Recent sun photometers are automated instruments incorporating a sun-tracking unit, an appropriate optical system, a spectrally filtering device, a photodetector, and a data acquisition system.
A third-party data acquisition system can monitor multiple inverters, using the inverter manufacturer's protocols, and also acquire weather-related information.
Various methods are employed for data acquisition: direct interviews, more or less automated observation, analyses of administrative data, complete enumeration surveys and representative sample surveys.
These instruments are typically low-power (12 volts), are often used in remote locations, and usually communicate with a data logger or other data acquisition device.
