Hey Bob, I'm chuckling at your confusion because it's a confusing subject. Here is a little online calculator that may help:
http://www.ohmslawcalculator.com/ohms-law-calculator For solar panels, there really is no rating convention. For example, 100-watt panels are popular. Manufacturers can easily "rate" a panel as 100W by adjusting the voltage it's rated at. If all panels were rated correctly (in my mind that would be 14.1V) then you could easily tell the output. So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.
I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.