Thanks Mambo42. Very helpful to understand and clearly you have spent a lot of time determing what is right for your intended use. I wish I could find a good location on my boat for so much solar. That really makes a difference!
Originally my boat came with 4 x 150 wp solar panels which were attached to the railing of the upper deck. However there was a lot of shading, so the amount of solar energy was limited. That was the first reason for the upgrade to 400 wp panels.
I then saw on Youtube a guy who had mounted the panels outside of the boat. Everytime he would be moving he would fold the panels down and once at anchor he would fold them out again. So that became the idea of the first 4 panels.
Then came the question: 'where to go with the other 4 panels ?'
The logical place was the stern. We have predominantly Northerly winds in the Med during the summer, which means the stern is positioned to the South, ideal for solar and no shading.
After walking through the marina for quite a few days I had seen many solutions for attaching solar panels, but even better I found the welder who had made all those frames. The guy is a real genius and an outstanding welder, I have never seen such quality when it comes to welding.
So he came up with a frame that will be connected to the stern of the boat on which 4 panels will be attached. They will basically hang behind the boat as a sort of sun shade for the stern. At the same time this frame can be used to hang the dinghy under while under way. They dinghy will be about 1 foot out of the water, just below the passarelle.
Having the dinghy hang on the stern has three advantages for us. It clears up the dinghy deck, so that we can use it for chairs, sun beds etc. That deck area is 5 x 6 meters, so about 30 m2 or usable real estate.
Second the dinghy can be out of the water when we don't use it, so no growth of barnacles and no cleaning required.
Third, it makes entering the dinghy rather simple for us and the dogs.
Each solar panel weighs about 20 kg, so the total weight is about 80 kg. The frame itself is about 50 kg (I guess) so I am adding about 150 kg to the stern of the boat, which is not a problem.
To off set the weight in the stern I have added 40 mtr of 13 mm anchor chain for a total of 140 mtrs. That length enables us to anchor outside the charter boat anchorages at depths up to 20 mtrs with a 6 : 1 scope. The charter boats usually create one big mess in an anchorage, but they don't have enough chain with them to anchor safely in waters deeper than 10 mtrs.
The welder designed the frame in such a way (using 80 mm diameter SS pipes) that it can withstand about 65 kts of wind without a problem. He told me that many times that is where people make the mistake. They go for a smaller diameter pipe and find out that at 40 kts of wind the panels say goodbye to the boat. So I accepted his suggestion of the 80 mm diameter SS.
However, I saw a video on Youtube last week, which I am thinking of incorporating as well. This guy had 2 panels on the back of his sailing vessel, but had 2 panels below them, which he could slide outwards so that he has 4 panels while on anchor.
So am now in contact with the welder again and see if he can create something like that as well. Then I would have 6 panels on the stern, 4 on the sun deck for a total of 4 Kwp while on anchor.
When we are underway we will always have the 4 panels on the stern for 1.6 Kwp.
It may not look beautiful, but we are not in a fashion contest or most beautiful boat contest. The boat has to serve our needs and being able to get rid of necessity of the generator expands our sailing area drastically.
Also, the fuel prices will not go down anymore, only will go up and if we ever want to sell the boat the next owner will have a good reason to choose our boat.
I have to be honest and admit that I had a rough idea of what I wanted, but did not know how to realize it. So I literally spent months on youtube seeing videos about installing solar, solar on boats, positives, negatives, victron systems, lithium systems etc etc That gave me the opportunity to work out what I had in mind and after that I got in contact with the electricians and the welder to make it happen.
I would like to make everyone believe that I am crawling through the boat pulling cables etc, but am too old and too stiff for that. In my younger days I would have been able, now no more. I will be able to do my own maintenance, but installing it I leave up to the professionals.
