Plant Array Nominal Energy

The plant array nominal energy is the baseline for the Conversion Effect calculations. This represents the annual energy yield of the array when the considering all reductions in irradiance described in Irradiance, but assuming that the modules are converting incident radiation into electrical power with the same efficiency that they achieve under the selected reference conditions (typically Standard Test Conditions, STC).

STC conditions are:

• Cell temperature of \(T_{\text{c,ref}}\) = 25°C (77°F)

• Incident light intensity of \(G_{\text{ref}}\) = 1000 W/m²

• Air mass of 1.5 (characterises the spectrum of the incident light)

The nominal efficiency of a module under Standard Test Conditions can be simply calculated as:

$$\eta_{\text{ref}} = \frac{P_{mod,nom,ref}}{A_{\text{mod}} \times G_{\text{ref}}}$$

Where:

• \(P_{\text{mod,nom,ref}}\) is nominal electrical power of module under reference conditions (generally obtained from the module datasheet);

• \(A_{\text{mod}}\) is module area;

• \(G_{\text{ref}}\) is the reference irradiance, equal to 1000 W/m² under STC.

Therefore the power produced by submodule j at time t in the array under the effective incident irradiance \(G_{\text{eff}}(j,t)\) but holding the module efficiency equal to the nominal efficiency under reference conditions would be:

$$P_{submod,ref}\left( j,t \right) = G_{\text{eff}}\ (j,t)\ \times A(j) \times \eta_{\text{ref}}$$

The Plant Array Nominal Energy is then:

$$E_{Parray,nom} = \sum_{t}^{}{\sum_{j = 1}^{N_{\text{submodules}}}{P_{submod,ref}\left( j,t \right) \bullet \Delta t}}$$

This could be summed over any period, e.g. annual, monthly etc. The result will need to be de-seasoned when creating and annually-representative number from non-annually representative input data (i.e. not using TMY files).