Another ‘Brown trouser’ Sunday :-(

Before I get ‘all glum’ reflecting on today’s lack of progress I’ll ‘rewind’ back to Saturday, which was far more productive.

The first job being to take over 600lts of kerosene to the Schoolhouse to keep pace with our 100lt per week consumption!!!  I don’t feel too bad about it though, some of the guests that rent the place can get through more than that in the summer!!

Showers of hail and snow on the forecast had me escorting the postie to work in Phoebe.

The road wasn’t bad and had been gritted but more snow was supposed to arriving over the weekend so she decided to leave the post van in the village and use Phoebe and her 4WD. I returned in the Almera and continued transporting the barrels over to Torran one at a time on what turned out to be a really sunny day.

The Tri Star MPPT45

Relying on gravity to empty the 208lt barrels is a slow process but it fitted in well with my other project for the day.

The ‘Old Schoolhouse’ has a very reliable ‘off grid’ system based on 1260w of solar and a hydro turbine capable of supplying around 750w at this time of year. We’ve had absolutely tons of power and the Studer SW2324 inverter has supplied it all seamlessly. However during the summer the burn reduces to a trickle and the hydro is down to just a few watts. More solar would obviously be the answer but all the available southerly facing roof on the ‘boot room’ is taken up by the 3 x 250w and 6 x 85w modules.

These nine panels currently charge the batteries via a PWM (pulsed width modulation) controller, which to be honest is my preferred option. PWM controllers like the Tri Star TS45 and Xantrex C40 are relatively cheap and very reliable, however there is a more efficient way. Maximum Power Point Tracking is the method used by grid tied inverters and it can produce an improvement of up to 20% in typical Scottish sunshine In other words it’s more efficient in marginal conditions.

I’m not really a fan of MPPT controllers for battery charging as they are very expensive and it’s normally more cost effective to just fit more panels. However, when my good friend Leslie Bryan out in rural Normandy   http://www.echorenovate.com/  had one for sale at a very reasonable price and I knew it had been abused. Leslie is very ‘hands on’ with everything and is in the process of going ‘semi off grid’ on his large rural property that’s currently undergoing a transformation. An engineer and ‘horologist’ to trade Leslie can turn his hand to anything and plans to turn his place into a centre of ‘sustainable living’ running courses on green building and renewable energy. Indeed, amongst other things he’s produced an excellent booklet on how to make ‘cost effective solar trackers’ http://www.echorenovate.com/new-book—make-a-solar-tracker.php

 

So, whilst the barrels were slowly emptying I set about replacing the PWM controller with the MPPT one,

turning off the ‘Harris Hydro’ turbine first so I could flush out the pipe and reduce the input to the batteries. The hydro turbine doesn’t use the MPPT controller but I was wanting to deplete the batteries a little for my next job.

 

The MPPT controller is slightly larger but the ‘knockouts’ and bottom four screw holes are in the same place. The cables to the batteries and panels are not quite the same and I had lengthen one but all the ‘dip switches’ for the settings serve the same function, so I just had to alter those. Leslie’s ‘semi off grid’ setup, like mine uses 48v batteries.

With that in position and working I then set about improving the immersion element diversion system. The controller on the right diverts the first lot of  excess power to a 1kW heater in the thermal store. This is set at half a volt below the MPPT controller so that once the immersion is ‘maxed out’ the battery voltage rises and then the second controller ‘throttles’ the panels. It was Hugh Piggott of http://scoraigwind.co.uk/ that suggested this method and supplied all the kit for this and my system. Along with the gear comes the best advice and this configuration above works really, really well.

With the power to the heater turned off I went into the ‘boiler room’ and rewired it with a dedicated isolator.

 

That concentric hybrid cable with an aluminium core and copper sheath is a bit of a nightmare to work with, but with a 25mm square copper equivalent impedance it’s great for low voltage DC applications like this.

Sure enough

with the hydro now ‘running clean’ I turned everything back on and as soon as the batteries were ‘topped up’

the first controller started diverting and the immersion started its characteristic PWM buzz.

Party on

It was an early finish for we were all off to ‘number 3’ for a birthday celebration,

a pure vegetarian feast of lasagne, lentils, cheese, olives and salad. All washed down with loads of red wine and home made ‘MkII Drambuie’.

Considering the overindulgence I was surprisingly chirpy this morning, though I have to say that I foresaw the hangover so left the quad at Arnish last night. The walk home at 9:30ish last night and the walk back at 7:30 this morning going a long way towards ‘restoring normality’.

