Intel­li­gent elec­tric­i­ty meters? More ben­e­fi­cial things exist (but need improve­ment).

In Ger­many you need to install an intel­li­gent elec­tric­i­ty meter if you make larg­er changes to the elec­tric­i­ty instal­la­tion in your house (or if you build a new one). At first this sounds inter­est­ing. If you look clos­er, you need to decide if you want to laugh or to cry.

Such an intel­li­gent elec­tric­i­ty meter is able to dis­play the cur­rent pow­er con­sump­tion in a dig­i­tal dis­play (if the pow­er con­sump­tion stays the same, you can test with this how much pow­er a spe­cif­ic device needs). It is also able to attribute the pow­er con­sump­tion to dif­fer­ent times of the day. An option­al fea­ture (here in Ger­many) is the pos­si­bil­i­ty to trans­fer cap­tured data to the pow­er com­pa­ny. It is not required that the home-owner is able to see all or even any data from an intel­li­gent elec­tric­i­ty meter.

The promis­es are, that with such a device peo­ple could pay less mon­ey by using the wash­ing machine or the dish wash­er or sim­i­lar devices dur­ing times when not much peo­ple want to use ener­gy.

So far so good, but…

  • My wash­ing machine or dish wash­er are about 1 – 3 years old. We did not buy the cheap­est ones, but they do not offer to start the wash­ing upon input from an exter­nal sig­nal or just by acti­vat­ing the pow­er (if they lose pow­er, the cho­sen wash­ing pro­gram is reset to the default pro­gram). Am I sup­posed to buy a new one?
  • The pow­er con­sump­tion of all the nec­es­sary infra­struc­ture (dig­i­tal stuff in the elec­tric­i­ty meter, net­work con­nec­tion to the pow­er com­pa­ny) is not zero, and it is the own­er who has to pay for this.
  • When every­one is wash­ing when not much peo­ple want to use ener­gy, a lot of peo­ple want to use ener­gy in such moments. It may still help a bit the pow­er com­pa­nies because they do not have to gen­er­ate pow­er (and have expens­es because of this) which is not used, but I doubt the con­sumer will get a big reduc­tion then.
  • The dura­tion of such power-surplus times with a reduced price may not last dur­ing the com­plete time a wash­ing machine needs. It may be even the case that a high-price time slot may get acti­vat­ed short­ly after (if this is done by (mali­cious) intent or not is not even rel­e­vant, as the con­sumer can not do some­thing about it as he is prob­a­bly sleep­ing when this hap­pens in the night).
  • The pow­er com­pa­ny may be able to get a detailed trace of what hap­pens in a house (the own­ers are get­ting up at 11am, only take a show­er every two weeks, have prob­a­bly a big plas­ma TV which runs all the day, …).
  • I doubt the device is free of secu­ri­ty holes or pro­tect­ed enough against eaves­drop­ping (with all the pro­fil­ing impli­ca­tions, or pos­si­bil­i­ties to manip­u­late the data (pos­i­tive­ly or neg­a­tive­ly) direct­ly in the device before trans­mis­sion to the pow­er com­pa­ny).
  • I do not think the most intel­li­gent and consumer-friendly devices will come with enough sta­tis­tics or access-possibilities to real­ly sat­is­fy the con­sumers.

More inter­est­ing would oth­er things which could help cut costs. For exam­ple small low-power net­worked sen­sors which detect if a window/door is open, the tem­per­a­ture in a room, the out­side tem­per­a­ture, the sun­light inten­si­ty and so on. Togeth­er with some actu­a­tors like for exam­ple to close the win­dow, close the shut­ter, change the heat­ing, turn off lamps and so on, it would pro­vide much more imme­di­ate ben­e­fit. In a new build­ing, the net­work could be wired, but in an old build­ing the sen­sors need to be wire­less and battery-powered.

