At the time of this writing, there is no set industrial standard regulating how long solar lights will stay on at night. Individual performance is set by manufacturer and environmental conditions. However, generally speaking, solar lights can be expected to stay on anywhere from six to twelve hours.
Always check for advertised time when considering a purchase.
Solar Lights & Designed Performance
There are three main variables that engineers can control when it comes to your solar light. Your light will stay on depending on how these three variables are factored in relationship to each other.
These variables are:
- Solar Cell – the size of this component determines the amount of electricity that can be produced over the course of a day.
- Battery storage – the size of this component determines the amount of electricity that can be stored.
- LED – the size and the number of this component determines just how much electricity is consumed over night.
If you have the right combination of these three variables, then your light can stay on a long time. But if there is an imbalance, say for example, you have a medium-sized solar cell and a medium-sized battery storage unit, but a large number of LED’s, then your light will not stay on long.
Likewise, if you have a large solar cell but a small battery, then the LED’s will have a limited amount of energy to use and your light will not stay on very long.
While the engineering of this critical balance is fairly straight forward, designers are often challenged by a limit of components available relative to the design requirements that have been placed upon them.
# Note #
A good look at customer reviews can help you know which outdoor solar lights were designed with performance in mind. (Beware the lights that DON’T advertise how long they will operate).
Solar Lights & Environmental Conditions
Solar cells need direct sunlight in order to produce electricity at their best. They will produce power in cloudy conditions, but it will be at a reduced rate.
As to how much your particular solar light will be impacted by less than optimum conditions, depends on how well the light was manufactured.
If the light was designed well, with its’ components well balanced, your solar light should stay on at night even if the amount of sunlight was less than desirable.
However, if the light was not designed well, then a lack of sunlight is certain to be noticed.
If you find yourself in this position, you could try cleaning the solar cell (dust and pollen can greatly reduce power output) or you could consider moving the solar light to a location that gets more sunshine.
Solar Lights: Summer Vs. Winter
For some places where snowfall is heavy, having solar lights outdoors is not really an option. However, for those blessed with sunshine all year round, you may notice a difference in how long your lights stay on at night.
As mentioned above, solar cells work best with direct sunlight. And as our planet actually tilts from season to season, then the angle of the sun is always changing.
With the majority of solar lights having their solar cells positioned horizontal to the ground, this seasonal tilting can impact the amount of electricity your lights’ solar cell can produce.
To understand this, think line of sight.
For example, when the sun is high in the sky, then the sunlight is striking directly on the solar cell. But as the sun hangs lower in the sky, much like it does in the winter, then the photons present in sunlight are not hitting the light directly as much as striking it on an angle. This will decrease power output from your solar cell.
Also, the sun tends to shine longer during the summer, increasing the amount of exposure time your solar lights needs in order to produce power.