Installation, Commissioning, Testing and Maintenance of Solar PV Systems
Installation, Commissioning, Testing and Maintenance of Solar PV Systems
This domain tests site practice: mounting, orientation, cable management, commissioning tests and preventive maintenance.
Core rules
- Mount modules with correct tilt and azimuth, clear of shade; keep minimum roof clearance for ventilation.
- Use DC-rated isolators, MC4 connectors, UV-resistant cables, and separate DC and AC conduit.
- Commissioning checks: polarity, open-circuit voltage per string, short-circuit current, insulation resistance, earth continuity, earth resistance, inverter parameters and anti-islanding.
- Maintenance: cleaning, thermal inspection for hot spots, torque checks, connector inspection, battery electrolyte and terminal checks.
- Record as-built string layout and serial numbers for fault tracing.
Worked example
A string has 10 modules with Voc = 40 V at 25°C. At 25°C string Voc = 400 V. The datasheet temperature coefficient is −0.3%/°C for Voc. At 15°C, the rise is 10 × 0.3% = 3%, so cold Voc ≈ 412 V. The inverter maximum DC input is 500 V, so the string is acceptable, but at −5°C the same calculation gives 436 V and still needs checking against the limit.
Traps that cost marks
Measuring Isc with the meter set to the wrong range or polarity; checking Voc only at one module instead of the string; ignoring cold-temperature Voc rise; using AC-rated switches on DC; cleaning modules while energised without precautions.