In video #426, I started my do it yourself journey into solar energy with three neighbors
and the help of a cooperative.
The analysis showed that this method should save us about 40% and also should be fun.
Is this true?
Were our commitment and knowledge good enough?
And where do we stand today?
Grüezi YouTubers.
Here is the guy with the Swiss accent.
With a new episode and fresh ideas around sensors and microcontrollers.
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We want to build four independent solar plants on our flat roof.
They should be built as one project to optimize the panel area and the cost.
We got help from the “Energiewende” cooperative, which supports homeowners with planning, construction
site management, and material purchased in bulk.
We decided on an east-west configuration of the panels because it leads to more energy
produced per roof's surface.
And we wanted to mount the panels on an aluminum grid without any attachment to the house.
This led to many viewer questions about high winds.
Fortunately, we do not have hurricanes where I live.
And the supplier of the mounting system provides a ballast plan.
Their calculator is online if you want to try your location.
We will later see how the ballast is applied.
With this information, you can decide if it would be good for you, too.
The next question came instantly: Will the roof support this big load?
Our roof is made from concrete and, as you might know, the Swiss are prudent.
So we build everything as it should be and then add a safety factor of at least 3-5.
Panels, mounting system, ballast, and mats weigh not more than 4 tons, and the area is
240 square meters.
So the load is 17 kg/square meter.
Compacted snow weights up to 200kg per cubic meter.
So our load is about 10cm of snow—nothing to write home about here in Switzerland.
The third question came about the rain.
Here we have to hope that we did not harm the construction and it will stay waterproof.
Also here, you will see why we are hopeful that this is the case.
Another question came a few times: Why did you mount the panels fixed and not turn it
with the sun?
Our panels are 2x1m.
You can imagine what mechanical effort it would need to turn them.
Such a construction would be much more than the 150 dollars for one panel.
Not to forget the maintenance.
So we can start with the build.
One week before the official start, the first thing arrived: An elevator to move the heavy
stuff up and down.
Next came the scaffolders and mounted protection around the roof.
These people do not know the word “fear,” and they work extremely hard.
I got tired by just watching them.
Now we were able to start the project.
But wait: We have a “green” roof with soil and plants.
What was made to protect the membrane now leads to a very uneven surface.
So we had to remove all plants and level the soil.
This was very hard and took us a few days.
Here it was precious that my neighbor Hugo helped out.
He worked extremely hard to get this job done.
Because we did this work one week before the official project started, my second and third
neighbors were still at work.
Because the solar panels will change the climate on the roof considerably, new plants would
start to grow.
And also, the big ones would love the shadow of the panels and fight with us for solar
energy.
This is why we had to add so-called “Regupol” mats.
They are pretty heavy, absorb all light, and should not rot.
Each roll weighs nearly 100kg, and we were happy to have the elevator.
The weather was not always good, but we kept on working.
Getting the surface leveled took us much more time than anticipated.
But finally, we had all mats deployed.
These mats had to be glued together, and we had to leave out the spaces for our exhaust
pipes.
Not an easy task because you do not get a second chance if you cut it wrongly.
But we got it right for all four houses.
As an electronics engineer, I completely ignored this part of the work.
I was not prepared to do gardening.
I wanted to do electrical stuff.
Unfortunately, after this week, we were already tired.
And the “real” work was still ahead of us.
The panels, the inverters, the batteries, and much other stuff were delivered by Friday.
So we were ready to start on Monday with the layout of the mounting system.
Because we planned as many panels as possible on the roof, this was not easy.
Because the exhausts are higher than the panels, we had to leave out one panel per house.
We also had to separate the rails in the middle because of the temperature expansion of the
rails.
To circumvent the exhausts was a big challenge.
And here we learned a lesson I should have known for many years: The story about Herby
from the highly recommended book “the goal.”
In this story, we learned that we have to put the bottleneck resource at the front of
everything and offload it as much as possible.
Only then do we get maximum performance of the system.
So what was our bottleneck?
It was Sebastian, our project manager.
In the beginning, he had to do most of the work.
And the rest of us was eager to work but did not have the know-how.
Lazy people would have made a break and let Sebastian do his job as fast as possible.
Not we.
We asked him questions and tried to do some work, just to show how diligent we were.
Later we learned that most of this work was wrong and had to be un- and redone.
So the first learning: Taking a break sometimes is better than showing off how motivated you
are.
After the layout was somehow fixed, we started to connect the rails and mount all the holders
for the panels.
Here you see me working.
Just that you do not think I was lazy.
With Sandra and Jonas, the other neighbors, and my brother, we now had more help.
If you think we did not have to move these mounts several times, you are wrong.
The efficiency of our team was as expected: It was on a beginner’s level.
