Testing services on grid connected PV systems according to the requirements set by IEC 62446. The tests include system documentation and verification of DC and AC side protection, insulation and performance.
The module under test is installed outdoors on an open-rack mounting at 45 ° inclination, with temperature sensors attached to the rear of the module. The module is left open-circuited, and its temperature is measured every five seconds, along with wind speed and direction, irradiance in the plane of the panel, and ambient temperature. This data is then processed to indicate the operating temperature of the panel under 20 °C, 800 Wm-2 irradiance. Three clear days with low wind speed are typically needed for this test to take place. A test report is prepared in accordance with ISO 17025.
For the outdoor performance test, 1-3 modules are installed outdoors and connected in series. Temperature sensors are connected to the rear of the modules, and they are subjected to regular current-voltage characterisations, once every 1- 5 minutes. Performance indicators such as short-circuit current, open-circuit voltage, maximum power point and fill factor are stored in a database along with a full array of environmental data. At regular intervals, the modules are subjected to a ‘flash test’ characterisation indoors, to provide performance benchmarks, performed alongside a control module kept indoors. A test report is provided every three months.
In the energy yield test, a 1 kWp system is mounted on an open rack, fixed at the optimum inclination for photovoltaic systems at the PV Technology test site and connected to the grid through an inverter. The inverter holds the system at its maximum power point. The DC and AC energy yields of the system are monitored and logged at high resolution over a year, alongside the module operating temperatures, irradiance and environmental conditions. This provides all the information required to calculate the performance ratio of a system. The option to regularly perform an indoor flash of one module is also offered. A test report is provided every three months.
A combination of the two outdoor system tests provides a complete understanding of the behaviour of a PV system and is particularly suitable for degradation studies. In the combination test, a 1 kWp PV system is installed at the UCY test site, and alongside this an additional 1-3 modules are installed. The additional modules are subjected to regular I-V characterisations, but kept at open-circuit between measurements. At regular intervals, a module from the 1 kWp system and a module from the additional set are flashed indoors next to a control module that is kept indoors. A test report is provided every three months.