Sadly, it isn’t possible to give an accurate figure here, as there are a variety of factors at play. Of course, principle among these is the amount of charge received by the solar light. The batteries are not the same on all solar lights though and some may have more capacity than others, meaning two lights given the same exposure to the sun may run for different lengths of time. Those solar lights incorporating larger, higher quality panels are also more likely to absorb the sun’s rays more efficiently, giving these lights a competitive advantage.
Our advice is to follow our solar lights best practice to maximise the performance from your lights. If performance is your main consideration, opt for one of the more costly lights as these usually have better components and therefore longer, more consistent performance.