But, we were motivated and worked hard.
And as planned, we had lunch together—each day at a different house.
So we learned to know each other a bit better.
This picture shows the situation before we started to mount the panels.
It looks pretty neat.
But the devil is in the details.
The sun was now shining, and we had already nightmares about all the lost energy.
So we wanted to hurry up, which led to more rework.
We wanted to see panels on the roof and had enough workforce to move them up.
So Sebastian could no longer withstand the pressure: We were allowed to bring a few panels
up.
So we were happy!
The project had visible effects.
We did not know that probably the most crucial task after positioning the panels is to layout
the cables.
As said before, every home had the same setup: A west string with seven panels and an east
string with eight panels.
Hugo and I have two more panels in the west string because my house at the end has a bigger
roof.
The panels in one string are connected in series.
So the total open circuit voltage is 9x50.1V=450.9V. No problem for our inverters.
I thought the cabling was like batteries: Connect a wire to the minus and a wire to
the plus end.
But I had to learn that this is not done like that.
The minus cable has to run in parallel below all panels.
Please do not ask me why.
But with this plan, the minus cable has to be much longer than the plus cable . And all
cables have to run in aluminum pipes when they cross open space to protect them against
the sun.
Because we did not want to have unnecessary cuts in these cables, we already now had to
think about the overall cabling and the position of the inverters and the batteries.
The easiest way would have been to put the cables along the exhaust pipes.
But unfortunately, the builders did thorough work and closed all spaces with concrete.
So we had to take a detour.
As you can see, this is not easy because all of us decided on a different way for the cables.
My cabling was straightforward because my house is at the end: One aluminum pipe down
to the basement where the inverter will be mounted.
So my cables were from 20 to 42 meters.
My neighbors had to go a much longer track: First across the roof, then down to the basement,
and then inside the basement, back to the front.
Their cable length was up to 60 meters.
The mounting rails and the pipes have to be connected to the earth, btw.
As you see, Sebastian had a numbering scheme for all wires.
And I can reveal a secret: The cables were long enough.
But only after significant rework.
Speaking about cabling: The standard connector in the solar world is the MC4.
I have to mention that because it was invented by Multi-Contact, a Swiss company.
Fortunately, most suppliers use them now, and it is easy to mix and match things.
So the next step was to cut the cables and lay them out.
Unfortunately, the others did not have work, and I am sure you guess what happened: No,
they did not drink a beer or two; they moved additional panels to the roof.
Here is the resulting situation: The cables were not laid out, but more panels were lying
around.
You also see another essential ingredient: The ballast stones.
They came from Jonas.
He wanted to change the layout of his garden.
So his stones have a second life on the roof.
After the layout of the cables, we started to mount the pipes.
Sebastian is a mountaineer in his free time, and he went up the long ladder to drill the
holes.
This is how it should be done, BTW—secured against a downfall.
By Lucas, the son of my wife.
We also had to drill big holes into concrete.
Fortunately, we had the right tools as well as the right man!
He started from the inside with a small pilot hole and then from the outside the big one.
In the meantime, we got new neighbors: A circus.
I did not expect that it would show up after Corona.
Already before, it was a tough business with fewer and fewer spectators.
After mounting all pipes, we were ready to move all panels up, mount, and connect them.
Here Marvin, my former assistant, was a big help to Sebastian.
We had to add the ballast before mounting the panels because they are close to the floor.
As said before, we got the ballast calculations from the manufacturer.
You see that most of the stones have to be placed where the wind could enter.
Because this is close to the walls, it reduces the load on the roof.
A simple system ensures that they do not move after deployment.
This work was fun.
Now we got what we had to wait for the whole week: Panels on the roof.
Here they mount the last one, and here you see the result of two weeks' work: The first
week's work is entirely covered by the second week's work.
Mounting the panels alone took one week.
So four solar plants in 6 days are 1.5 days for one.
Not bad.
We were proud, and because it was Saturday evening, we celebrated a bit.
You see, Jonas is German.
In the next episode, after the summer break, you will see if all connections were ok and
how we will finish the details on the roof, including the mounting of an optimizer in
the shadow of an exhaust.
We will also cover the installations in the basement consisting of the inverters, the
batteries, and the smart meter.
And maybe I can already tell you how much my panels produced.
One last thing: My brother and his neighbor had a similar
project in parallel and without telling me.
Here, a company did the installation.
So we should be able to compare the cost per kW peak.
And our neighbor across the street started to remove his roof because he will get integrated
solar panels to replace his tiles.
He has to wait for a little longer till the material arrives.
So we have another concept to compare.
This was all for today.
As always, you find all the relevant links in the description.
I hope this video was useful or at least interesting for you.
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Thank you!
Bye