ᐅ Photovoltaic System: Self-Consumption Rate with Battery Storage and Additional Questions
Created on: 27 Nov 2015 13:23
T
T21150
Dear forum members,
At the beginning of 2016, I will be retrofitting my house with a photovoltaic system. It will have an east/west orientation with about 3.4 kWp per roof side.
The system will include an inverter with a small integrated LiPo battery with a capacity of 2 kWh.
This project is not driven by economic considerations. Overall, I expect to pay roughly the same amount each month for electricity as I do now without the photovoltaic system—at least.
Rather, it is motivated by my interest in experimentation and the fact that I genuinely enjoy working with exciting technical things. Also, I simply take pleasure in generating part of the electricity I consume (beyond the emissions created during production and installation) in a CO2-neutral (or more CO2-neutral) way.
With the small LiPo battery (I don’t have space for a larger capacity solution), the share of self-consumption rises from a little over 30% (without battery) to about 48%, based on calculations and projections. It never pays off financially due to the additional costs—in my opinion, however, maximizing self-consumption of the generated electricity is worthwhile. Just my personal quirk.
The east-west roof orientation is—not necessarily a disadvantage in my view—especially considering further increasing the self-consumption share. The system will deliver power in the morning, at noon, and in the evening, but overall it won’t be quite as efficient as a system with a purely south-facing orientation.
My questions:
1. Who among you already has a photovoltaic system with a buffer battery and can share your individual self-consumption rate?
2. What experiences have you had with east-west orientation for such systems?
3. What tools and methods do you use to further increase your self-consumption? I personally have somewhat “unusual” (?) ideas, such as simply waiting for a sunny day before running the washing machine, and similar approaches. Does this behavior bring any noticeable results?
4. Overall, how satisfied are you with your decision to install a photovoltaic system?
5. My house consumes less energy than what is currently predicted in the energy performance certificate. That is encouraging, but else nothing special.
However, if you add up the necessary electrical auxiliary energy (heating, circulation pumps, solar pump for the existing thermal solar system, controlled ventilation, etc.), a noticeable amount accumulates over the year. With the current primary energy factor for electricity of 2.4, and also with the upcoming year’s factor (primary energy factor for electricity = 1.8).
In combination with the solar system, recalculating the energy certificate would produce a better value since some auxiliary energy would be supplied by the photovoltaic system/battery. Also, the house would then generally generate a larger share of energy from renewable sources.
What do you think: Is it sensible and worthwhile to have the existing certificate recalculated after installation?
I would appreciate it if you could take the time to share your views and experiences with me. Thank you in advance.
Best regards,
Thorsten
At the beginning of 2016, I will be retrofitting my house with a photovoltaic system. It will have an east/west orientation with about 3.4 kWp per roof side.
The system will include an inverter with a small integrated LiPo battery with a capacity of 2 kWh.
This project is not driven by economic considerations. Overall, I expect to pay roughly the same amount each month for electricity as I do now without the photovoltaic system—at least.
Rather, it is motivated by my interest in experimentation and the fact that I genuinely enjoy working with exciting technical things. Also, I simply take pleasure in generating part of the electricity I consume (beyond the emissions created during production and installation) in a CO2-neutral (or more CO2-neutral) way.
With the small LiPo battery (I don’t have space for a larger capacity solution), the share of self-consumption rises from a little over 30% (without battery) to about 48%, based on calculations and projections. It never pays off financially due to the additional costs—in my opinion, however, maximizing self-consumption of the generated electricity is worthwhile. Just my personal quirk.
The east-west roof orientation is—not necessarily a disadvantage in my view—especially considering further increasing the self-consumption share. The system will deliver power in the morning, at noon, and in the evening, but overall it won’t be quite as efficient as a system with a purely south-facing orientation.
My questions:
1. Who among you already has a photovoltaic system with a buffer battery and can share your individual self-consumption rate?
2. What experiences have you had with east-west orientation for such systems?
3. What tools and methods do you use to further increase your self-consumption? I personally have somewhat “unusual” (?) ideas, such as simply waiting for a sunny day before running the washing machine, and similar approaches. Does this behavior bring any noticeable results?
4. Overall, how satisfied are you with your decision to install a photovoltaic system?
5. My house consumes less energy than what is currently predicted in the energy performance certificate. That is encouraging, but else nothing special.
