Going solar

It looks like it’s going to happen this year – we’re going solar! It has been on my wish-list since 2008, so it’s time to do something about it. The decision to finally cover our roof with solar panels was the easy part – and now I’m overwhelmed with all kinds of questions!

Solar panels

Of course, I want the best there is in terms of quality, the amount of electricity they produce, power degradation caused by aging, guarantee (and all that within our budget of course..).

What brands should I look for, which ones should I avoid? The panel dimensions seem to differ a bit as well (lengths from 160 to 180 cm); which dimensions are optimal for our situation (orientation, available space)? How much room do I actually have to place solar panels? Should I buy mono- or poly-crystalline panels, or should I not even worry about that?


Again, which brands have a good reputation, have well documented monitoring capabilities.  And what’s this Optitrack Global Peak, do I need it? Or maybe all recent inverters have it built-in already?

These are all questions related to the hardware; but there are some other issues to resolve as well and not all are that easy to deal with.

Should I go all the way now or save some space (and money) for next year? And should I buy an inverter with more capacity than I really need, so that I can easily add more solar panels next year? Will this have a considerable impact on efficiency this year? What’s the best place to install the inverter? As close as possible to the solar panels sounds like the best thing to do, but that’s not so practical in our case.

Another thing to tackle is that we don’t have a crawlspace under our house, which makes it harder to easily hide cables; how difficult will it be to get cables from the inverter to where the connection to the utility grid will be made? I don’t really like cable ducts on the outer walls of our house; however, I like them even less inside! How much do our roofs suffer from shading caused by surrounding objects? What will this do to the solar panel output?

Oh my… all those questions, decisions to make, things to dive into… so I decided to first take one ‘easy’ decision: I will install our solar system myself (with a little help here and there). Mounting the panels on the roof, the cables from the panels to the inverter and to the mains distribution panel. That should all be not too complex for me, I guess.

I’ve been sketching, surfing, measuring, reading, searching, discussing during the last 3 weeks and I think I know a bit more now. For instance, in our case it looks like it’s better to give the solar panels a SW (South West) instead of a 100% South orientation, since the number of panels that can be placed on the roof in SW orientation is much higher; and those extra panels can easily (over-)compensate the efficiency loss caused by the SW orientation.

Another thing is that it looks like a good idea (efficiency-wise) to give the solar panels an angle of 30° inclination, but this will result in a very large distance between multiple arrays of panels, sometimes as much as 2.40 m! By using an angle of 20° this distance can be reduced drastically, which might give enough room for an additional array..

Portrait or Landscape, another thing I’ve been thinking about. With partly shaded panels the preferred orientation is landscape, cause (assuming that it’s the lower part of the panel being shaded) in portrait orientation the bypass-diodes can/will shutdown a complete panel instead of just a part of it.

Talking about shadow; how much shadow will the solar panels face? I really don’t know! I don’t spend that much time on our roofs… I do know where the sun rises and sets approximately, but never really paid attention to if, where and when we suffer from shadow – especially on the roofs.

To get some more grip on this I made a Google SketchUp Model and created 6 animations, for January 1st, March 1st, May, July, September and November. Just to give me some more insight on the amount of shadow. And now I know that (what a surprise) November till January are really shady months up there! Watch the 6 animations yourself here:


Well, it seems I’m still in a stage where trying to find an answer to a question brings up more questions than answers…

Gas consumption under the microscope

I’m not really satisfied with how our Central Heating is functioning. Not that we have technical problems, but the way our house is heated isn’t satisfactory anymore. Maybe it has to do with the floor heating we installed earlier this year; I don’t know for sure – I guess it does, but to make the right conclusions, I need more information.

For example, here’s the chart for the central heating of December 24th & 25th, where you can see at what times and for how long it’s heating the house:

Why is there such a big heating interval in the afternoons? What’s the most important factor, outside temperature or the amount of sunlight? (the latter is definitely of influence cause the living room has a window on the south, measuring 2 x 3 meters…)

Looking at the right side of the chart below, we see the temperature in the living room (the red line) rising to 21.7 °C without any heating (green = thermostat setback):

Free energy from the sun; that’s very nice, but not good for keeping the rest of the house warm.. 🙁

I really need to create some more insight on all of the factors that influence the behavior of the central heating system.

So that’s what I am doing right now. I’ve added some virtual devices to my Domotica system to calculate some additional values from all the sensors I have.

