The duration of solar panel installation can vary depending on several factors, including the size of the solar panel system, the complexity of the installation, the location, and weather conditions. Generally, the installation of a standard residential solar panel system can take anywhere from a few days to a week. Here are some important considerations:

1. System size: Smaller solar panel systems for residential purposes can generally be installed more quickly than larger systems. The number of panels and the total capacity of the system affect the installation time.

2. Roof type and configuration: The type of roof (pitched, flat, bitumen, etc.) and its configuration can influence the installation time. Pitched roofs with a simple configuration are often faster to install than more complex roofs.

3. Preparatory work: Any preparatory work, such as reinforcing the roof, can take additional time. This is especially relevant if the roof needs to be adjusted to support the extra weight of the solar panels.

4. Electrical work: The electrical wiring and connection to the grid also require attention. This may take extra time, especially if adjustments to the building's electrical system are needed.

5. Weather conditions: Unpredictable weather conditions, such as rain or extreme heat, can affect the installation time. Installers often have to wait for suitable weather to work safely.

6. Inspections and permits: The time required for inspections and obtaining the necessary permits can vary depending on local regulations.