Comparing Solar

Having designed several small solar systems, I study existing ones with interest. Here's a fairly typical example I saw today. It costs R1 000. It lights up three globes, and by the looks of the full advertisement, it charges small devices, too. But when one does the sums on the specifications shown, the system, on a full charge, will be completely flat after little more than an hour, using only the bulbs (5W each). For me, I would want something robust, that really does the job: a full evening's light, including small devices. And that would not cost as much.