Solar panels are rated for their efficiency in a lab setting. In the real world, there are numerous factors that affect a panel’s efficiency.
- the array’s orientation
- your roof’s pitch
- any obstruction of even a portion of the panel by shade
- panels need to be hosed off on occasion as a panel’s efficiency can be slightly ower if it accumulates too much solid dirt such as bird droppings, mud
- panels typically require a bit of air flow underneath them to avoid extreme heating conditions