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Array Encapsulation Testing

Michigan State is one of a few schools that encapsulate their solar array by hand. Manually encapsulating, although more work than buying panels, gives us not only more flexibility in our design and ability to fix issues with the array but gives team members a greater understanding of how solar technology works and the challenges with creating a good product.

You can see in a past blog post the encapsulation process we used for our last array which used a continuous baking process to protect the cells between layers of EVA (Ethylene-vinyl acetate). This year we are looking to bake our cells statically in a standard oven with more layers, a back sheet and a top glass layer, for greater stability and protection.

Before we go and try baking sheets of cells in an oven we are doing single cell test runs in a small toaster oven to see what will work to get the best finished product.

Here you can see we’re preparing a single cell to be baked. The blue tape around the edges is to seal the materials in order to create a vacuum while the in the oven.

 

The toaster oven and vacuum pump set up.

 

One of the biggest difficulties is baking the cell under the right pressure and temperature conditions to have no air bubbles trapped in the EVA after it has cured. You can see in the final result of the first test run below that air bubbles were a problem.

Final Result
For the next test we used fresher EVA, monitored the temperature inside the oven more accurately and baked the materials in between two 7″x 7″x 1″ Aluminum plates for more consistent applied pressed.
Letting the Aluminum plates heat up before inserting the materials.

 

The packaged materials
The final results!
Looking at the results from both the tests side by side, as seen below, there was a major improvement in bubble reduction although still not perfect. By continuing to further tweak the bake and cure temperatures, times and pressures we should get it down soon!

 

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