  1. Break down total gas usage into 2 parts: gas usage for CH (Central Heating) and for DHW (Domestic Hot Water). I can do this cause my Remeha Calenta tells me whether there is DHW demand or not. This should give me a clearer picture of the amount of gas used for heating; ‘noise’ by someone taking a bath or a shower will be filtered out.
  2. Average Outside Temperature per day. For this I compared measurements from the nearest KNMI weather station (12 km) with my own outside temperature sensor and didn’t see a need to collect the weather data from KNMI, saving me some additional work. I’m going to use my own sensor for this. This sensor is probably not located at the right height, it’s mounted to a wall of the garage etc. which will result in an offset, but it should be good enough to use.
  3. Average light intensity in the living room; I have a Lux sensor in the living room and I’m going to use this one to monitor the average amount of light there.

These values should give me a more detailed view of what is happening and how much the influence of both outside temperature and sunlight really is; I know they do, but not how much..

With this I want to be able to explain the behavior of the central heating and explain the gas usage that comes with it.

I started  a webpage to do just that. It’s not finished yet; more information will be added like the weighted average of the thermostat setback during a day, average temperatures in the ‘other’ rooms and things like that.

What I really want, is being able to control the temperature per room: the bedrooms, bathroom, my office and the living room. That’s a total of 6 rooms. Looking at how much sunlight influences the central heating, I need a way to deal with that influence; but how? I will probably need to control the amount of heat flowing through the floor heating based on the temperature in the living room, cause when another room is demanding heat, I don’t want heat pumped into the living room when it’s already warm enough!

And I probably also need to control the radiators in the other rooms to get the right temperatures over there, cause I have the feeling that too much heat is going to the living room right now, leaving too little for the other rooms. But first, that feeling has to become a conclusion before I can move forward!

All those adapters

It’s time to follow up on some energy saving tricks I know about for quite some time, but which I didn’t implement yet.

A couple of places in my house are crowded with power adapters. One of them is the meter cabinet. Over the last 5 years, the number of devices just kept on growing, and of course they all came with their own power adapter. And when you touch those adapters, you can feel they all produce heat. Some are really warm actually, and look quite old. And heat means inefficiency; so it was time to make a list and see if I can reduce the amount of power supplies. It looks better, and from what I’ve heard from others, this exercise can  result in a relatively substantial yet ‘easy’ way of saving energy. So let’s do it!

So what do we have in the meter cabinet:

  • an old POTS PBX;
  • Visonic Alarm system;
  • Siemens M20T GSM modem;
  • Synology NAS;
  • PLCBUS PLC1141 Interface;
  • ACT TI-213 X10/A10 Interface;
  • RFXCOM RFXMeter;
  • Sollae EZL-400;
  • D-Link 8-port 1Gbps switch;
  • Alphatronics Visonic receiver;
  • Fritz!Box WLAN 7170.

7 of these all have their own power adapter. But looking at the output voltages of these adapters, it comes down to 9V AC, 5V DC and 12V DC. So why not combine those 7 devices to 3 adapters? So I ordered 3 new adapters with a higher wattage that should be able to power those 7 devices.

Power Monitor

Power Monitor

Do I have any idea what I will gain in energy saving by doing this? No, not yet; but I’m going to use my good old Power Monitor PRO for that; I bought that thing at least 10 years ago I guess; I think you can remember those days, when energy saving was considered silly, a waste of time; who cares?? Well, I did 🙂 A lot has changed since then.

Lamp replaced by "DIY Ambilight"

LED strips

Even in full daylight and the LED strips @ 50%, this already looks VERY OK to me! Can’t wait till it’s dark outside..

After some small tests during the last couple of weeks, it was time to finish replacing a lamp near the TV with LED lighting. It’s still a big cable mess in the corner where the TV is located, but you can’t start cleaning up when you’re not finished, right? A lamp, holding 2 energy saving light bulbs, consuming 11W, has now been replaced by LED strips attached to the back of the TV. I call it my “DIY ambilight” project 🙂

The following components were used:

  • 1 x JeeNode v4;
  • 2 x MOSFET Plug;
  • 3 meters of warm white LED strip;
  • XBee series 2 module;
  • XBee breakout board;
  • 3.5 mm mono plugs;
  • 12V power supply.

And 3 x software; 1 for my Home Automation system, 1 for the JeeNode and 1 for the Touchscreen. The Pronto will follow soon.

From my Home Automation system i can control each of the 4 segments individually; i created a new device type and when i send a “L=30” command to this device, the LED strip on the left of the TV goes to 30%. When i send a “B=0“, the bottom LED strip goes to 0%. A “*=10” will result in all 4 LED strips to go to 10%.

The hardware (power supply, JeeNode, LED strips) is controlled by a PLCBUS appliance module, so when it’s time to go to bed, i don’t have to worry about additional standby power usage.

On the Touchscreen i added a popup form so i can change the settings of the LED strips:

TV LED control

Although I’m technically able to, i didn’t put 4 trackbar controls on this form to control each LED segment individually. The reason for that is that I don’t think it will ever be used by anyone else but myself. I think, in daily practice, these 4 LED strips will only be switched on and off, once a brightness level has been set that suits the ligthing in the rest of the living room.

