Power for larger features
A mains-powered ground light does not have to conserve battery power, so it can provide much more brightness. If you want to light up an entire façade, light a mature tree from bottom to top or highlight a pillar, mains power is the better choice. What is more, it provides the same brightness every evening, including in December.
Plan it during installation
That is the downside: a cable has to reach the right spot, and the spotlight has to be set into your paving or ground. This is by far the easiest to arrange when you are constructing your garden or carrying out a renovation. If your patio is already laid, you will need to lift the paving. So think ahead and lay some extra cable at the same time for places where you might want to add lighting later.
Drive-over or walk-over
If the ground light is going into a driveway or a path you walk on, check that the model is drive-over or walk-over rated. Not every spotlight can take that load. The product details state what each model is suitable for. Choose a robust version for a driveway if you want it to withstand regular use for years.
What to look for
Pay attention to the stated protection rating (IP rating): the spotlight sits in the ground, where water can collect. Some spotlights run on 12V and need a transformer. Use an underground power cable for cables that run underground, and have the connection carried out by a professional.