Grid Connected PV Systems – Sizing Exercise

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Grid Connected PV Systems – Sizing Exercise

Albert Tur Costa

Solar Photovoltaics – Fall Semester 2018

Professor: Santiago Silvestre

All the calculations had been performed using an Excel file. The Excel file is also attached at the delivery Task.

1. Calculate the value of the average annual PSH at the PV system site.

First of all, the value of the average annual PSH at Girona is calculated. Using the data provided at Table I and dividing the value of monthly specific irradiation between the days of each month, PSH are calculated for each month. The average annual value can be calculated dividing the total annual specific irradiation between the total number of days in a year (365). The results are shown at next Table.

Table 1.- PSH calculations.

The average annual value of PSH is 3,88 hours/day.

1. Estimate the number of PV modules to include in the PV array.

The total number of PV modules to include in the PV array is calculated quite straightforward. The peak power in DC of the array is a known value, 9,3 kW. Also, the peak power of each PV module, 155 W.

So:

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The number of PV modules to install is 60.

1. Give the PV array modules configuration: Ns and Np.

In order to determine the correct configuration of the PV array it is necessary to perform different calculations to ensure the correct performance of the PV array and the inverter.

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Figure 1.- Number of parallel modules to be installed (Maximum value). [1]

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Figure 2.- Inverter voltage threshold, considering number of series modules installed. [1]

That calculations are done taking into account the parameters of the inverter (Table III) and the parameters at MPPT conditions of the PV module (Table II).

Performing the calculations, it is observed that different PV array configurations are possible, as the inverter has a threshold for the Voltage in MPPT.

Table 2.- Different possible PV array configurations.

Highlighted in green, the most suitable configurations are shown. Knowing that the voltage threshold of the inverter at MPPT conditions is between 200 V and 800 V, it is selected the configuration formed by 15 modules in series and 4 strings of modules in parallel (Ns= 15; Np=4).

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