So as previously mentioned, the power solution is a solar panel, charge controller and storage battery.

Source

For the solar system I scoured Ebay for sellers of complete systems, working on the premise that they are more likely to work together, I came up with this device (if the link stops working search for 100W, 12v solar system).

I would recommend this seller specifically due to my experience, unfortunately the panel arrived with the front glass shattered. I took a picture and asked the seller what could be done about it, he immediately shipped a new one at his expense, and told me to keep the broken one. There are plenty of results on google when you search "repair shattered solar panel" and on testing them, they are both producing about the same power.

I did not find any mounts local to my home, so I made some brackets myself. I had some xmm thick aluminium plate (yes, that's how I spell it) and cut 4 strips, 25mm wide and 90mm long. I made marks 25mm in from each end, and drilled holes centered in the squares. Once they were cleaned up on the linisher, I put 90° bends on the 25mm marks.

These brackets were then bolted to the frame of the panel so the panel stands about 35mm off the surface, on feet that have a hole in the middle. The feet are then screwed into the decking of the roof using 1.5 inch stainless screws. I did not worry about painting them, as the combination of aluminium brackets and stainless steel hardware will not rust. Before driving the screws into the decking, I lifted the foot, and pumped a "good dollop" (yes that's the technical term) of caulk under the foot, and wound the screw through it. With the idea being that the caulk will set and help seal the hole from the screw, keeping the roof watertight. If this was my house roof I would probably put a little more effort into keeping the water out, but the dock is outdoors and in the weather anyway, so if it does leak, it's not the end of the world.

Distribution

From the panel, the electricity is directly connected to the charge controller, which is under the dock. As this is a high current path, I have used 12 gauge low voltage cable. It is stapled neatly under the eave and into the "trench". The charge controller is also connected to the battery and the rest of the system is connected to the load terminals. The battery is protected by a 15A inline fuse, the controller has 15A maximum output so I would be very surprised if this blew. The rest of the wiring is also fused near the controller, this time at 10A. This will protect the charge controller and wiring from a short, and should keep the dock from catching fire. I will measure the final system at full brightness to see what the expected worst case current draw is, and resize the fuse to match. After the fuse, the load cable runs down the trench to the gazebo connector, and then under the eave, down the back of the roof support and under the dock. Again this is a high current path and is cabled with 12 gauge wire.

Once under the dock, the wire is stapled to the sides of the support beams, and makes its way to the middle of the dock. At this point the wire has connections to the cable that leads to the postcaps at the end of the walkway as well as the postcap in the middle at the back where it splits again to reach the other postcaps. All under dock wiring is considered high current and I used 12 gauge. At each post location, the power for the postcap is tapped off, this time on 16 gauge wire as it only supplying a single light controller. The light controller cable then makes it's way above the decking using a convenient gap and is then hidden under the "pretty board" to the entrance hole, and up the longitudinal hole. See the postcap install section for more details.