However, if you add up the necessary electrical auxiliary energy (heating, circulation pumps, solar pump for the existing thermal solar system, controlled ventilation, etc.), a noticeable amount accumulates over the year. With the current primary energy factor for electricity of 2.4, and also with the upcoming year’s factor (primary energy factor for electricity = 1.8).
In combination with the solar system, recalculating the energy certificate would produce a better value since some auxiliary energy would be supplied by the photovoltaic system/battery. Also, the house would then generally generate a larger share of energy from renewable sources.
What do you think: Is it sensible and worthwhile to have the existing certificate recalculated after installation?
I would appreciate it if you could take the time to share your views and experiences with me. Thank you in advance.
Best regards,
Thorsten
Hi,
if they are LiFePO4 batteries, that’s definitely much better. The Dreamliner had and still has LiCoO2 batteries, which is a different league. They never really found out why those batteries caught fire, or at least never published the exact cause. In the reports available online, it said something about a "voltage drop," but no one knew why exactly.
The workaround is to fireproofly encase the batteries and simultaneously channel the combustion gases outside. Honestly, I find it somewhat ironic that packages with toys containing LiPo batteries are mostly no longer transported by airplane (too high a fire risk), yet they install huge batteries in planes.
If the inverter plus battery system is constantly connected to the internet, I would keep a very close eye on open ports, passwords, and so on. Unless they are significantly smarter than many other companies, there will be a standard login with a default password on it. If that isn’t changed, it’s only a matter of time before some script kiddies discover it and find it extremely amusing to disable the batteries remotely. With LiFePO4, the battery won’t explode in your face at least, but damaging it due to deep discharge is annoying enough.
Best regards,
Andreas
if they are LiFePO4 batteries, that’s definitely much better. The Dreamliner had and still has LiCoO2 batteries, which is a different league. They never really found out why those batteries caught fire, or at least never published the exact cause. In the reports available online, it said something about a "voltage drop," but no one knew why exactly.
The workaround is to fireproofly encase the batteries and simultaneously channel the combustion gases outside. Honestly, I find it somewhat ironic that packages with toys containing LiPo batteries are mostly no longer transported by airplane (too high a fire risk), yet they install huge batteries in planes.
If the inverter plus battery system is constantly connected to the internet, I would keep a very close eye on open ports, passwords, and so on. Unless they are significantly smarter than many other companies, there will be a standard login with a default password on it. If that isn’t changed, it’s only a matter of time before some script kiddies discover it and find it extremely amusing to disable the batteries remotely. With LiFePO4, the battery won’t explode in your face at least, but damaging it due to deep discharge is annoying enough.
Best regards,
Andreas
andimann schrieb:
If the inverter plus battery is constantly connected to the network, I would keep a very close eye on open ports, passwords, and so on. If they are not significantly smarter than many other companies, there is a standard login with a default password on it. If that isn’t changed, it’s really just a matter of time before some script kiddies notice and find it extremely amusing to disable people’s batteries. With LiFe batteries, at least they won’t explode, but damaging them through deep discharge is still quite annoying.Absolutely right. Your concerns show that you are very constructive and really knowledgeable.
I believe that is precisely what sets this forum apart from many others of this kind in a very positive way.
I have already mentioned the point you raised here.
According to the information I have so far, this is solvable.
Regarding port forwarding and similar issues, I will definitely dedicate some time to this topic before the system goes into monitoring (it has to, as this is part of the contract).
Once again, many thanks for your constructive input.
Best regards,
Thorsten
PS: ...hoping my questions in the opening post won’t be forgotten... I know there aren’t many systems of this kind yet... It would be great if photovoltaic system owners could share their experiences.
PS2: The Dreamliner matter is really fascinating. You are right about that, too.
PS3: Time’s up… haha.
Regarding monitoring: If the battery is about to enter a harmful discharge state, the entire system is shut down remotely via RC. This applies generally to all system parameters, which are monitored in real time; if limits are exceeded, the red switch is activated.
Of course, if a man-in-the-middle attack or similar blocks something here: everything breaks down. Script kiddies can be quite resourceful.
So once again: Great contribution from you, one (I) really needs to dedicate even more attention to the topic than before.
Regarding monitoring: If the battery is about to enter a harmful discharge state, the entire system is shut down remotely via RC. This applies generally to all system parameters, which are monitored in real time; if limits are exceeded, the red switch is activated.
