Invariably when a consumer is considering going solar they will have two or more companies pitching for their business with different solar panels.
Often the solar contractor with a higher efficiency panel will cite this as a good reason why you should purchase their system. It sounds reasonable that a solar panel with a higher efficiency should be more expensive than a system using less efficient solar panels but is it really worth paying more for panels with higher efficiency?
Efficiencies range from as low as 10% for cheaper thin film panels, to 14-15% for most polycrystalline panels and up as high as 20% for some panels that use more advanced technologies (or combinations of technologies). But does this mean that a consumer buying a 5kw system with a panel that is 18% efficient will get more kwh's of solar electricity than a person buying a solar power system with panels that are 14% efficient.
The answer is no! They will both get the same amount of power produced because the efficiency of the solar panel is already taken into account when rating a panel. This will mean that if two panels are both 300 Watt panels then they both produce 300 watts of power at standard test conditions (25C).
The only difference may be that the more efficient panel may have physically smaller dimensions because it needs less irradiation (and therefor less surface area), to produce its solar electricity, compared to a less efficient panel.
This is not to say that it is never worth paying a premium for a more efficient panel. The obvious case would be a situation where you have limited roof space and want to generate the maximum amount of power. There is an argument in this case to pay for a premium panel.
The second argument might be that often the the most efficient panels on the market are made by companies that are innovative, have excellent engineers and a high level of quality control. This may point to an overall quality and reliability advantage. This factor is sometimes called "bankability".
This site has the most reviews and ratings of solar panels and solar panel manufacturers on the web. By browsing the directory of reviews you can get a consumers perspective on each brand of solar panels. You can also ask questions on America's leading solar discussion forum at Solar Panel Talk.
On the reviews page for each solar panel brand you can see a list of solar installers in the USA that sell that brand so you can get multiple quotes on the same solar system in you wish.