When informing potential customer on the subject of commercial solar lighting, it is important to educate on the quality of the lighting system for long term use with a comparison to lower quality short term solar lighting solution. These systems cost much less than commercial grade solar lighting systems and will typically cause the customer more issues and more costs in the long run.
When choosing a solar lighting system, you should look for reliable solar lighting manufacturer with quality components and a warranty to back them up. You should ask for an actual light layout or fixture photometric of the light output of a particular wattage, mounting height, and distribution using an independent light program with at least IESNA standards in mind for the area to be illuminated.
The solar array and battery of a solar lighting system should be sized according to the wattage of the fixture, hours used per night (the longest night in winter if dusk to dawn) and average sun hours in winter when the least amount of sun is available for year round reliability. The size of the solar array should be enough to over replace the lost charge of the battery drained by the fixture every night. The battery capacity should be sized with back-up for inclement weather for at least 5 (more in some areas) nights of lighting in overcast conditions. This will also extend the life of the battery as you do not want a depth of discharge of more than 80% of the listed amp hours of the battery. In colder climates find out what type of batteries the company includes in their equipment and if they have problems freezing.
Keep these things in mind when looking for a sound reliable solar lighting system that will give you many years of lighting without the headaches or having to replace the entire system in a year or two. You usually get what you pay for, and in the world of solar lighting this is very true.