PM compliance (conversion rate)
PM compliance = PM tasks completed ÷ PM tasks scheduled (same period)
Measure it per plant, per equipment type and per frequency (daily, weekly, monthly, quarterly). A portfolio average can hide one plant that has quietly stopped doing PM.
Worked example · illustrative numbersComparing plants
| Plant | Scheduled | Completed | Compliance |
|---|---|---|---|
| Plant A | 2,400 | 2,376 | 99.0% |
| Plant B | 1,920 | 1,855 | 96.6% |
| Plant C | 2,100 | 1,560 | 74.3% |
| Plant D | 1,400 | 0 | 0% |
Plant D isn't failing at PM; it has almost certainly stopped recording it. Either way, it needs a call today.
Planned vs actual
Compliance tells you how much was done. Planned versus actual tells you when. A calendar view by equipment type and day shows whether monthly tasks are bunched into the last few days, which usually means they were rushed.
Backlog and skipped work
- Backlog: tasks past their due date and not done. Track the count and the age.
- Skips: sometimes a task genuinely can't be done (no manpower, monsoon, access). A skip should be requested, approved by someone accountable, and recorded, not silently dropped.
- Recurring skips on the same equipment are a warning sign worth reviewing monthly.
MTTR and MTBF
| KPI | Formula | What it tells you |
|---|---|---|
| Mean time to repair (MTTR) | Total repair time ÷ number of repairs | How fast the team restores equipment |
| Mean time between failures (MTBF) | Total operating time ÷ number of failures | How reliable the equipment is |
| Mean response time | Time from alert to acknowledgement | How quickly someone takes ownership |
Good PM should push MTBF up over time. If PM compliance is high but MTBF isn't improving, the PM plan may be checking the wrong things.
What a solar PM plan typically covers
- Module cleaning and visual inspection
- Inverter inspection, filter cleaning and thermography
- SCB and string checks, fuse and connector inspection
- Transformer and HT panel inspection
- Earthing and lightning protection tests
- Weather station and sensor cleaning and calibration
- Vegetation control, drainage and civil works
- Security, lighting and fire systems
How nxtGrid helps
How nxtGrid helps
- Central CMMS dashboard with PM status and conversion rates across all plants
- PM schedule calendar showing planned versus actual by equipment type and day
- PM summary by equipment and side-by-side plant KPI comparison
- Daily checks, work orders and an approval workflow for skipped or rejected work
- Field app with checklists, photos and readings