next month or two is pretty remote.  Anyhow this morning I decided to rend in a report of it to CRT.  Will they bother to send somebody down there?  Answers on a postcard…

Saturday, November 18, 2017

Solar panel tilting frame – tweaking the design

Now we’ve bought a second solar panel, I’ve been working on a tilting frame for it, and I thought I’d share how I did it in case anyone else wants to get one.

I’d settled on a design like this


which you can buy from a few places on line for £35 or so.  The idea was to have it so that I could have the panel secured flat for travelling or tiled to 40 degrees from horizontal to get the best radiation. Apparently 40 degrees is what you need for optimum average performance in the southern half of the UK.

I costed up the bits I would need to make my own, using aluminium for which was the cheapest place I could find and I could have saved a bit, but factoring in the postage and the cost of the screws and knobs it didn’t save a whole lot, so I decided to buy the ones shown above and tweak them to my requirements. Here’s where it gets interesting.

The kit you get is pretty sturdy, but in my view it isn’t ideal for use if you want to be able to have the panels quickly adjustable from locked flat to tilted, especially if you want to be able to choose whether to tilt port or starboard at any given location.  For a start, the holes on the "hypotenuse” don’t match up with those on the base when you lie it flat, so you can’t lock the panel down with the screw knobs.  Secondly, because the hypotenuse is longer than the base, it’ll only tilt one way unless you unscrew everything and slide the panel to the other end. If you think about it, the bars have to meet at a point at the fulcrum end , otherwise the overhang would hit the boat roof before you got it up.  I suppose if the bottom piece was longer than the top, it wouldn’t be a problem. But then you’d have sticky out bits of frame to catch on your boat’s centre ropes.  Sorry if you’re having trouble envisaging all this, I’ve had rather longer to mull it over.

Luckily, I’m building these for two panels of different widths and so by buying two kits I was able to mix and match the components to make frames to suit my requirements.  My new panel happens to be nearly the same width as the “base” piece shown above, so what I’ve done is to take those pieces from both kits and make a frame with the base and the hypotenuse the same length.  The holes match up to lock it down and I can get very close to 40 degrees tilt, like so:


The prop piece will have to be removed when the panel lies flat. Here you see it all upside down of course  so you see the feet sticking up.  I have it face down on the table to prevent it from generating electricity. As you can see, a range of angles is available, so in winter I can tilt it more if required.  Whilst I’m on that subject, on our old panel I have monitored the difference in amps between lying flat and propped up and the difference is significant.

At the other end of the panel you can see the frame folded and locked flat.  here’s a better look at it flat.


The fixed side of frame is bolted to the end frame of the panel by four screws and locking nuts. The feet I had  to buy separately. They have a small amount of wiggle so they’ll lie flat against the curvature of the boat roof.  Once I’m happy with the setup on the  boat I’m going to glue them down with Sikaflex.

There was one further problem.  The tilting edge wouldn’t go up to the required angle until I chamfered off its corner like this:


Otherwise it interfered with the other half of the frame.  Incidentally, you can see here that the aluminium itself is of a good thickness.

So that’s one done, and the bits I have left are long enough to do my old wider panel the same way.  You have to get lucky sometimes.

Monday, November 06, 2017

I learn more about solar - after a fright

Phew, my feet ache after trapesing up and down the eastern half of the Slough Arm today looking for woody growth (see my previous post) in the edges.  We didn’t find a lot but sent in about a dozen or fifteen reports, mostly of saplings.  The most surprising thing we saw was a boat actually moving down the arm, so rare that we almost sent in a report of that!

