Project story · Boralesgamuwa
Finding the weak microinverter: a rooftop in Boralesgamuwa
Nimal's house in Boralesgamuwa has eight ReneSola 320 W panels on two APsystems microinverters, four panels each. One of the two units was producing about a third of what its twin did, at every level of sunshine. The per-unit data pointed at the cause, and one swap on the roof proved it.
Published
The system
- Place
- Boralesgamuwa, Colombo district
- System
- Grid-tied rooftop with microinverters, four panels per unit
- Solar
- 8 × ReneSola 320 W polycrystalline, 2.56 kWp
- Microinverters
- 2 × APsystems YC1000-3 with an APsystems ECU; one replaced on 11 September 2026 by a newer APsystems unit
- Fault isolated
- 23 August 2026
- Monitoring
- Per-microinverter data from the APsystems ECU, analysed by KTronics
One unit at a third of its twin
Microinverters report each group of panels separately, so the two halves of this roof could be compared directly. One unit was producing about a third of its twin's output, in weak sun and in strong sun alike. With the same panels on both, the shortfall was either in those four panels or in the microinverter under them.
The swap that settled it
On 23 August 2026 we swapped the two panel groups between the units. The shortfall stayed with the same microinverter, which cleared the panels. The cause was a failed DC input stage: the unit could draw only about 1.9 A per input, against 7.5 to 9 A on the healthy unit.
The unit was replaced on 11 September 2026 by a newer APsystems unit on the same four panels. Since then it has produced slightly more than its twin.
Still on the watch list
Two things from the same data stay on the watch list.
- The grid voltage at the site peaks at 259 V, above the 253 V ceiling. That is for the utility to correct.
- The remaining original microinverter runs hotter than the new one.
Related pages
More projects
Installations and equipment, photographed on site, and the other project stories.
Read more →Service and support
What we commit to after handover, and what monitoring does and does not catch.
Read more →IoT monitoring platform
Monitoring and control built around the equipment a site already has.
Read more →Site assessment
A system producing less than it should?
Tell us what the monitoring or the bill shows, and whether we installed the system or someone else did. We service both.