Most Solar powered bike computers that are out there are horribly cheaply made and come direct out of China. However I did find one company that makes a decent solar powered bike computer, here is the link: Solar Flare Cycling Computer

Keep in mind that all solar powered devices have a battery, the battery is kept charged by the sun, and like all rechargeable batteries they too will die though it may take about 5 to 10 years.

Wired computers are more reliable than wireless, and with a wired computer you only have the computer that uses a battery which can usually last at least 2 years, whereas a wireless unit has a battery in the sending unit and those die after about 6 to 12 months depending on use. Wireless units weak point is the sending unit, so far I haven't found one that lasted more than 3 years, my current VDO wireless computer is now 3 seasons old and still working so I'll see if it lasts longer than my previous two Cateye wireless units (actually 3 because Cateye replaced the first one under warranty). In comparison my previous wired job lasted 25 years, and I have two wired Sigma units that are 5 years old and still going strong.