It was installed in May 2023 (Western Suburbs of Attica), it has a southwest orientation and there are no shadows. It has additionally been ordered with a second internal container (10 days waiting) to place a temperature instrument inside the container. Until November, one collector was covered due to high temperature...(I saw 96oC on the instrument). From November until today, both collectors are exposed to the sun. With an external (nighttime) temperature of 10-20oC, we have the following measurements. From night until morning, the temperature inside the container will drop by 8 degrees (max). When the water in the morning is at 30-40oC on a sunny (winter) day, it will be at 55-60oC at noon, which is perfect for everyone to take a bath. (200 liters) When it is cloudy or partially sunny, it heats up more slowly. The power usage is minimal. Of course, there are safety measures in place for overpressure, backflow, expansion tanks, overflow tank (cap) for thermal medium, and direct discharge faucets (the last one was needed). Note that the multilayer pipes used extensively in construction now have a maximum temperature resistance of 85-88oC, so the internal network must be protected from overheating. We will see its durability over time.

I cannot objectively comment on the quality as objective measurements would be needed. Visually, it appears to be of good quality.
The accessories, although they came from the company, all had some silly issues. One of the coolant bottles, which presumably come in barrels like that, was not properly sealed and was leaking in the box. The stainless steel pipes were significantly longer and I believe they need to be cut in order to fit properly. Also, they were cut incorrectly at some ends, and even though it is the plumber's job to cut them to size, I don't think they have the time to deal with it.
Regarding the base, I don't know if there is a reason, but it does not have wheels for all the bolts according to the design, and in some areas, the holes are so big that they barely touch the heads. However, overall, when you tighten the base, it is very stable. It required a lot of filling, I don't remember how many times I filled it. The water heats up, but we will see in the long run.

2 months of use. The water is boiling, not just warm. Usually, we turn the faucet a little to the left from the middle. You dare not turn it all the way to the left... you'll get burned.
Even on cloudy days, you have hot water. We took a bath with 5 people on the same day, after 3 days of clouds and cold weather, and the water was lukewarm on the 5th person. The next day, we had hot water again. Before this, I had a solar heater and it wasn't as good. Time will tell, but according to the plumber who recommended and installed it for me, if you do the services on time and take care of it, it can last up to 20 years.
The store where I bought it recommended covering one collector in the summer. I might do that, judging by how much hot water it produces.
I highly recommend it.

In the 4 years, the serpentine belt broke and even though it is supposed to be under warranty, the company avoids and does not recognize the validity of the warranty because I do not have receipts from the service, not only from the antifreeze that I knew was being used properly, but I should have also opened the flange from the side, they said, and that the warranty does not apply. I considered the company reliable, but it turned out to be much worse than my expectations. It definitely was not worth the money I paid. I feel deceived. I paid a lot of money that is not easily earned today, for a product that I believed had a warranty from a company that I considered reliable. Unfortunately, I was deceived. The product broke within the warranty period, and the company does not recognize anything because I do not have service receipts.

I declare very satisfied and I recommend it to interested parties. At first, I was a little hesitant! It's worth its money!

After a lot of searching, I also ended up with this solar panel for the following reasons:
1- Quality of construction (the collectors are monolithic like a boat)
2- The tank is made of aluminum on the outside, which helps in external conditions
3- The price is reasonable for what you get
4- It heats up with just a few hours of sun
5- Quick installation by a professional

Overall, choosing a solar panel is a bit of a hassle. My criteria were for it to heat up even on cloudy days, which this one does well since its collectors are made of copper.
Prefer a solar panel that has 2 collectors rather than one... the two perform better

After a long research, I ended up with this specific solar water heater and I haven't regretted it at all. I have had it for 3 weeks and it provides hot water for 4 people, even without strong sunlight. As soon as it gets a little sun, the water boils instantly. No matter how much I have tried to finish the water on sunny days, I have never managed to do it. I haven't even turned on the electricity yet, even on days with minimal sunlight, not even for 1 hour. Tremendous performance, very good build quality, highly recommended.

Update 3 years later and it still works perfectly. Frozen water for a week at minus 18 degrees and when it thawed, it had hot water for 4 people. If I had to choose again, I would definitely choose the same one with my eyes closed. It's worth every euro.