Global Sustainable Energy Solutions (GSES) has released a technical white paper, entitled Oversizing PV Arrays, to address issues faced when designing photovoltaics (PV) systems so that the array has a higher peak capacity than the inverter.

Owing to the recent decreasing cost of PV modules, oversizing of PV arrays has become an economically viable way to increase system output, and GSES has received several requests for information on this. However, care must be taken when designing such a system, as incorrect calculations could lead to overloading of the system, with potentially dangerous results.

As detailed in the article, “Some inverters can protect themselves from currents greater than their specified range, but all inverters will be damaged from open circuit voltages above their specified range. Before designing an oversized array, assurance, preferably in writing, must be gained from the inverter manufacturer that their equipment is suitable for this application and that using the inverter in this way will not void the warranty.”

Regarding the pros and cons of oversizing, the article states, “By oversizing the array, the system will produce more power in the morning and evening, and during other times of low solar irradiation. In effect, this will increase the amount of time that inverters are operating at their nameplate capacity. The downside of oversizing is that when solar conditions are favourable, the output of the array is ‘clipped’ and potential energy from the system is lost.”

GSES director Susan Neill says of the article: “It is essential that system designers understand the limitations of oversizing the solar array and how this affects the performance and economics of solar systems.”