If you can identify which is the voltmeter and which is the ammeter, it should be simple. Say the solar panel has output wires of Red (positive output) and black (negative output). The ammeter goes in series with the load (cut the red wire and insert there). Voltmeter goes between Red (solar panel side usually) and Black. That accounts for four wires. The fifth wire may be an earth ground but I'd be guessing. If you can post a link from the manufacturer, I will comment further.