A pos­si­ble solu­tion could be done via blue­tooth v3 in a mesh net­work (yes, if it is not open source, I would also be scep­ti­cal if the com­pa­ny which pro­duces this has enough knowl­edge to make it secure), polled by a cen­tral sta­tion which could put the sen­sors in silent stand­by to reduce the amount of radio pol­lu­tion and increase bat­tery life­time. If some of the sen­sors and actu­a­tors are con­nect­ed (e.g. room tem­per­a­ture and heat­ing actu­a­tor plus a clock), you could even let it run in autonomous mode (time based heat­ing to a spe­cif­ic tem­per­a­ture) and only need to con­nect to it if there is a spe­cif­ic need. Such a sit­u­a­tion could be that the win­dow sen­sor detects an open win­dow, so the heat­ing can be turned off. Or maybe the sun­light inten­si­ty sen­sor detects (or the base sta­tion esti­mates) an intensity-rise of the sun­light, so the heat­ing could be reduced in advance.

Some­thing like this would give imme­di­ate ben­e­fit (in com­fort) to those who install it, and in a long-term view it would/could cut the costs down a bit.

I am aware of some wire­less sensors/actuators, but they are rel­a­tive­ly expen­sive, the radio pol­lu­tion (and type) is unknown to me, and the pro­to­col is not open, so I do not know if it is secure and how to improve things I do not like.

Any­one with enough hard­ware knowl­edge and open source/hardware spir­it out there to pro­duce a mod­u­lar base for sensors/actuators (blue­tooth + I/O for sensros/actuators/pc-connection + con­trol­er)?

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Weath­er sta­tion read­out with FreeB­SD

A while ago a wind tur­bine was installed not far away from my place. It is far enough to not dis­turb us, and it is near enough to notice that it turns a lot (IIRC I have seen it only once not turn­ing).

This trig­gered a ques­tion. How much ener­gy would such a device (small­er of course) pro­duce at my place?

The answer depends upon sev­er­al fac­tors. The wind speed, the wind direc­tion and the wind-speed-to-power-output curve of the device. If you do not take a device which rotates around the hor­i­zon­tal axis but the ver­ti­cal axis, the wind direc­tion can be tak­en out of the ques­tion (prob­a­bly not com­plete­ly, but to answer my ques­tion this sim­pli­fi­ca­tion should be ok). The output-power curve depends upon the device, and I hope it is easy to get it from the ven­dors. The remain­ing open ques­tion it the wind speed at my place. Is there enough wind with enough speed?

To answer this ques­tion I bought a weath­er sta­tion with an anemome­ter (wind speed sen­sor). I searched a lit­tle bit until I decid­ed to buy a spe­cif­ic one (actu­al­ly I bought three of them, some cowork­ers got inter­est­ed too but they found only much more expen­sive ones, so soon there will be three more weath­er sta­tions in use in Bel­gium, France and Ger­many). The main point is, I can con­nect it to an USB port of a PC and there is some soft­ware for Lin­ux to read out the data. It also comes with some oth­er outdoor-sensors (tem­per­a­ture, rain, wind direc­tion, humid­i­ty, …) and an indoor-control-unit with some inter­nal sen­sors (tem­per­a­ture, humid­i­ty). The user inter­face is main­ly the touch­screen of the control-unit. There is also some Win­dows soft­ware, which is need­ed to pro­gram the inter­val in which the mea­sure­ments are tak­en and saved in the control-unit.

It seems the weath­er sta­tion is pro­duced by Fine Off­set Elec­tron­ics Co.,Ltd and sold with­in dif­fer­ent brands in dif­fer­ent loca­tions. The Lin­ux soft­ware can read all of them, as the ven­dor and prod­uct IDs are not changed.

Port­ing the soft­ware was easy, it uses libusb and I just had to cor­rect a lit­tle prob­lem for the non-portable func­tions which are used (I asked about them on usb@ and the response was that they just got imple­ment­ed upon my request and will be com­mit­ted to HEAD soon). I made a lit­tle patch for the soft­ware to only use them when avail­able (if you have not loaded the USB HID dri­ver, you do not need to care about them) and com­mit­ted it to the Ports Col­lec­tion as astro/fowsr.

