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Balkonsolar - one year in review- 2 January 2024 - (0) Comments

Thomas Hampel
 2 January 2024

It was exactly one year ago that I've installed a tiny solar power plant at home, referred as "Balkonsolar" here in Germany.
Now after exactly 365 days of being "empowered" - its time for a review.

Image:Balkonsolar - one year in review

Where it all started

I've been fascinated by solar power and heard about micro installations on balconies a year or two before, watched some YT videos to understand the benefits and constraints.
Previously I thought only large scale installations can provide a return on invest, but it turned out that even two panels or even just one are enough for a valid business case.
I was blown by the idea that money is litterally falling off the sky and one just needs to collect it.

Sure I could have used
Photovoltaic Geographical Information System (PVGIS) to estimate the power production at my location, but why bother about details.

Stage #1 - Get the equipment

I've spent way too long with the decision to buy the equipment. All in all it took over a year from the idea (early 2020) to placing an order (early 2022).
Back then one could buy a whole set for >800 EUR or just order components one by one for a total of € 600 or less. My preference was for buying components separately and plug it all together myself.

Stage #2 - Waiting

(Un)fortunately my order was placed right before Russia started invading Ukraine, which caused the energy prices to skyrocked. So solar panels and power converters prices increased by a factor of 3 to 4.
I was in doubt if my order will actually be shipping since the seller could make 3x the money by cancelling my order and selling to someone else.
To my surprise, just 5 months later I got what I payed for.

Stage #2b - Waiting (for myself) & Being busy with work

My job does not allow for lots of hobbies or side projects, so despite high energy prices I had no time for installing the panels.
All equipment remained unused for 9 months(!).

Stage #3 - Chaising approvals

The ugly part of wanting to install solar panels at your balcony is that you need to seek approvals from your landlord who must allow the installation, home owners have an advantage here.
Luckily the legislation is expecting to change next year so that it is preapproved. Also various other regulations exist that may drive you nuts.
e.g. standard power plug or solar-plug?,
Also there are legal limits of (just) 600Watts, while neighbour countries like Austria allow 800Watts of power production. Not logical why, just damn German bureaucracy & big lobby groups trying to protect their own business
However, not everyone is against my project so after sending a mail or two, I got the approval from the landlord to proceed at my own cost.

Stage #4 - Installation

It took until Christmas 2022 until I've had time to do the installation.
It turned out to be far easier than expected. All-in-all it took about 6 hours, where most of the time was spent with cable management on my balcony to make it look nice.
Since the inverter came with mandatory cloud connectivity + mandatory data processing in China, I never connected the WiFi interface to my home network for security reasons and instead was looking for other options to measure solar power production.

Tip : Assembly/installation is far easier with the help of a friend... and besides that is more fun too.

Stage #5 - Paperwork

It's Germany, so of course you have to fill out boring paperwork to register this installation.
As a polite citizen I did that promptly. All in all its a 15min process in two places:

your local energy provider and a country wide register (

Stage #6 - Metering

Certainly I wanted to know how much energy is produced.
Most micro-inverters already come with WiFi antenna and a smartphone app, harvesting all your data in a (more or less) "secure" cloud.
Personally I do not recommend to allow those kind of devices to access my home WiFi nor the internet.
For good reasons as it turned out, because e.g. Deye / Revolt / Bosswerk inverters allowed anyone to read your WiFi password in clear text, a big security hole - for details see
this thread

So I went the lame route for metering: I'm using a well established
AVM Fritz!DECT 210 device.
Based on your personal preference and type of inverter you might also be interested in
this kit from

What's the total cost?

Total cost (when I bought it in 2022) was EUR 600,- meanwhile prices have dropped and
legislation has changed so that there is NO sales tax on solar equipment anymore.
0% sales tax means from one day to another you'll save 19% !
All together the same or slightly better equipment that I bought back then is available now for a much lower price:

EUR 180,- for 2x Panels (€ 90,- each)
EUR 140,- for 1x Hoymiles HM-600 (or 800)
EUR 80,- for panel mount/equipment
EUR 50,- for some 5m solar power cables,adapters and other small parts
= EUR 450,-

+ optional EUR 55,- for a
AVM Fritz!DECT 210 which connects to my AVM Fritz!Box (Router/SmartHome Hub) for measurement & statistics.

The Result

After exactly one year, these are the plain figures:

Produced : 429,4 kWh

It could have been more (639.63 kWh) if my panels would be mounted in an ideal position and not just hanging at 90degrees

I've returned 63 kWh to the grid (for free) due to producing more than what I have used. This was mainly driven by being on vacation.

At a current price of € 0,4905 / kWh it results in savings of
€ 210,62 for 2023
Indeed this rather high cost per kWh is in our contract - it was the cheapest option in 2022 when energy prices skyrocketed.

However, due to
other regulations in our country some might say that I should only calculate with € 0,40 (the capped cost) which would result in approx. € 171,76 of net savings
I am including the energy I have returned to the grid worth € 25 in my savings calculation because it was on me to use it.

Here is the chart showing power production over the course of the year

As you can see the month of May was the best month so far as it provides a good amount of sunlight at mild temperatures.

Image:Balkonsolar - one year in review

For this year (2024) we are expecting a cost of € 0,32 /kWh which would generate approx. € 272 of savings per year
Assuming an 800W installation at an ideal angle.


Is it worth it ?

Absolutely YES YES YES !
At current energy prices and prices of new solar panels you'll have a return of invest in under two years.
That is comparable to an interest rate of >50% - where on earth do you get that for your bank account?

My advise:

Dont wait, START NOW and install as many solar panels as you (leagally) can.
Two of my friends were amazed by how easy it is to enter the solar power business, so I helped them buiding their own "Balkonkraftwerk"

Cool projects I came along



Photovoltaic Geographical Information System (PVGIS)
Solardach Potential Germany
- Heise Ratgeber Balkonkraftwerke
BMWK: Senkung der MwSt. für private PV Anlagen auf 0%
- Blinkyparts -
OpenDTU Bausatz


Closing with a key message from 34c3:

Image:Balkonsolar - one year in review
Thomas Hampel, All rights reserved.