Understanding name plate specifications of a PV module
The nameplate on the individual PV modules shall carry the following minimum information:
• Name and logo of the original manufacturer or supplier
• Type designation and serial number
• Maximum system voltage
• Rated nominal power (Pmax) at STC (1000 W/m², 25°C cell temperature, and air mass [AM] 1.5 global spectrum)
• Maximum negative production tolerance (- % or ± %) of Pmax at STC
• Rated nominal short circuit current (Isc), open-circuit voltage (Voc), the voltage at maximum power point (Vmax), and current at maximum power point (Imax) at STC.
Every solar panel should have a sticker in the back which tells you the VOC – voltage open circuit, and the LOAD voltage. The load voltage is what the panel produces when you are using power from it. The VOC is the no-load voltage and inverters etc have to be designed with a maximum input voltage greater than the VOC so they are not damaged by that slightly higher voltage when there is no power being used
The nominal power is the nameplate capacity of photovoltaic (PV) devices, such as solar cells, modules and systems, and is determined by measuring the electric current and voltage in a circuit, while varying the resistance under strict conditions. This nominal power is important for designing an installation in order to correctly dimension cable and converter requirements.
The peak power is not the same as the power under actual radiation conditions. In practice, this will be approximately 15-20% lower due to the considerable heating of the solar cells. The capacity of the power plant after DC-AC conversion is usually reported in WAC as opposed to Wp or WDC.