Now I just need to attach the out­side sen­sors at the place where I would put the ver­ti­cal axis wind tur­bine, install some toolk­it which takes a series of mea­sure­ments and dis­plays them as a nice graph (while keep­ing all data val­ues) and write some glue code to feed the out­put of fowsr to it. After a year I can then cal­cu­late how much pow­er a giv­en wind tur­bine would have pro­duced dur­ing the year and cal­cu­late the return of invest­ment for it.

The Lin­ux soft­ware also ref­er­ences sev­er­al weath­er sites, for some of them you can get even an iGoogle wid­get so that you can view the data from wher­ev­er you want (as long as you have a suit­able inter­net con­nec­tion). I think this is also some­thing I will have a look at lat­er.

Note to users in Europe, the device also comes with a DCF77 receiv­er. As the time is dis­trib­uted in UTC+1 (or +2, depend­ing on the day­light sav­ing time), you should adjust the time­zone set­ting accord­ing­ly to this, not to plain UTC (so for me the time­zone should be ‘0’ for the same time­zone).

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No good heat reser­voir avail­able?

I was search­ing for a good heat reser­voir. Unfor­tu­nate­ly it seems that all on the marked are far from state of the art (they are prob­a­bly in their class, but see below).

Most of the devices use water to store the ener­gy. I found one (in Europe/Germany) which is using phase change tech­nol­o­gy instead of water to store more heat in the same stor­age place (but you need to ask how much it costs and how long they need to deliv­er, which prob­a­bly means that it is a lot more expen­sive (part­ly due to lim­it­ed amount of pro­duc­tion quan­ti­ty) than water based heat reser­voirs). I have read a lot about phase change mate­ri­als (PCM), and it seems there are dif­fer­ent kinds of sil­i­ca or wax (or oth­er mate­ri­als) which are bet­ter suit­ed to store heat ener­gy, but the only mass-market tech­nol­o­gy seems to be water based ones.

This looks strange to me. When I look at his­to­ry, oth­er mate­ri­als than water where already used a lot in the past (e.g. stones where heat­ed and then they were used in a press­ing iron or as some­thing which is replaced now by a hot-water bot­tle or an elec­tri­cal heat­ing cush­ion in the bed; yes, all this does not involve a change in the phys­i­cal state of the mate­r­i­al, but the point is that oth­er mate­ri­als than water where already used in the past), so I do not under­stand what is pre­vent­ing to let PCM based heat reser­voirs going main­stream.

Except for choos­ing the right PCM and obtain­ing it, it does not look hard to build such a heat reser­voir. You can add a heat-exchanger in the bot­tom and feed solar-power there for long-term heat­ing the PCM, anoth­er heat-exchanger at the top to heat the use-water and/or heating-water from the heat stored in the PCM, and a 3rd heat-exchanger (placed at the top too) which you con­nect to your central-heating if you need a lit­tle bit of quick short-term heat­ing of the PCM. I do not know if you need to add some  heat-layers (e.g. by putting a big cheat of a non-PCM mate­r­i­al between the long-term heat­ing part and the short-term heat­ing part), but  it should be easy to test if some­thing like this is ben­e­fi­cial or not. If you have a fire­place which you want to con­nect to the long-term heat­ing of the PCM, it may also be ben­e­fi­cial to have a 4th heat-exchanger togeth­er with the solar-one, but maybe there is anoth­er solu­tion to do this with the 3‑heat-exchangers-setup (I have not inves­ti­gat­ed this pos­si­bil­i­ty at all).

If some­one knows some inter­est­ing prod­ucts in Europe or has some help­ful infor­ma­tion (any­thing which can be inte­grat­ed into exist­ing heat­ing sys­tems with­out much ren­o­va­tion of a lot of rooms), please write a com­ment.

