Two weak inverters found by tracking daily efficiency
Saur Energy article on solar diagnostics · 5.75 MWp plant, Rajasthan
The situation
The plant was underperforming and the inverters were suspected.
Background
With several similar inverters on the same plant, weather and sunlight are the same for all of them. A difference in efficiency is therefore likely to be the equipment rather than the day.
What was tested, and how that method works
Daily inverter efficiency data from 7 inverters, tracked over 18 consecutive days.
Collect the daily efficiency from each inverter on identical days, then compare. Units that are consistently below their peers are flagged for on-site checks of cooling, terminations and firmware.
Our service: Inverter diagnostics →What was found
- Two of the seven inverters underperformed the others.
How it unfolded
Outcome
After the weak inverters were replaced and a claim was made on the manufacturer, the plant gained about 1% in performance.
Lessons for a plant owner
- Comparing similar inverters side by side over a few weeks can show which unit is the weak one.
- A small percentage on a multi-megawatt plant is still meaningful income over years.
- Data already sitting in the monitoring system is often enough to start with.
Questions to ask about your own plant
- Do we have the daily efficiency of every inverter, not just the plant total?
- Which inverters trip or derate more than the others?
- Are any inverters still under warranty?
How we would approach a similar site
We would collect inverter logs, compare units on the same days, and confirm on site with electrical checks.
Figures are as reported in the article. The plant owner is not named. Source: Saur Energy. Summarised in our own words.