Gather small solar cells, tabbing wire, bus wire, flux pen, soldering iron, solder, diode, backing board, glass or clear acrylic, sealant, and junction box
Plan the panel size and number of cells needed for the desired voltage and current
Arrange the solar cells in series or series-parallel on a flat surface
Clean the cell contact points carefully
Solder tabbing wire to the front contacts of each cell
Connect the cells together by soldering the tabbing wire to the back contacts of the next cell
Test the connected cells with a multimeter for voltage output
Fix the connected cells onto the backing board with adhesive or mounting strips
Connect the panel output wires to a blocking diode and junction box
Cover the cells with glass or clear acrylic
Seal the edges with weatherproof sealant
Let the sealant cure fully
Test the finished panel in sunlight with a multimeter or charge controller
Mount the panel in a sunny location with the correct tilt angle