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Pho­to­volta­ic from the bank (no real ben­e­fit for me)

A while ago I got a mail from my bank. They offer to fund a pho­to­volta­ic sys­tem on my house with a spe­cial offer. They give a cred­it upto a spe­cif­ic amount if I use it to install a pho­to­volta­ic sys­tem, and to pay it back I just have to give them the com­plete amount of mon­ey which I get from the pow­er com­pa­ny when the pho­to­volta­ic sys­tem is pro­duc­ing pow­er (the state requires the pow­er com­pa­ny to pay a spe­cif­ic amount of mon­ey – fixed dur­ing 20 years – for each kW/h). They also offer that a spe­cial­ist vis­its me to explain the pho­to­volta­ic stuff and cal­cu­late if all the phys­i­cal con­straints for such an instal­la­tion are OK.

At first this sounds nice, but I do not trust the words of some ran­dom per­son which wants to get mon­ey from me. So I had a deep­er look at it.

The roof of my house is still OK, but in some years (maybe 3 – 5) it has to be changed (at least part­ly). The roof  is already 30 years old, so this is OK. If I would install a pho­to­volta­ic sys­tem now, it would have to be removed and rein­stalled when the roof is changed. If the sys­tem is financed by the bank, this has to be done by an offi­cial spe­cial­ist (instead of let­ting a good friend with expe­ri­ence doing it in exchange of my work­force for some ren­o­va­tion project at his house). This means it would be cheap­er if I change the roof before the pho­to­volta­ic sys­tem is installed. I do not have the mon­ey to do this com­plete­ly out of my pock­et, so the bank has to finance this.

Let­ting the cost of the roof aside (which has to be done “soon” any­way), the inter­est­ing part now is what do I get when the bank is com­plete­ly financ­ing the pho­to­volta­ic sys­tem (maybe parts of the elec­tri­cal instal­la­tion need to get updat­ed, as they are 30 years old too). I have to take into account tax­es, what needs to be paid back to the bank, what I have to pay for the pow­er, and what I have when every­thing is paid back.

If the pho­to­volta­ic sys­tem is financed com­plete­ly by the bank, the typ­i­cal cal­cu­la­tion is that it takes about 20 years to pay back every­thing. This assumes I only give to the bank the amount of mon­ey I get from the pow­er com­pa­ny for the pow­er of the pho­to­volta­ic sys­tem. So basi­cal­ly the pho­to­volta­ic sys­tem pays itself. This sounds great, the prob­lem is that a rough esti­ma­tion of the life­time of a pho­to­volta­ic sys­tem is 20 years (and after 10 years you may have to change the AC con­vert­er). The war­ran­ty on pho­to­volta­ic ele­ments here is 2 years, so far I have not seen any offer where they extend it much (some­how it is hard to find some good pages for pri­vate cus­tomers, most of the pages I see are either light on info, or tar­get com­mer­cial cus­tomers). This is not even remote­ly in the range of 20 years. So after it paid back itself to the bank, it may be bro­ken. And dur­ing those 20 years, I still have to pay my com­plete pow­er bill.

There is also a tax point of view to take into account. Luck­i­ly a friend of my sis­ter is doing some tax con­sult­ing for pri­vate tax issues. The tax stuff involved here is about com­pa­ny tax­es (you are required to open a com­pa­ny when you install a pho­to­volta­ic sys­tem here). This is not spe­cial­ly in the area where she is work­ing in, but I assumed she should know enough about the basics, that I can get at least an overview. I got even more than that. When I talked to her about it, she told me they cal­cu­lat­ed a sim­i­lar offer for their house recent­ly. She assumed a pho­to­volta­ic instal­la­tion of 20 T€ and that the bank is financ­ing it com­plete­ly. The roof of their house does not have the same char­ac­ter­is­tics than my house, but as the pho­to­volta­ic spe­cial­ists cal­cu­late with rough peak sun­shine hours any­way, it gives me a rough overview. The good part is, that you do not lose mon­ey this way, but you have to pay the tax direct­ly (even if I give all the mon­ey from the pow­er com­pa­ny to the bank), you start to earn mon­ey near the end of the 20 years.

