6 Tips to Troubleshoot When Your Off-Grid Solar System Stops Working

When an off-grid system goes down, it is often challenging to know what to do next. Our technical team has put together a list to help you diagnose the problem so you can get your system back up and running.

Understanding what is wrong will help you save time and money, no matter what the problem is. The key is to look at all aspects of your system and avoid assuming anything when troubleshooting. These valuable tips and common problems will jump start your solution.

1. Check all wires, connections and fuses.

• Tighten screw terminals. They can loosen over time due to corrosion, freezing and thawing cycles, or from vibration in transportation or RV applications.
• Check for reverse polarity connections. There are sometimes no warning indicators.
• Check terminal and wire labels or use a voltmeter.
• Replace blown fuses, corroded wires or terminals, and any wires exposed from insulation abrasion.

2. Check indicator LEDs or LCD icons on your charge controller.
Most charge controllers have helpful indicators to diagnose problems. Check the product manual if you need help identifying what a message means. This could quickly get you to a solution. Low Voltage Disconnect (LVD) is a common error when an off-grid solar system is down. Check the battery voltage to verify, or when available, check a controller datalogger for the telltale sign of greater energy used by loads than energy going to charging batteries. Potential causes include:

• Lack of sun to recharge the batteries.
• Battery capacity reduced in cold weather.
• Load working longer than designed.
• More load added than original design specifications.

3. Check the solar panel’s access to the sun and if the solar panel is performing properly.
Pay attention to parameters that can impact performance and energy production:

• Clean panels. Dirty panels can lead to significant loss of energy production.
• Check for burned out solar cells.
• Check junction boxes for damage such as loose wires, corrosion, or blown diodes.
• Remove shade. If 10% of a solar panel is shaded that does not mean you should expect 10% less output. Cell stringing will cause a much higher percentage of lost production.
• Use a digital multi-meter to check the open circuit voltage of each individual solar panel and compare the data with the manufacturer’s datasheet for your PV module to help confirm performance is as designed.

4. Check battery performance.

• Take your batteries to a professional to have them tested.
• Compare battery operating specifications to weather data to determine if extreme weather is impacting performance.
• Battery specifications can be found on the product datasheet or manufacturer’s website.

5. Re-check design parameters.
Extreme weather conditions can exceed original design parameters and cause poor system performance.

• Check worst-case sun hours for your region and compare to design parameters.
• Check battery capacity days with no sun and compare to design parameters.
• Review calculations with today’s load usage and weather conditions. The original design may not account for extreme weather conditions or added load.
• Confirm tilt angle is ideal all year with consideration to azimuth.
• Re-evaluate losses throughout a system:
  • Voltage drops and power losses can be minimized with larger wires.
  • If there is an inverter in the system, confirm its energy consumption was factored into calculations. 

6. Check appropriate ventilation to prevent overheating.
Electrical equipment can overheat and temporarily shut down. Inverter(s) might shut down without adequate ventilation. Controllers might limit charge current more than expected due to heat. To address overheating:

• Check product manuals for guidelines on correct mounting style, spacing and ventilation.
• Clean system equipment and vents to remove dirt and debris that interferes with ventilation.
• Assess if space and ventilation in enclosures are appropriate.
• Keep equipment out of direct sunlight for best performance.