Not a good day

Just like last Sunday, things did not go smoothly today and it was nothing to do with the lentils. The gale arrived bang on time and from the south, just as predicted, the turbine was pure ‘belting it out’ and I’d a big broad smile on my face.

A full 3.3kW and at one time it was over 4kW!!! However, that didn’t last, in a lull the voltage dropped below the ‘cut in’ threshold of 246v (the lowest this inverter will accept) and then along came the wind and took it over 600v before it had chance to connect again.

Once again I connected the hydro turbine DC to the Windy Boy inverter and brought out the laptop and once more I commenced a day of messing about with the settings.

It worked absolutely great in ‘MPPT mode’ but for some reason when in that mode it kept dropping out due to an ‘AC disturbance’ which I never got to the bottom of and there seems to be a 180second delay to reconnect, which I could not reduce. Tweaking about with the settings and using the hydro DC as a power source I managed to get it functioning again but I’m not really very happy.

This SMA software is pretty rubbish and the next thing that happened was that my laptop crashed so I spent pretty much all afternoon trying to sort that out. I figured that if I could load up the turbine a bit more it would be less prone to going over voltage.

However, I had even less luck with the ‘Windy Boy Setup Tool’ than I did with the ‘Sunny Data Control’ so gave up and tidied up the shed.

   

Sure, it might not be working very well but it does look neat I really must stop working on the Sabbath, every time I do something on Sunday it goes pear shaped, so I’m just going to have a large dram of ‘Balvenie Double Wood’ single malt and try and get some sleep.

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Three quarter inch ‘chuckies’ :-)

I think my output is directly proportional to the amount of wine I drink, hence the lack of posting, I’ve been resting my liver. Well, I thought I’d give it a little exercise tonight, thanks to a nice bottle of Villa Vinci, Montepulciano  ‘D’ Abrruzzo my mum gave me on Monday. Not that I’ve actually tasted it yet but my mother has never bought me a bottle of dud wine yet, after all, what are mums for

Anyway, having made a start on laying down the ‘chuckies’ in front of the barn I got a little obsessed with it, as it made such a difference.  The ground outside is mainly compacted rock with a little clay in between so it’s as hard as iron with little scope for weeds but it’s got one or two permanent puddles due to water running off the bank. The water isn’t deep but it’s invariably just outside the door of where you park and the ‘wee dug’ constantly covers the interior of our vehicles with mud.

As there had been snow and possibly ice forecast for the  Monday night I decided to escort the postie and her van south then continue onwards to the Sconser quarry for more ‘three quarter inch chuckies’ for the barn.

As it happened the forecast was wrong and there was sign of neither snow nor ice, which was just as well for the Ford Transit Connect that wifey drives for Royal Mail is pretty useless in either.

Well, that was a mistake

Hmmm, Friday night now, the wine was so good that I had a glass and fell asleep, trouble is there’s still some left so perhaps I’ll do the same tonight.

Anyway, I’ll have a go.

I arrived at the quarry as preparations were well underway for a few blasts that would displace almost a quarter of a million tons of rock from the hillside.

That ruck is carrying the explosives in a three part liquid form, ammonium nitrate, fuel oil and something else, individually quite harmless but they’re mixed by the truck and poured down the holes. All they need then is the detonator to set off a very large bang

As you can see, things have ‘moved on’

 

There was some serious machinery on hand to start moving it after the blasts and I must get a hard hat and hi viz vest for the ‘wee dug’. Boy, I really would love a shot in that 38 ton digger, I could do some serious damage with that on the croft!

Whilst not in the same league as a 38ton Volvo digger this lovely ten year old DAF of ‘A Macleod Haulage’ from Strollamus is quite a machine too.

 

I forgot to weigh myself before and after the shave, but here’s what a Land Rover, trailer and wee dug weigh in at. Also, there cannot be many quarries with a public road through the middle of them, and hey what a view from the office. Having said that the last office got blown over and landed on the mangers van, with him in it!!! The office that is and not the van, Sconser really is a very windy spot, needless to say the new office is well attached to Scotland now.

 

 

After two tons of the chips was expertly and very accurately dropped in Lachie’s trailer I headed home with all my hair. I was hoping to get a hair cut whilst I was there but it just didn’t happen

 

As the ground at this end was not quite as solid and rocky as the first area we did we put some Teram fabric down. It probably wasn’t really required but I had a good piece that the wind had unravelled off a roll.

Over a couple of days we put down eight tons which really did make a huge difference to the area.

