Low PV voltage

  • I have a new 3.9kW 20 -195W panel system. My inverter reads PV output 84V in direct sun. I checked the control panel with a meter before & after fuses. 3 of 5 circuits ( 5 circuits , 4 panels each in series) reads ~84V in full sun. 2 of 5 are 0 V. I understand I need to troubleshoot each panel in the 0 V circuits as a panel(s) in each series may be bad.  However, shouldn't the Voltage on the inverter be reading 84V+84V+84V or 252V? Is this an inaccurate calculation. Any other thoughts? Thanks

  • Four panels connected in series will give you about 84VDC in full sunshine with no load.  If you connect these four panels in parallel to another set of four series connected panels, the overall output voltage will remain 84V.  If you do that three more times, you'll have 5 sets of four series connected panels delivering 84 VDC to your inverter.  I hope all of that makes sense :)

    You will only measure 84VDC if the panels have no load on them.  Once a load is added, this voltage will drop closer to 48VDC and this is totally normal.  The load could simply be the batteries being charged by your system.

    You don't mention what kind of inverter you have.  But im guessing you have a 3500W/48VDC inverter.  What is the display on your inverter showing?


  • A low PV (Photovoltaic) voltage typically refers to a situation in a solar power system where the voltage generated by the solar panels is lower than what is expected or required. This can occur for various reasons and can have implications for the performance and efficiency of the system. Here are some common causes and consequences of low PV voltage:

    Causes of Low PV Voltage:

    1. Shading: When solar panels are partially shaded by objects such as trees, buildings, or debris, it can lead to a reduction in voltage output. Even a small amount of shading on a single solar cell can significantly impact the voltage of an entire panel.

    2. Dirt and Dust: Accumulation of dirt, dust, or other debris on the surface of solar panels can reduce their ability to generate electricity, resulting in lower voltage output.

    3. Mismatched Panels: In a solar array, if one or more panels are mismatched or damaged, they may generate lower voltage than the rest of the panels.

    4. Aging Panels: Over time, the efficiency of solar panels can degrade, leading to lower voltage output compared to when they were new.

    5. Temperature: Solar panels are sensitive to temperature, and extremely high temperatures can lead to a decrease in voltage output.

    6. Inverter Issues: Problems with the inverter, which converts DC (direct current) voltage from the panels into AC (alternating current) for use in your home, can result in lower voltage.

    Consequences of Low PV Voltage:

    1. Reduced Power Output: Low PV voltage directly translates to reduced power output from the solar panels. This means that your solar system will produce less electricity, potentially affecting your ability to meet your energy needs.

    2. Inefficiency: An underperforming solar system can be highly inefficient, meaning you won't maximize the return on your investment in solar panels.

    3. System Shutdown: In some cases, if the voltage drops too low, it can cause the inverter to shut down for safety reasons to prevent damage to the system.

    4. Reduced Savings: Lower electricity generation from your solar panels may result in reduced savings on your energy bills.

    Addressing Low PV Voltage:

    To address low PV voltage in your solar power system, consider the following steps:

    1. Regular Cleaning and Maintenance: Ensure that your solar panels are clean and free from shading, dirt, or debris. Regular cleaning and maintenance can help maximize their efficiency.

    2. Inspect for Damage: Check your solar panels for physical damage or signs of wear. Replace any panels that are damaged or underperforming.

    3. Inverter Check: Have your inverter checked by a qualified technician to ensure it is functioning correctly.

    4. Temperature Management: Some systems may benefit from temperature management solutions, such as cooling systems, to mitigate the effects of high temperatures on panel efficiency.

    5. Professional Assessment: If you continue to experience low PV voltage despite basic maintenance efforts, it may be wise to consult with a professional solar technician or installer to diagnose and address the issue. solar power system

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