Potential PV Problems: Page 3 of 3

& New Tools for Troubleshooting
By: 
Justine Sanchez
Issue Date: 
June / July 2011
Last Updated: 
12/20/11
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Inside this Article

Cleaning PV modules on a flat roof.
Solar technician cleaning an array on a flat roof. A perfect place for dust to settle and block the sun.
Comparing clean and uncleaned modules
Soiling is not always obvious until you start cleaning, but it can reduce PV module output significantly.
Weeds growing because of pigeon droppings
A failed attempt at keeping pigeons from nesting under a PV array: Not only did weeds grow from the droppings, shading the array, but some of the screen has come loose and contributes to shading, too.
Bird and rodent protection, before modules installed.
Bird spikes, placed on the rack before the modules are mounted, effectively keep birds from roosting on and soiling modules.
Cell delamination
This module suffers from delamination between the glass encapsulant and several PV cells. The cell to the upper left also appears to have moisture-induced corrosion.
Broken cell in module.
Sometimes, module defects, such as this broken cell, can be spotted before the module is installed.
Burned cells in module
The bus bars and cell interconnects on this module have high electrical resistance, leading to extreme hot spots and actual burns on the bus bars, interconnects, and even on the polymer back sheet (not shown).
Cracked module
Cracked glass encapsulant allows water intrusion, which can cause corrosion and even a shock hazard.
Flir infrared camera
An infrared camera can be a handy tool in troubleshooting PV module problems.
Cleaning PV modules on a flat roof.
Comparing clean and uncleaned modules
Weeds growing because of pigeon droppings
Bird and rodent protection, before modules installed.
Cell delamination
Broken cell in module.
Burned cells in module
Cracked module
Flir infrared camera
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Growing Pains & Array Performance

Much of the current photovoltaic industry has focused on reducing the cost per installed watt, which, over the last five years, has dropped—from $10 per watt to between $5 and $6 per watt. This, coupled with incentive programs at the federal, state, and local levels, has resulted in the rapid deployment of grid-tied PV systems on homes and businesses across the country. However, it is possible that the swift ramping up in PV module production to meet this demand may be the source of some of the internal module problems discussed here. The good news is that monitoring options can alert us to problems as they arise, helping system owners maintain their systems and allowing module manufacturers to see their products’ performance over a wide range of installations.

Whether you are interested in maximizing your economic return or you simply want to generate as much renewable energy as possible, plan to periodically check your system’s output and watch for potential problems. Catching these issues early can keep you from losing precious sun-generated kWh for years to come.

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Justine Sanchez is a NABCEP-certified PV installer, Home Power technical editor, and Solar Energy International instructor who is now happily watching her new PV modules kicking out the expected watts.

Special thanks to Jeff Krisa and Stuart Davis of Tigo Energy; Jim Heneghan at DMEA; Colin Mitchell and Monali Joshi at Suntech; Gary Handelin of Solar Independence; Bill Brooks of Brooks Engineering; and Jeff Tobe and Kris Sutton of SEI.

Troubleshooting Tools:

FLIR • www.flir.com • Infrared cameras

Fluke • www.fluke.com • Infrared cameras

Solmetric • www.solmetric.com • PV Analyzer

Module-Level Monitoring:

eIQ Energy • www.eiqenergy.com

Enphase Energy • www.enphaseenergy.com

Exceltech • www.exeltech.com

SolarEdge • www.solaredge.com

Tigo Energy • www.tigoenergy.com

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