Among critical design parameters, the DC-AC ratio—the ratio of PV module capacity to inverter capacity—directly impacts a plant's energy yield, operational stability, and economic viability.
What is PV module capacity & solar inverter capacity ratio?
The PV module capacity and solar inverter capacity ratio are commonly referred to as capacity ratio. Reasonable capacity ratio design needs to be considered comprehensively in the light of the specific project.
Because the PV array rarely produces power to its STC capacity, it is common practice and often economically advantageous to size the inverter to be less than the PV array. This ratio of PV to inverter power is measured as the DC/AC ratio. A healthy design will typically have a DC/AC ratio of 1.25.
What is the DC/AC ratio of a PV array?
This ratio of PV to inverter power is measured as the DC/AC ratio. A healthy design will typically have a DC/AC ratio of 1.25. The reason for this is that about less than 1% of the energy produced by the PV array throughout its life will be at a power above 80% capacity.
The variation of annual inverter efficiency from the maximum annual value for a low efficiency inverter is 5.6% when the sizing ratio decreases from 1.3 to 0.8 and 3.6% when the sizing ratio increases from 1.3 to 1.8. It can be concluded that the optimum PV/inverter sizing ratio depends on inverter characteristics.
What is the sizing ratio of a PV system?
The sizing ratio (Rs) is defined as the ratio of the PV array capacity at standard test conditions (STC) to the rated inverter input DC power given as (1) R s = P PV, rated P inv, rated where, PPV,rated and Pinv,rated represent rated PV capacity and rated inverter input power, respectively. Fig. 1. Interactions of influences on PV system sizing.
Should PV array capacity be higher than inverter capacity?
Undersized inverter would reduce system cost without affecting much system output. A previous study has also shown that a PV array capacity 40% higher than inverter capacity would improve the economic viability of a PV system (Keller and Affolter, 1992).