Reversing potential induced degradation at a Gujarat plant
Saur Energy article on solar diagnostics · 15 MWp plant, Gujarat
The situation
The plant showed potential induced degradation (PID), a loss that builds up when modules sit at high voltage relative to ground.
Background
PID can sometimes be reversed, but only if it is truly the cause. Applying a remedy to a plant whose loss comes from something else wastes money, so measurements before and after are important.
What was tested, and how that method works
A PID reversal device ran for 126 days. EL images were taken before and after.
PID shows up as weaker modules toward the negative end of strings. IV curves and EL images before and after a reversal show whether power and cell activity came back.
Our service: PID and degradation testing →What was found
- On the sample module, open-circuit voltage rose 12.55% and maximum power rose 29.91%.
- Average power rose about 9.03% compared with the level before reversal.
How it unfolded
Outcome
Separately, stricter O&M practices at the same plant added an average power gain of about 2%.
Lessons for a plant owner
- PID can sometimes be reversed, and before-and-after imaging shows whether it worked.
- The best-case sample result is not the plant-wide result. Look at the average.
- Good O&M practice added gains of its own, on top of the remedy.
Questions to ask about your own plant
- Are modules at the negative end of our strings weaker?
- What is our grounding and string-voltage arrangement?
- Do we have baseline IV and EL data to compare against?
How we would approach a similar site
We would confirm PID with IV curve tracing and EL imaging on a sample before recommending any remedy.
The sample-module gain is not a plant-wide result. Figures are as reported in the article. Source: Saur Energy. Summarised in our own words.