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nils-minor asked

Seeking Expert Advice on Optimal Solar Setup for Nulleinspeisung (zero feed)

Hello experts,

I'm in the process of planning a solar installation for my property and would greatly appreciate the insights of experts in the community. Here are the details:

  • Azimuth: 23° SE
  • Annual Consumption: 4000 kWh (approximately 10-12 kWh per day)

Description:

My goal is to install 4 PV modules on an exterior wall and a fence-mounted PV system adjacent to it. The challenge is to maintain a visually appealing setup without inclining the panels. Here are the specifics:

  • Fence-mounted PV: Flexible but without inclination
  • Wall-mounted PV: Horizontal due to space restrictions

I aim to achieve Nulleinspeisung (zero feed-in), meaning I do not want to feed excess energy back into the grid. Instead, I plan to incorporate a battery in the garage to store surplus energy. I have the capability to handle the installation myself, thanks to my relevant training.

I am particularly interested in hearing from experts on their preferred setups, considering the following:

  1. The size of the battery needed for optimal energy storage.
  2. Recommendations for achieving the right balance between cost-effectiveness and self-sufficiency.
  3. Insights on setups that prioritize both economic viability and autonomy, even if the payback period extends beyond three years.

Your collective expertise will be invaluable in guiding me toward the most suitable solution. Looking forward to your feedback and suggestions.

Thank you in advance!

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victron productsSolar Panelsetup
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5 Answers
regman54 avatar image
regman54 answered ·

I'm no 'expert', just sharing my experience.

What stands out to me is the decision to place the panels vertical. Doing so you won't be using the panels to anywhere near their full potential. Yes it will look better but very inefficient. The panels will only work at their best while pointed directly at the sun so something you'll need to compensate for when calculating the needs of your project.

At what latitude you do live? That too will have an impact on how much energy the panels can absorb.

I'll let the experts weigh in from here.

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nils-minor avatar image
nils-minor answered ·

Hey, thanks for your feedback :) Do you have any numbers how much the efficiency will go down if I mount them horizontal instead of vertical? I know it would be better to have some angle but this will not look great on the house wall :/

I live in central Germany (latitude 50.142979). The south side off the house really has a lot of sun per day.


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jochenku avatar image
jochenku answered ·

HI Nils,

there are several free PV simulation tools on the web. I normally use PVGIS and the results are very close to what I see in the real operation of my PV.

Simply enter your planned PV arrays one by one, select different slopes and note the variing results per month and per year. The results can be exported (eg. as CSV) and thus further processed.

Best regards, Jochen

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ejrossouw avatar image
ejrossouw answered ·

@Nils Minor Below is some interesting insight you and other respondents may find surprising ;) The was also a recent Dutch study, if I remember correctly, that indicated under certain conditions because of better airflow and being cooler, vertical panels perform better, not derating as other roof mounted installations would. I also have customers with fence mounted installs and will find data when time permits. My own tests with a tracker surprised me even more when there was no visible sun to the tracker it pointed to an opposite wall from where the irradiance was deflected. In summary my advice is, don't discount vertically mounted solar, as there will be times when it may perform better. Currently vertically mounted solutions are gaining traction in light of new studies.

https://www.pveurope.eu/solar-modules/germany-high-self-sufficiency-photovoltaic-system-north-facing-roof

https://www.pv-magazine.com/2024/01/16/solar-fences-stand-out-in-australian-market-simulation/

https://www.pv-magazine.com/2023/11/10/researchers-shed-light-on-mysterious-higher-energy-yields-in-vertical-pv-systems/

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nils-minor avatar image
nils-minor answered ·

Thanks a lot for the helpful content :)

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