Hi Viktor, sorry for the mis-spelling on your name.
You asked for an opinion, and i didn't quite do that in my first post.
I have spoken to several people on websites that sell professional systems, and they all say that you cannot even begin to compete with a professional system.
I do tend to agree.
Why ?
Because they make use of the sq.footage of an area, 100%, a 4x10 sheet = just that, 40 sq.feet
I have a 4'x8' sheet of plywood - in theory that's 32 sq. feet, but....
much of my 4x8 sheet is not usable, the corners, and also the middle where I was not able to bend the pipe, and had to stop my coil there, - so in reality,
that 4x8 sheet of plywood with blackpipe has a LOT of wasted space.
Look at the image below.
Also, let's remember that most black pipe homemade systems are 1/2" pipe....
the professional ones are 1-1/2" pipe ! .... the gallons per hour these things push out is unbelievable, so there's just no comparison. I like tinkering, and don't have tons of money so I made 3 homemade systems, but scraped up money to buy one professional panel to test, and keep. I have put in all the tubing this week, in anticipation of my professional solar panel's arrival. I have it running from my pool's pump, under the deck and into a part of the backyard where I'll put the solar panel on the ground and test it.