To build your own solar panel, you'll need to assemble the pieces, connect the cells, build a panel box, wire the panels, seal the box, and then finally mount your completed solar panel. Solar Combiner Box diy projects let people control many solar strings in one safe box. They help save money and give a chance to learn by doing. Anyone with basic electrical skills can try this. Built instructions and datasheets. Before you specify hardware or cut conduit for a solar combiner box, confirm the following design inputs. There are a few different types of solar cells to buy, and most good options are either made. These are step by step instructions on building your box and putting your solar cells together.