A range of monitoring equipment and data collection systems are available for grid-connected and off-grid PV systems. Monitoring system performance is invaluable for detecting under-performing and faulty equipment. In large systems, monitoring is essential, since undetected system failures or under-performance can lead to considerable revenue losses.
In a grid-connected PV system, energy output can be checked regularly at the meter or inverter. However, more detailed information is required to assist with fault finding.
Typical performance indicators monitored include:
- Power output of PV module arrays (with reference to solar irradiation levels).
- Battery state of charge over time in off-grid systems and back-up systems.
PV inverter display showing power output, 1302 W; daily energy output, 14.75 kWh; and total energy output since the system was installed, 196.42 MWh.
Radiation sensor at a solar power plant. Source: SMA Solar Technology AG.
Monitoring systems fall into the following general categories:
- Energy meters
- Monitoring integrated into equipment such as PV inverters, other inverters and solar charge controllers
- Equipment-specific monitoring, specific to particular PV inverters, charge controllers and battery inverters/inverter-chargers, with remote monitoring
- Monitoring systems that can be used with a range of system types, also with remote monitoring
Many companies offer remote monitoring services over the internet.