Why aren't my solar lights working? 5 easy fixes, plus why your lights should always face south

Solar lights are by far my favorite way to light a garden. They're easy to install, cheap to buy, and free to run because they're powered by the sun. The best festoon lights can be the perfect finishing touch to a patio or deck.

However, the most common criticism of solar lights is that they don't last. Many of us have bought solar lights on a whim for a summer and found that they stopped working after a couple of weeks. Not only is this frustrating, it also creates a lot of plastic waste.

But before you throw out your lights, there are a few things you can try. I spoke to an expert electrical engineer about how you can revive your solar lights, and he gave me these five simple tips on how to fix lights that appear to be broken.

1. Clean the solar panel

One of the simplest fixes for a solar light is one of the easiest to overlook. Your first step should be to clean the solar panel.

Electrical engineering expert Harish Krinshamoorthy told me 'Cleaning the solar panel can often fix solar lights. Dirt, dust, and debris can block sunlight from reaching the panel, reducing its ability to charge the battery and power the light.

'Use something soft and mild to gently clean the surface of the solar panel. You may also need to dry it thoroughly to prevent water spots.'

Harish Krishnamoorthy

Harish Krishnamoorthy, an offshore wind technology expert, is an associate professor of electrical and computer engineering at the University of Houston. He is a 2023 early-career research fellow in the Gulf Research Program (GRP) of the National Academies of Sciences Engineering and Medicine’s Offshore Energy Safety track.

2. Move the solar panel

The next simple solution is to move your solar panel. Solar panels are surprisingly sensitive, and a spot you think is perfect for a solar panel may not quite work. In my years testing solar lights, I've found that discreetly hiding a solar panel in a flowerbed doesn't work. As the sun moves across the sky, leaves and petals can cast shadows that limit the amount of sunlight getting to your solar panels.

Professor Krishnamoorthy has another tip: 'It may be preferable for the panel to be slightly tilted toward the general southern direction.' In the northern hemisphere, the sun is always in the southern half of the sky. It's not a huge difference, but your lights are facing towards the north, you could be making them inefficient.

3. Replace the batteries

If cleaning or moving the solar panel doesn't work, your next step is to check the batteries. Solar lights run off rechargeable batteries, and these can often be replaced.

Professor Krishnamoorthy told me that 'you may be able to replace the batteries in a solar light. Many solar lights typically use rechargeable AA or AAA batteries. When replacing them, make sure to use the correct type and capacity as specified by the manufacturer.' You can usually find inexpensive replacement rechargeable batteries - there are plenty of rechargeable batteries on Amazon, for example.

Once you have replacement batteries, professor Krishnamoorthy says to 'Ensure the new batteries are properly installed and be cognizant of the orientation of the batteries in the compartment.' This is another common fix.

4. Fix the light sensor

If none of the above work, you may need to try some more technical fixes.

Professor Krishnamoorthy says that 'Fixing a solar light sensor can be a bit tricky depending on the issue. First, ensure that the sensor isn’t obstructed by dirt or debris. If the sensor is clean and the light still doesn’t work, check for loose connections or wiring issues.

'In some cases, the sensor may be faulty and need to be replaced,' he adds. However, be careful with this - consult the manufacturer's instructions before you make any significant changes.

5. Dry out water damage

The final problem could be water damage. Solar lights are usually water-resistant, but if you buy cheap lights they're probably not completely waterproof. Unfortunately, water damage is usually irreparable.

However, you can try drying out all the components. Professor Krishnamoorthy suggests that 'For minor water ingress, you might be able to disassemble the light, dry it thoroughly, and reseal any openings.' However, he warns that significant water damage cannot be fixed this way, so you're better off buying replacement lights.

Solar light FAQs

Do solar lights work under a covered porch?

Solar works work under a covered porch, but only if the solar panel is placed in full sun.

Do solar lights keep deer away?

No, solar lights don't deter deer - chimes are more effective.

While solar lights are helpful, they're far from the only way to light your garden. For more ideas and help, take a look at our guides to where you can place outdoor lights to avoid light trespass, and the best ways to light a fire pit.