Now then, solar.  Well I ordered a shiny new 120w monocrystalline panel from Midsummer Energy.  I chose that one because it is narrow and ought not to interfere with centre ropes on the roof of the boat.  I had adapted my new stands (more of which another time) to the specific width of the new panel and was just about to drill the fixing holes in the panel frame when I thought I should just check the specification label on the back of the panel.  My heart sank.  What was this? The open circuit and max power voltages were at least two volts higher than the spec on Midsummer’s web site.  Was all my research and thinking in vain? Would this mean if I connected up in parallel to my old 95w panel that the new one would be dragged down below its proper performance?  “Woe is me” I might have said, except I said something rather less printable.

To cut a long story short, after a dialogue with the tecchies at Midsummer it’s OK.  As I had explained in previous posts, they confirmed that series connection was a No No in my case  but when in parallel, the MPPT controller will hold the voltages from the two panels at an appropriate level and they’ll perform as well as expected  99% of the time.  That other percent is that rare occasion when the sun is out in the perfect position and everything is at max power, then my 120w won’t quite make all it could, but still comfortably over 90% of what it could.  The rest of the time on normal or dull days the panels will perform just as they should, which in this case is better than most panels because this particular new panel which uses American Sunpower cells is better than others in lower light levels.  That suits me fine, I’ll get better than I might expect 99% of the time and a tiny bit less 1% of the time.  Midsummer explained that mine is the first of a new batch they have just received and they hadn’t noticed the voltage increase.  Their website has now been amended accordingly and they’re sending me some much needed free cable and plugs as a recompense for my distress.

I think what I had overlooked is that the MPPT controller would manage the slightly mismatched voltages and make the best of it.

PS My blockbuster novel Jobs for the Boys is free again this week (Tue-_Sat) on Kindle  Cheap at half the price.  After that I’m hoping to reset it at 99p since a neighbour tells me that she always looks for the 99p books on Kindle.  Maybe that’s where I’ve been going wrong,  £1.15 was too up market. My cut will go down to 28p, but a million times 28p is OK by me.  I can’t wait to get rich.

Sunday, November 05, 2017

When is a tree not a tree? – CRT tells me

Tomorrow it’s back on with the blue volunteer sweatshirt and the black fleece and out on the towpath for CRT.  I have done very little for them this year, mainly because all the action seems to have been east of Paddington which I have decided is out of my reasonable journey time from home, but this time I have a chance to do something interesting along the dear old Slough Arm.

Using a special iPad app linked to GPS, we’ll be recording “woody growth” - trees, shrubs and saplings, growing between the towpath and the water, including that growing out of the “wash wall”, sometimes damaging the canal bank.  Apparently customer feedback had highlighted this as a problem so CRT made it a priority last winter and Fountains, the contractor, was asked to cut down any such growth. Inevitably some will have been missed, so that’s what we’re looking for, so any remaining can go on the job list for this winter.  Because the contractor is paid for trees by number and size to be cut, but by length of towpath affected by other growth, (e.g three trees, or ten metres of shrubs) we have to decide when a tree is a tree, or when it is a shrub or a sapling.  Any guesses?

Well the answer according to CRT is to estimate the diameter of the trunk  at 1.5 metres above the ground, for me that’s shoulder height.  Anything bigger than 3 inches is a tree. (yeah I know I have mixed metric and imperial, that’s me not them.)  Hmm I might take a bit of string with a knot at  9.4 inches as it might be easier to measure circumference sometimes. I know, I know, I’m an anorak. I hope I don’t find anything at exactly three inches, I might have a meltdown trying to decide.

Anything smaller is “other woody growth”. Then of course there are separate definitions for Small, Medium and Large trees, but I doubt we’ll be finding anything above Small.  “But when is woody growth woody growth”, I hear you ask?  Well stuff like brambles, saplings and shrubs, but not grasses, weeds, ferns and all that stuff.

So it all sounds like fun.  Anything we find will have its GPS location recorded and sent to CRT through the magic of telecomms.  Deep joy.

Changing the subject, you may remember my recent posts about choosing how to connect up a second solar panel.  Well I’ve bought one, and immediately come upon a problem which could have blown all of my research out of the water. You might need to know, so I tell you all later.