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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Tags: default program
, different times
, dish washer
, electricity meter
, electricity meters
, external signal
, necessary infrastructure
, optional feature
, power consumption
, washing machine
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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Tags: change technology
, electrical heating
, good heat
, heat reservoir
, heating water
, hot water bottle
, phase change materials
, pressing iron
, production quantity
, storage place
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:
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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Tags: amount of money
, electrical installation
, good friend
, photovoltaic system
, physical constraints
, random person
, renovation project
, special offer
, typical calculation