Solar plant faults can occur at any stage throughout the lifetime of the plant and for many different reasons. Faults mean that the solar plant is producing less power than expected. When a solar plant is not working properly then the plant owner or investor loses money. Solar-Log® can help protect the investment by detecting solar plant faults.

Solar-Log® aggregates data from over 2,300 components including over 100 inverter brands. Through internal calculations, Solar-Log® can trigger performance analysis and alerts based on a normalized view.

Solar Panel Orientation, Pitch and Azimuth

Detecting solar plant faults can be done by comparing the output of the inverters. The challenge with this is that the strings connected to the inverters might be set at different angles or pitch. For example, there might be solar panels on the east side of the roof and other panels on the west side. The power output of these panels may be different because of the difference in orientation.

The output from panels with different orientation and pitch can be normalized by defining module fields. Each module field is made up of MPP trackers of the same module type, same angle, and same inclination.

The following image illustrates three MPP trackers connected to 1 inverter. In this example, MPP tracker 1 and MPP tracker 2 would be defined as one module field. MPP tracker 3 would be defined as a different module field because of the different orientation. The irradiance sensor in the graphic would also be configured in module field 2 because it shares the same orientation as MPP tracker 3.

Module fields can be set up in the same way if a solar array has panels on different rooftops or if it has a combination of mounting types like rooftop plus ground mount.

Inverters by Specific Yield – Detecting Solar Plant Faults

A second challenge with comparing inverter output is that the inverters may be different sizes. Fortunately, Solar-Log® can normalize the data from inverters so that the output of one can be compared to the output of another, even if they are different sizes. This is done through specific yield which is kW/kWp and is best explained through an example.

The next illustration shows 4 inverters, each of different sizes; 10kW, 8kW, 6kW and 2kW per string (2).

Inverter 1 is producing 5kW which the Solar-Log® defines as 50% of its power generation. The Solar-Log® continues to check the connected inverters, assigning a percentage value to the data in the same way it did with inverter 1. At 52%, inverter 3 is producing a higher percentage than the other inverters, so this inverter will be set as the reference for the power comparison.

Inverter 4 has two MPP trackers and two strings with 2000 watts. String 1 is producing 1000W. This is within the comparable range, around 50%. String 2, on the other hand, is producing only 500W which is only 25% or 0.25 kW per kWp. This large deviation in performance is an indication that there is something wrong with this string.

Solar Plant Performance Error Alerts

Solar-Log® users can choose to be notified of performance errors via e-mail. The email for the example above would state that there is a problem with string 2 on inverter 4, in module field 1. The reference inverter is inverter 3, and when compared to this inverter, it should be producing 1040 W. The current output of 500W is a deviation 48% between what it should be producing when compared to the percentage output of the other inverters.

In addition to comparing inverters, the output can also be compared to nearby plants or forecasted amounts determined by satellite weather data or onsite weather sensors.

It is important to note that the alerts will only be accurate if the portal is configured completely and correctly. Are you receiving several alerts from your Solar-Log® portal? Contact us and ask about our new configuration service.

Views from Solar-Log WEB Enerest™. Module field and inverter configuration:

 

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Suite 4A
Bethel, CT 06801
United States of America
Phone: (203) 702-7189
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