A couple of days was spent looking over Phoebe for the MOT and doing a few minor repairs. Nothing serious and she passed today with just a couple of ‘advisories’ that I’ll deal with in due course.

 

The last few days have been ideal ‘renewable weather’ with plenty of wind for the wind turbine, water for the hydro turbine and sunshine for the solar panels.

  

Over a 70 hour period the 2.5kW Proven/Kingspan http://www.kingspanwind.com/products/kw3/   turbine came out on top with 57kWh generated, the 800w Powerspout http://www.powerspout.com/ a close second at 54kWh and the 4.75kW solar array a paltry 15kWh. However it’s only February and as the wind drops and the days lengthen these figures will inevitably change dramatically in favour of the solar over wind whilst the hydro remains stable. The meter from the solar only actually monitors 2.2kW of the array but it’s a fair assumption just to double the recorded 7.5kWh. So, all in all quite good with an average of over 42kWh per day, now that is pretty good for an investment of well under £18k, sure the batteries may need replacing in 10 to 15 years but offset that against no electricity bills, standing charge, heating bills and most important of all a reliable supply. I have had less power cuts in 25 years than Raasay gets in your average winter and mine generally last a few minutes whilst I go out an reset something.

Of course it’s not quite as simple as that, I do have to maintain stuff, have spent years online researching and I have had the occasional ‘brown trouser moment’ but it is supremely satisfying to make your electricity from the elements.

 

I also have a nice warm shed that seems to attract toads thanks to all the ‘dump loads’ I fitted.

I have been reconfiguring my 2 x 3kW loads and 1 x 1.5kW to 3 x 2.5kW to better match my 45amp controllers.

Instead of having two of these in parallel to give me 3kW

1760858 

TE CONNECTIVITY / CGS  TE1500B2R2J  RESISTOR, 1500W, 2R2

I now have one of those and one of these

1760837

TE CONNECTIVITY / CGS TE750B4R7J RESISTOR, 750W, 4R7

which gives me 2.25kW

Choosing a resistor as a dump load

Rather than me making a complete hash of ‘Ohm’s law’ and explaining it all wrong I’ll just copy an excerpt from Hugh Piggott’s blog  http://scoraigwind.co.uk/

Using a high power resistor as a dump load

When choosing a dump load for your charge controller, you need to find heater or heaters that will:

• Be able to dump the maximum current your combined wind and solar systems will throw at it at once.
• Not draw more current than the charge controller is able to handle. (Which is the number in the name of the controller – e.g. C40 can handle 40 amps maximum.)

A neat solution to finding a dump load for a charge controller is to use a big wire wound resistor that you can buy from an electronic component supplier.  Look for ones with low resistance and high power rating.  There are not very many to choose from, and their stock is always changing.

The resistor has two important numbers associated with it:  resistance and power rating.  Resistance determines how much current it will dump in your system and the power rating is a guide to the maximum safe wattage it can burn off without over-heating.

When choosing a resistor/heater for a charge controller we need to start by considering the system voltage.  Say it’s a 12 volt system then the heater needs to be safe up to 15 volts.  (Whereas 24 and 48 volt systems can go up to 30 and 60 volts.)

Use Ohm’s Law to find the current the heater will draw at this voltage (if the controller turns it on fully).  For example if the resistance is 1 ohm (written 1R or 1Ω) then Ohm’s Law says:

Current = voltage/resistance = 15/1 = 15 amps.

Next find the power it will have to dissipate (as heat).

Power = voltage x current = 15 x 15 = 225 Watts.

In reality these resistors can take some overload (and the controller is unlikely to need to operate them continuously) so you can get away with a well ventilated 200 watt resistor, although my favourite is 300 watts.  This makes a good building block for a dump load system.  You can add more in parallel to dump more current (up to 3 in parallel for a Tristar 45-amp controller) and you can add more in series to go to higher system voltages.

Full article here http://scoraigwind.co.uk/using-a-high-power-resistor-as-a-dump-load/ and much, much more.

Well there was more, much more, I went to Brochel and collected 1000lts of heating oil, laid some drains to take water away from my lovely ‘chuckies’ and laid some cable in the new house.

 

Actually that’s a bit of a ‘porky’ I got my son to clamber into the rafters and lay the 7 core cable then fasten it in position whilst I passed him the tools. This is just some extra cabling for a voltmeter, generator start facility and anything else I can think of, better to lay it now and have spare cores than think of it later.

 

The concrete is curing nicely with just a few pale dots caused by condensation drips from the joist hanger brackets, which will only serve to add character to the polished floor.