Power from the Sun…

The solar panels are coming along. A bit slower than we would have liked since we have had some finish work and some gotcha’s getting the kitchen completely ready to go, but we’ll leave that for another post. In our last post, the solar cells were being soldered together.

Solar PV systems have a fluctuating power output based on how much sun is available, so they rely on a device called a charge controller to regulate the power that is produced. In most cases this is used to charge a battery (this is how we are going to use it). The charge controller is generally rated for a set amount of both voltage and current. In our case we have a charge controller that has a max amperage of 10 Amps and a max voltage of 100V. Our solar panel is two parallel smaller panels of 36 series cells each. A little math gets us to the fact that the panel will output 20V at 7.2 Amps in a best case scenario.  That is around a 140 watts of solar power.

So we have the strings of cells soldered together and the next step was to attach the cells to the panel. We used clear silicone adhesive to glue down each of the sets of cells

Fun with silicone… putting the strings of cells in place was a bit nerve wracking since they are so brittle.

The panel sections all connected down. There is still some interconnect wiring to be soldered in that is not shown in this picture.

The panel is a layered affair starting with an aluminum frame that I custom built from a scavenged frame of a broken hot water solar collector. I cut them down on a band saw to make L angle pieces and then cut and bent them to get the frame shown here.

Bottom side of the scavenged frame.

The frame in all its recycled/scavenged materials glory

Next we are putting down a piece of thin aluminum sheet metal (also scavenged) to provide some weather protection for the panel backing.

Sheet aluminum on top of frame.

The cells are attached to heavily primed and painted 1/4 inch plywood which goes on top of the sheet metal

The framing sections that hold the panel pieces in place.

Then panel sections are housed in a channeled frame that I made from ripped down 2x2 and 2x4 lumber. This was also heavily primed and painted.

This is the how the final panel will look with the addition of a sheet of Plexiglas on top.

There will be a sheet of 1/4 inch Plexiglas on top of this to protect the cells and the whole thing will be through bolted together with stainless steel bolts. Hopefully, we will get the panel fully assembled by the end of Saturday and the weather will give us some sunshine to mount this on the roof of the trailer and get all the internal wiring done.  Someone asked (sarcastically I might add :) about the weight of the panel. I think the whole thing is going to come out weighing around 30 lbs which is pretty good for that amount of power. I tried this out at twilight (literally… the sun went behind the mountains while I was setting the panels up) and was still getting 16.85 Volts and 1.36 Amps with no direct sunlight, so I’m pretty happy about that. We’ll see how this actually works once we get it all assembled.

--Tom