The first thing to note was that the panels were clearly dirty and the inverter and metering enclosures showed clear signs of wear.

On further inspection we identified several issues that were substantially affecting the performance of the system, with serious consequences for the financial return.

Inverter 3 not operating

The major concern is that inverter number 3 (SMA 15kW model) is not working. The display reads INSTALLATION FAILURE, indicating that the connection to the AC side is not correctly set up. On further investigation it became clear that the AC isolator switch did not appear to be working properly.

AC isolator switch

The AC isolator appears to have had a loose connection, which has led to overheating over time. This issue has reached the point where the connections have burnt out, meaning that the switch was not on and the inverter has been unable to deliver electricity to the AC connection. This switch will need to be replaced and we recommend checking all other terminations in the system to ensure they are connected correctly.

Meter cabinet has water ingress

Over time the waterproof seals on the meter cabinet have degraded to the point where water is able to enter and collect. This can cause various issues, including the potential for the system to partially of wholly shut down if protective devices trip. The seals around the edge of the cabinet have all been built up with dirt which appears to be absorbing water and allowing it to enter at the cabinet edges. These will need to be cleared out and the seals made watertight.

Earth connections

The earth connection at the bottom of the cabinet is of particular concern, since the water has already started to corrode the connection. This issue will need to be addressed.

Monitoring system

The monitoring system did not appear to be functioning, or indeed to have a working power supply. We recommend investigating this further, since we would have expected this system to alert the owner to the inverter issue outlined above.

Dirt on panel surface

There is a substantial amount of dirt on the surface of the panels and the generation could certainly be improved by cleaning them.

General cleanliness and air flow

The inverter enclosure has accumulated a lot of dirt, cobwebs and insect remains. Whilst these are not all necessarily causing direct losses, they will affect the airflow around the inverter units and may shorten their operating lifespan. We would recommend creating vents at the sides of the cabinet and thoroughly cleaning out the current dirt and cobwebs.