MPPT failure

This troubleshooting guide addresses a situation where your Autarco inverter displays low or no DC voltage readings, indicating a problem with the Maximum Power Point Tracking (MPPT) system. Without proper MPPT function, your solar panel system cannot efficiently convert sunlight into usable electricity, leading to reduced energy output.

Possible Causes:

• Faulty or loose DC wiring connections between the panels and the inverter.
• Malfunctioning or shaded solar panels.
• Internal issues within the MPPT circuitry of the inverter.

Issue creation in Helios

A MPPT issue is created in Helios if: 

• an inverter has one or more MPPTs with average voltage below 30V or,
• average current below 0.1A during peak solar hours (11:00 AM to 1:59 PM) from the previous day's readings.

• all previously failing MPPTs return to normal operating parameters with voltage above 30V and,
• current above 0.1A during peak solar hours (11:00 AM to 1:59 PM) from the previous day's readings.

An MPPT issue in Helios (and therefore the notification in MyAutarco) disappears once the system has been operating as expected for more than 24 hours.

Before you begin:

Gather Information: Before starting troubleshooting, have the inverter manual on hand. You should also gather information about the inverter model and serial number, the installation date, and the PV array configuration (number of panels, capacity, and number of strings).

Troubleshooting steps:

1. Check DC Switch: Ensure the DC switch on the inverter is turned ON. Make sure you switch OFF the DC switch for step 2 to 6 in this troubleshooting guide.
2. Visual Inspection: Carefully inspect all DC wiring connections from the solar panels to the inverter, checking for any loose connections, damaged wires, or signs of corrosion.
3. Tighten Connections: If any loose connections are found, carefully tighten them, ensuring a secure and proper connection.
4. Check for Shading: Inspect the solar panels for any shading issues. Even partial shading on a single panel can significantly affect the performance of the entire string. If shading is present, try to eliminate or minimize it if possible.
5. Measure PV String Voltage: Verify the Open Circuit Voltage (VOC) of each PV string by measuring the voltage from the connector end after disconnecting the string from the inverter. Make sure the DC switch is turned OFF before you disconnected the strings from the inverter.
6. Check Voltage Trend: Utilize a multimeter to measure the voltages between PV+ and earth, as well as PV- and earth for all the PV strings. The voltages should exhibit a decreasing trend, falling within the range of 5% to 95% of the Voc (Open Circuit Voltage) of a single PV module.
7. Restart Inverter: If the above steps don't reveal any obvious issues, try restarting the inverter. Turn off both the AC and DC disconnects, wait for 5 minutes, and then turn them back on.

Verifying the solution:

After completing the troubleshooting steps, monitor the inverter's display for DC voltage readings. You should see appropriate voltage levels for each MPPT input, indicating that the system is functioning correctly. Additionally, check the energy generation in the MyAutarco app to ensure it has returned to normal levels.

If the problem is not resolved:

If the error persists after following all the above steps, there might be an internal fault within the inverter.

As a system owner: Contact the inverter installer or distributor for further assistance. You can find the details of your installer in the MyAutarco app.

As a certified installer: Contact Autarco Support. You can submit a support case via Helios.