Of course, if a man-in-the-middle attack or similar blocks something here: everything breaks down. Script kiddies can be quite resourceful.
So once again: Great contribution from you, one (I) really needs to dedicate even more attention to the topic than before.
T21150 schrieb:
My questions:
1. Which of you already have a photovoltaic system with a buffer battery and can share information about your individual self-consumption rate?
2. What experiences do you have with east-west orientation of such systems?
3. What tools and methods do you use to further increase your self-consumption? Personally, I have some “unusual” (?) ideas in mind, like maybe waiting for a sunny day before running the washing machine and similar. Does such behavior actually make a noticeable difference?
4. How satisfied are you overall with your decision to install a photovoltaic system?
5. My house requires less energy than the consumption figures predicted in the current energy certificate. That’s good but otherwise not very valuable.
Still, when you add up the necessary electrical auxiliary energies (heating, circulation pumps, solar pump of the existing thermal solar system, controlled ventilation, etc.), a noticeable yearly amount results. With the current primary energy factor for electricity of 2.4 anyway, but also with the coming year’s factor (primary energy factor for electricity = 1.8).
In combination with the solar system, wouldn’t a recalculation of the energy certificate show a better value since the auxiliary loads are partly supplied by the photovoltaic system and battery? Also, the house produces a larger share of energy from renewable sources in general due to the photovoltaic system.
What do you think: is it useful and worthwhile to recalculate the existing certificate after installation?
Hello Thorsten,
I’ll try to answer your questions as best as I can.
We have had a photovoltaic system with a 5.36 kWp south-southeast/east orientation running since 09/2014, without a battery. So naturally, my comments refer only to this setup. Additionally, we use our generated electricity solely for household power. The brine heat pump runs on a cheaper heat pump electricity tariff that is not allowed to be combined with photovoltaic.
Our annual self-consumption is about 20%. However, I must say we have generally been quite frugal with electricity. In our previous apartment, our household electricity consumption was around 2,700 kWh with two adults and two small children. The washing machine was used quite frequently. Appliances such as dryer, refrigerator, stove, cooktops, and dishwasher were replaced with modern units when we moved in. Only the washing machine and freezer (plus some small devices) remained older.
Of course, self-consumption differs between seasons. In July, our rate was about 19%, in February about 30%.
Regarding 3. Certain measures do help in my view:
- Running the washing machine and especially the dryer during high production periods is sensible.
- Programming the dishwasher to start, for example, at 12:00 makes sense if there is sun between 12:00 and 14:00.
- Other approaches - well, people who like to cook in advance and reheat in the evening save as well, although sometimes at the expense of taste and quality. Also, who is home during the day anyway?
Discipline is key here! Running the washing machine between 10:00 and 16:00, not in the evening or early morning. Also, anyone with small children knows: laundry must be done as it accumulates. Collecting it up for ideal timing is limited.
Someone supporting their heat pump with photovoltaics can increase self-consumption. However, don’t expect too much during the cold months. November is almost over and my system only produced around 160 kWh this month. About 60 kWh of that was self-used. January and February 2015 looked even darker.
A battery definitely helps to increase self-consumption. Whether it is cost-effective, I can hardly judge. Several providers (like Tesla) are entering the market and may shake it up significantly.
How much smart home technology from SMA actually helps is questionable—especially since smart home does not work with every programmable device.
4. We are satisfied with our photovoltaic system and would install it again—although the feed-in tariff has dropped even further since 08/2014.
5. Our general contractor (whose staff are qualified to issue the energy certificate) said that photovoltaics do not have a major impact on the rating in the energy certificate. Whether that is true, I don’t know. The impact could be bigger if the heat pump is supported by photovoltaics. Could be!
OK – I’m going to save energy now and shut down my laptop 😉. Good night.
😕. Nowadays, there are so many solar systems.
And so far, only one family has shared their experiences with me here.
🙄....Is everyone else just sitting in front of their inverters, completely frozen with enthusiasm over the readings???
Well....hopefully, I will have some data myself in a year. I’ll post it here then. Smile.
And so far, only one family has shared their experiences with me here.
🙄....Is everyone else just sitting in front of their inverters, completely frozen with enthusiasm over the readings???
Well....hopefully, I will have some data myself in a year. I’ll post it here then. Smile.
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