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To the surprise of most people, there is almost no limits to the size of solar lights! The modern industrial solar lights can be used (and are used!) to light up tennis courts.
As to how long they can last, a good modern commercial strength solar light can last up to 3 days after a full charge.

Solar lights come in various styles, sizes, and shapes to match your lighting requirements. You can use them anywhere outdoors. Basically, they use the energy that the sun radiates during the day time. There is a different mAh that is available for every light solar. The higher the mAh, the longer the duration. Commonly, they have an average of 8 hours per day. You may start with that and see whether or not you need more or you need less.