The sketch that is running on the JeeNode is pretty straight forward, once you’ve seen Jean Claude Wipplers sketch to control RGB strips. I think it’s needless to say that without his hardware, software and sharing of knowledge, i would probably still be watching blinking LEDs… well, sort of 🙂

Well, anyway, here it is.

Curious about how the back side of the TV looks right now? Here you can see where the LED strips are attached to the back side of the TV and where i placed the 12V adapter and the enclosure that holds the MOSFET plugs, JeeNode and XBee.

Once i had it all (more or less) figured out, it took me 2 afternoons to go from a cardboard test setup to what it is now. Based on the response from wife and children, this is the best thing that has happened since the introduction of the touchscreen. Which I implemented 18 months ago… 😕 And what has happened to that $$$ Roomba???


Power consumption? The LED strips provide enough light @ 16%, resulting in a total of 2W power usage. Not bad!

Floor heating vs energy saving

Once we had decided that there would be a new marble floor at ground level, it was immediately clear that a floor heating would also be needed because for most of us the main trigger for turning up the heat, is cold feet. But what effect would this floor heating have on energy consumption?

After the decision for the new floor had been made, everything went very quickly and I actually had little time to devote to the issue of energy consumption. I didn’t really like the prospect of having another power consuming pump in our house… but then there is always a good tip from Pieter 🙂

Pump consuming at least 44W...

Pump consuming at least 44W ?? 🙁

Normally, a floor heating comes with a standard pump, in this case from the Grundfos brand, including a pump switch. This pump switch switches off the pump at times when there is no need for it to run and thus saves energy.

Floor heating unit with standard pump

Floor heating unit with standard pump

However, nowadays there is an alternative, namely the Grundfos Alpha2. This is a pump which significantly reduces energy consumption. At least, that’s what is being advertised; time will tell how much of this is true… The extra cost for this pump of EUR 190 should be recouped within 2-3 years; for me a good reason to let the standard pump be replaced by this Alpha2.

Grundfos Alpha2 using 7W

Grundfos Alpha2 using 7W

The most exciting feature of this pump is called AUTOADAPT, which means the capacity (=used energy) is automatically adjusted to the demand. In the above picture you see my Alpha2 consuming 7W while the central heating is on.

This week i was finally allowed to turn on the floor heating (hey, we’re in the middle of May! I shouldn’t have to do this!) and saw this pump use 7-8W of energy, which is much less then a conventional pump would use. How this pump (which has to be  used without a pump switch btw) performs compared to the combination of a standard pump including pump switch? Time and a energy meter will tell!

LED strip integrated in Domotica system

Now that the new floor is nearly finished, i can start working on some Home Automation related subjects again; the first was using LED strips in the kitchen.

LED strips

LED strips

In total 4 segments of LED strip are used; 2 near the floor at the plinths of the lower kitchen cabinets, 1 at the counter top and 1 on top of the upper kitchen cabinets.

Today i finished controlling all these LED strips individually.

I don’t have Ethernet in the kitchen, so i used the ZigBee approach (again :-)). I mounted a XBee on a Sparkfun XBee RS232 board and connected it to the Chromoflex RS232 RX input:

XBee and Chromoflex in a box

XBee and Chromoflex in a box

The XBee RS232 board is powered by the adapter that also powers the Chromoflex, so all i needed was a wall outlet for the Chromoflex adapter and the Chromoflex was “connected”.

Now it was time to add control functions to my Touchscreen application, running on my Asus TOP in the livingroom. I added a “LED” button on the floorplan, in the middle of the kitchen:

LED button on the floorplan

LED button on the floorplan

And i found a very cool Trackbar Control and created a new pop-up form with it, that appears when you push the “LED” button:

LED Trackbar

LED Trackbar

With this form i can control each LED segment individually. To minimize traffic, i used the same approach as i did earlier with controlling my thermostat; a timer event fires when the Trackbar value hasn’t changed for 1.5 seconds and sends the new value to my Domotica System by XMLRPC:

VB.Net code

That’s all there is to it. My Domotica system takes care of the rest e.g. building the Chromoflex packet based on the USP3 protocol, wrapping it in a XBee Transmit Request packet and sending it to the ZigBee coordinator. Home Automation is sooo cool 🙂

Predictable LED troubles

In november 2008 i replaced 2 conventional fluorescent tubes by a LED version. Thinking they would last a long, long time was very, very wrong… In october 2009, not even a year after i started using them, the first tube started acting strange; one of the three rows of a total of 342 LEDs wasn’t burning anymore. Next day, the second row of 114 LED’s stopped burning. Guess what happened the day after that… a rough calculation tells me this tube has done its job for 360 x 5 = 1800 hours. Multiplying by 10 doesn’t even come close to what is advertised!

