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
f-pNo schrieb:
Self-consumption 2015 (ratio of total household electricity consumption to self-consumption): 70.16%
(Calculation: (electricity supplied + self-consumption) vs. self-consumption) Correction. It’s definitely better to post when fully awake.
I had the feeling all along that something was off with the calculation.
The method is correct—you just have to follow it through:
The correct ratio is: 40.23%
In my opinion, still very good.
N
nordanney8 Jan 2016 09:47Well done, for us it was "only" 35% in 2015.
Hello everyone,
I have a question whether I’m on the right track or if this is financially worthwhile. I would appreciate your opinions.
The house is KfW55 standard – construction started May 2016.
260m² (2800 sq ft) heated floor area – approx. 10kW ground-source heat pump.
South-facing with a 45-degree roof - 6kWp (kilowatt peak) building-integrated photovoltaic system from Solarworld including installation and Kostal Piko 5.5F inverter (€8670 net).
Installed by my carpenter. Integrated into the roof for aesthetic reasons.
Bavaria currently has the “10,000 Rooftops” program running.
This means for “grid-friendly photovoltaic” = photovoltaic system + battery + heating element and maximum 30% grid feed-in, there is an €8000 subsidy + the KfW subsidy 275 of about €3000.
This would cover the Solarworld Sunpac Lion storage system with 6kWh usable energy (€9966 net).
Is my calculation correct? Is the maximum 30% grid feed-in limit absolute nonsense or achievable?
Self-consumption is supposed to be the key going forward with a feed-in tariff of 12 cents per kWh, right?
I think I may have underestimated the problem of low photovoltaic yield in winter and high photovoltaic yield in summer...
Are special devices needed to use the photovoltaic electricity for the heat pump?
Alternatively, the “grid-friendly photovoltaic” option with photovoltaic + battery and max. 50% grid feed-in subsidy of €6000 can be applied for.
So far, only the KfW application 275 has been submitted – before 31-12-15.
Many thanks and greetings from Bavaria,
Flo
I have a question whether I’m on the right track or if this is financially worthwhile. I would appreciate your opinions.
The house is KfW55 standard – construction started May 2016.
260m² (2800 sq ft) heated floor area – approx. 10kW ground-source heat pump.
South-facing with a 45-degree roof - 6kWp (kilowatt peak) building-integrated photovoltaic system from Solarworld including installation and Kostal Piko 5.5F inverter (€8670 net).
Installed by my carpenter. Integrated into the roof for aesthetic reasons.
Bavaria currently has the “10,000 Rooftops” program running.
This means for “grid-friendly photovoltaic” = photovoltaic system + battery + heating element and maximum 30% grid feed-in, there is an €8000 subsidy + the KfW subsidy 275 of about €3000.
This would cover the Solarworld Sunpac Lion storage system with 6kWh usable energy (€9966 net).
Is my calculation correct? Is the maximum 30% grid feed-in limit absolute nonsense or achievable?
Self-consumption is supposed to be the key going forward with a feed-in tariff of 12 cents per kWh, right?
I think I may have underestimated the problem of low photovoltaic yield in winter and high photovoltaic yield in summer...
Are special devices needed to use the photovoltaic electricity for the heat pump?
Alternatively, the “grid-friendly photovoltaic” option with photovoltaic + battery and max. 50% grid feed-in subsidy of €6000 can be applied for.
So far, only the KfW application 275 has been submitted – before 31-12-15.
Many thanks and greetings from Bavaria,
Flo
N
nordanney8 Jan 2016 12:17Flose89 schrieb:
I think I have overlooked the issue of low photovoltaic output in winter and high output in summer... That is the major problem when you produce 30 kWh or more on nice summer days, have no significant consumers, and the battery is always full...
We have a 7.x kW peak system, work from home, three children with high washing machine and shower usage, and yet we didn’t manage to consume more than 35% of the generated power ourselves. We have 300 m² (3,229 sq ft) to heat, and the heat pump’s electricity consumption in 2015 was only 3,011 kWh for heating and hot water (of which nearly 60% was used in January, February, November, and December) – so there was hardly any consumption in summer and a significant overproduction.
Thank you for your reply/experience.
The question is: Is the generous subsidy or the feed-in tariff over 20 years more worthwhile...
Assuming I "lose" or do not feed in 3000 kWh per year. The rest is self-consumption plus the 30%.
3000 kWh × €0.12 × 20 years = €7200... compared to an €8000 subsidy — that's about a break-even, right?
The question is: Is the generous subsidy or the feed-in tariff over 20 years more worthwhile...
Assuming I "lose" or do not feed in 3000 kWh per year. The rest is self-consumption plus the 30%.
3000 kWh × €0.12 × 20 years = €7200... compared to an €8000 subsidy — that's about a break-even, right?
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