If solar panels fail or if you notice that the energy output suddenly decreases, there are several steps you can take to solve the problem. Here are some suggestions:

1. Visual inspection: Visually check for any visible issues, such as damage to the solar panels, loose wiring, or problems with the mounting system. Keep safety regulations in mind and only go on the roof if you are skilled in such tasks.

2. Check the inverter: The inverter is an essential part of the solar panel system. Check if the inverter is on and if there are any error codes displayed. Consult the inverter manual to interpret any error codes.

3. Consult the monitoring system: If you have a monitoring system installed, review the data to see if there are any unusual trends or warnings appearing. Some systems may even automatically alert you to problems.

4. Check for shading: Ensure there are no new obstacles casting shadows on the solar panels. Shading can significantly reduce energy output.

5. Check the safety switch: Some systems have a safety switch that can be activated in case of malfunctions. Check if it is on.

6. Technical support: If you're unable to solve the issue yourself, contact the solar panel system installer or a qualified professional for technical support. They have the expertise to resolve more complex issues.

7. Warranty terms: Check the warranty terms from the manufacturer and installer. If the solar panels are still under warranty, the repair may be carried out at no cost.

It's important to be cautious when performing inspections and any repairs. If you're unsure about what to do, it's always best to seek professional assistance. A qualified installer can diagnose the problem and take the necessary steps to get the solar panel system functioning optimally again.