So i called the supplier for replacement tubes.

LED tube

LED tube, "version 2"

He promised me he would send me 2 new tubes, although he warned me in advance that it could take some time.. OK, i wasn’t in a hurry for replacement cause one tube was still working. But in the 2nd week of January i called again  to ask why it took so long for my LED tubes to arrive? The result was a very interesting conversation and i was given a bit of insight on how the LED market is working nowadays.

For example, i was told that the supplier had experienced a huge amount of failing LED light products being returned, especially during the hot summer of 2009. Bad design led to massive overheating of LED tubes and other LED products, causing lots and lots of  malfunctions..

Another thing the supplier told me, is that they had stopped selling most of the brands and had now limited their product range to only the high end segment; only those (with an equally high price tag) products could possibly live up to the life expectations that are so strongly advertised. Between the lines, you could read that his business had been seriously threatened by all the problems they faced with LED products in 2009. Quite a story for a normal ‘consumer’ like me who likes to try out new products, technologies and gather experiences with those products.

In my opinion, LED is hugely overrated in specifications, lifetime expectation and savings. I’ve bought at least 10 LED bulbs in the past year of which 3 stopped working in their first days. That’s 25-30%! within a week.  Needless to say i have very big doubts about the quality of the current LED technology.

And what will happen when my newly placed LED tubes stop working again in, say, 6 years? Will those tubes be replaced again, at no charge? Guess not.

No, for me LED is a nice product for the manufacturers, who don’t fully control the process of producing a good LED product yet but don’t mind making big money with it already, letting the customers pay 80 Euro for a single LED tube and delivering garbage.

And for politicians, who are encouraging the use of LED to show off how ‘green’ they are, while believing the LED producers on their blue eyes regarding to the quality of LED products. I wonder how much of them are actually using LED products themselves.

Me? I’ve learned my lesson and will not buy any LED product until my box of spare energy saving lamps is completely empty.

New freezer: minus 440 kWh per year on power consumption

Yesterday our old and broken freezer was replaced by a new A++ class freezer, a Liebherr GP1466-22.

While hunting down the large power consumers in our house, i found out that our old freezer had a defective thermostat. It was constantly freezing, 24 hours a day! Something had to be done about that, since constantly cosuming 65-70W is way to much! Now that the new freezer has been working for 30 hours or so, i can see it has an average power usage of 16.5W. That’s 145 kWh per year, where the old freezer used 587 kWh. That’s another 440 kWh saved on a yearly basis…

Now i wonder how the manufacturer has come to the advertised 135 kWh…

Replacing Fluorescent (TL) tubes with LED version

While doing all kinds of things to reduce power usage in our house (very good to combine with Domotica), i realised it was time to do something about those fluorescent tubes in my office.
There are 2 lighting fittings above my head, each one of them having 2 (120 cm) fluorescent light tubes of 36W. That’s quite a lot of light, but also Watt.
First thing i did was reduce the amount of tubes to 2. This still gave me enough light; but still i wasn’t satisfied and was looking for a way to reduce power usage further.
So i started looking for a way to replace these TL tubes with a LED version. After searching some websites that have lots of information about LED lights (like www.olino.org), i found these tubes.

Power consumption of these tubes is 15W, and they can operate without a ballast. If you’ve ever felt how hot a ballast can become, you’ll understand what waste of energy this is.

I decided to buy 2 of these tubes and yesterday they arrived:

Because i have to modify the fittings a bit (removing the ballast and rearrange the wiring inside), i have to wait untill next weekend before i can start replacing the tubes with their LED version since that’s the first time i’ll be home during daytime…

I hope that replacing the TL tubes with LED tubes will also reduce the noise i am experiencing from the TL tubes. That would be a nice advantage; this will save me a few X10 noise filters. And i’ll get rid of the sometimes very annoying time the TL tubes need to start giving light.

We’ll see what happens.

Drill down charts for Gas usage

I purchased Chartdirector recently. Not being satisfied with the charting software i used so far, i decided to go for this product after trying several others. I think i made the right choice 🙂

While moving to Chartdirector, i read all kinds of stuff about clickable charts, a feature i couldn’t use before. This could be a really good opportunity to try and do something about not being able to keep track of detailed information on data that was getting “old”. So i decided to create a page with 4 clickable charts to get from a year-based chart down to an hour-based chart:

Clicking on one of the bars above will instantly update a chart that displays the data for all the months in the selected year.

Clicking on one of the bars of the chart above, will instantly update a chart that displays the data for all the days in the selected month.

Clicking on one of the bars above will instantly update a chart that displays the data for all the hours in the selected day.

And that is where it ends, gas usage information is stored on an hourly basis, so here you are at the level at which the information is stored, just with 3 clicks…