Alan Cuthbertson

alan@diydoubleglaze.com.au

DECEMBER 2015

Double Glaze Matters

Franciscus Henri’s contribution.

Firstly a very Merry Christmas to all and I hope you are not feeling over indulged to-

day. We have a fridge full of food and need to do some serious eating!.

The Paris conference was the best Christmas present that the world could get. I just hope it is as good as it sounds.

As an optimist it is wonderful that all the countries of the world could get together and agree that the problem is real and must be solved.

As a pessimist I worry that they are just

words. They plan to meet again in 5 years time and agree on how they will monitor progress and enforce goals. Then they will

meet five years later to see how they are going.

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This means in 10 years time we may find out that it isn’t working.

There are so many conflicting political and

financial issues that I really worry whether we will make progress. I am confident that renewable could make rapid and significant progress in replacing fossil fuels. However

our market based economies mean that as renewable get cheaper, established fossil fuels industries will just reduce their prices

to compete. Once you have established a mine or oil field, the incremental cost of extraction is not high.

So, don’t open new mines and bring in a price on carbon. It’s pretty simple really!

As a footnote, the Melbourne rally last month was apparently the world’s biggest. Congratulations to those who attended.

Par is & Chr is tmas

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DOUBLE GLAZE

MATTERS

My Arduino power monitor Display.

There is 525 watts flowing from the

panels and 130 watts from the grid.

The phase difference is 0 (6 on both) so

I am importing from the grid.

Beyond Batter ies

In my May newsletter I talked about methods other than batteries to store energy. While batteries such as the Teslar are grabbing the headlines, they are still a long way from every

day use.

In the New Year an 8kwh Teslar unit is to be offered in Australia for $12,000. Assuming you fully charge it each day and use it each night, you will save around 25 cents for each kwh, or $2.00 a day. That is 16 years to pay it off. It needs to drop by a factor of 3 to be cost effec-tive. The good news is that this is what hap-

pened to solar panels over the last 10 years.

There are other “batteries” that we may al-ready have. If you have a reverse cycle air conditioner, you can use it to heat the house during the day using power for 5 cents/kwh and avoid using the heater in the evening when it would cost 30 cents/kwh.

If you have a heat pump for you hot water, you can “over heat” it when you have excess

power. Normally you could heat it to 55 de-grees, but when you are supplying power back to the grid you could heat it to 75 degrees. The hot water tanks store around 300 litres. The heat needed to heat it an extra 20 degrees is around 6 kwh. This takes around 1.5 kwh of electricity. Effectively you have a 1.5 kwh bat-

tery that costs $3,000. Almost as cheap as a Teslar battery! If you already have a heat pump for hot water, you can use it as a free battery!

The main problem is that you need a manage-ment system that:

• Detects if you are exporting power to the grid

• Changes the target temperature on the heat

pump.

Over the last weeks I have made progress on building the management system! I have installed an Arduino based machine that uses two current loop detectors to measure the power flowing from

my solar panels and the power flowing from the grid. By detecting whether the two currents are in or out of phase I can tell whether I am exporting or importing power.

The accuracy isn’t brilliant. Probably within 50 watts for power under 200 watts and increasing to a 200 watt error at 2 kw, but that is good enough for my purposes.

A better way would be to use the ZigBee interface

direct to the meter, but that is beyond my pay grade.

I have also built an infrared detector/emitter and successfully “read” the signal from my TV control and then used it to turn on and off my TV. My family were not as impressed as I was, but it means in theory that I can control any air condi-tioner from my unit.

My main problem at the moment is getting the

power detector unit to talk to the air conditioner controller units over a wireless link. The standard Arduino system has proven unreliable. I have or-dered a “Raspberry Pi” base system which will do it, but it is rather expensive. It is based on an “open Source” solution, so if it works it may be possible to do it cheaper.

If anyone is interested in being involved in this

project, I would love to hear from you, especially if you have experience using ZigBee on an Ardu-ino .

My fellow Canberra Walker, June

Norman, protesting in Paris with the

Climate Guardians