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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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.

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.