As the rate of decline of the cost of the hardware for a solar PV plant is decreasing, solar plant designers are trying to find new ways to reduce the cost of production per KW using design innovation. The latest innovation in the matter is plant oversizing. This is becoming an integral part of the design process of new solar PV plants.
Traditionally design process was driven by the goal of achieving the highest specific yield (kWh/kWp) for a particular plant installation. DC to AC DC ratios have been traditionally ranging from 1.1-1.2. Now, some solar designers are targeting 1.5 or even higher. The result is a more stable production for the plant. In addition, oversizing helps to increase the plant capacity when there is a limit on the connection possibilities.
The projects can deliver higher IRRs for the investment in the installation. With lower PV module prices, the incremental cost of adding additional DC capacity to a system has greatly decreased. Since a larger array feeding a fixed size inverter will result in greater system annual production, the increased annual energy harvest is spread across the system’s fixed/semi-fixed costs, which include inverters, AC collection system, permitting, interconnection fees, engineering, and overhead. As a result, project financials have shifted in favor of increased Array-to-Inverter ratios.
The scales tip even further in favor of oversizing when considering time-of-use (TOU) utility rate structures, which place the greatest monetary value for energy delivery in the afternoon during summer months. Through oversizing, systems produce greater energy when energy has the greatest value.