Low risk
The system still runs, but the numbers are well below what the same month used to give you.
Caution
The box on the wall is showing an error, a red light or a blank screen, and generation has stopped.
The panels are generating and exporting, but nothing is being credited for what leaves the house.
Scratching and cooing overhead, droppings down the wall, and a mess of nesting material under the array.
High risk
Damp on a bedroom ceiling or a stain in the loft that was not there before the array was installed.
The battery sits at a low percentage all day, or fills up and is flat again before breakfast.
A green or black band has built up along the bottom edge of every panel and nothing rinses it off.
The sun is out, the array is on the roof, and the house is as dark as everyone else's.
There is an array on the roof, an inverter in the loft, and nobody can tell you who fitted it or who owns it.
Emergency
A hot, acrid smell near the inverter, browning around a switch, or an isolator that is warm to the near touch.
Describe the job and get a fixed price from a local solar installer.
