When using the SunControl board, you need to look at the VOC (Voltage Open Circuit) of any other solar panel you have. If it is above 6V, you need to add in a 10W 5.6V Zener diode across the solar panels to protect your SunControl board and system. Connect the "+" end of the diode to the "+" side of the solar panel (or the line from the solar panel to the SunControl Board) and the "-" side to the negative ("-") side of the panel. This will get hot, so let it hang free in the air.
Unfortunately, you can’t just put 10 1W 5.6V Zener diodes in parallel. They aren’t identical and the one that is slightly lower will take all the current. You can, however, stack them in series to acquire the appropriate voltage and power dissipation. Such as stacking 2 5W 2.8V Zener diodes.