Accord­ing to her cal­cu­la­tions you will have earned 6 T€ after 20 years, when the pho­to­volta­ic sys­tem paid itself back to the bank and you had to pay the tax­es each month/year/whatever. This assumes that the peak sun­shine hours are not get­ting worse, and that the effi­cien­cy of the pho­to­volta­ic sys­tem stays at rough­ly the same lev­el dur­ing the 20 years. Now let us cal­cu­late the amount of mon­ey per month and per year you gain when you do this:

6000/20 = 300 €/year

300/12 = 25 €/month

So for 25 €/month I have to invest my time into tak­ing care about the tax stuff, have to take care about the pho­to­volta­ic sys­tem (clean­ing, and man­age­ment stuff in case some­thing breaks because of bad weath­er or nor­mal usage), have to pay extra mon­ey when some­thing has to be done to the roof, and so on. And when every­thing is fin­ished after 20 years, the pho­to­volta­ic sys­tem may be fin­ished too (and the rate of mon­ey the pow­er com­pa­ny has to pay for each kW/h then is not known, in case the sys­tem still works good then). If it is in a state where I have to remove or replace it, I also have to pay the cost of remov­ing it. And I need to get togeth­er enough mon­ey to get a new roof now.

Now this offer does not sound so good any­more (remem­ber, I also have to pay the pow­er I con­sume dur­ing this time). To me it looks like only the bank and the com­pa­ny installing the sys­tem will ben­e­fit from it, and I have to take care about all the unpleas­ant things.

There is for sure an eco­log­i­cal aspect to think about here. It sounds great to pro­duce green ener­gy (I do not know how much CO2 is pro­duced dur­ing the pro­duc­tion of the pho­to­volta­ic sys­tem, and if it will pro­duce enough ener­gy to com­pen­sate this), and I would do it direct­ly if I would see a sane return of invest­ment, but this offer does not look sane in my cur­rent sit­u­a­tion.

It seems I have to wait until the prices go down more (and I have some spare mon­ey to invest with­out the need for a bank). Recent­ly I have read that the expec­ta­tion is that in about 3 – 5 years the tech­nol­o­gy to print pho­to­volta­ic cells can be pro­duc­tion ready, which could reduce the price to a tenth of what a pho­to­volta­ic cell costs ATM. Invest­ing 20 – 30 T€ is not some­thing I would do from one day to anoth­er, 4 – 5 T€ for a sim­i­lar instal­la­tion sounds more easy to agree to.

While I am at it: so far I only see pho­to­volta­ic info regard­ing the peak pow­er a cell can gen­er­ate. To me this does not look inter­est­ing. The peak pow­er will be gen­er­at­ed most of the time in sum­mer (direct sun­light, no clouds, long sun­light times), but in the sum­mer the con­sump­tion of pow­er is less than in win­ter (less light to use, more time spend out­side the house so less time in front of a TV, more BBQ so less cook­ing in the kitchen, …). More inter­est­ing to me would be a good pow­er gen­er­a­tion in less than opti­mal sit­u­a­tions like in win­ter when it is cloudy (but it is prob­a­bly hard to come up with an use­ful val­ue, as the aver­age for “less than opti­mal” varies from loca­tion to loca­tion). I have seen a report about water heat­ing (attached to the cen­tral heat­ing) with solar ener­gy, where a sys­tem is used which has a low­er peak pow­er, but a bet­ter pow­er out­put in less than opti­mal weath­er con­di­tions (round col­lec­tors where used instead of flat pan­els). So the­o­ret­i­cal­ly there is the pos­si­bil­i­ty to get more pow­er out in not so good con­di­tions, but so far I did not find any infor­ma­tion if it is tech­ni­cal­ly pos­si­ble ATM to opti­mize pho­to­volta­ic cells to such sit­u­a­tions, and if it is if there are some cells avail­able for a sane price.

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