A solar plant with a PV system has an average solar irradiance for the region of 1 kW/m?. The plant is in operation for 16 hours per day and for 300 days in the year. The efficiency of the PV system is 40%.

The useable annual AC electricity generated is 3 GWh while the solar panels generates 2,4 GWh during the year.
Calculate the:
9.1 performance ratio of the plant
9.2 solar power generated
9.3 surface area of the collectors.

1 answer

To calculate the requested parameters related to the solar plant with a PV (photovoltaic) system, we can use the following information:

  • Average solar irradiance: \( G = 1 , \text{kW/m}^2 \)
  • Operation time per day: \( t_{\text{day}} = 16 , \text{hours} \)
  • Days of operation per year: \( d_{\text{year}} = 300 \)
  • Efficiency of the PV system: \( \eta = 40% = 0.40 \)
  • Usable annual AC electricity generated: \( E_{\text{AC}} = 3 , \text{GWh} = 3 \times 10^9 , \text{Wh} \)
  • Solar energy generated by the panels: \( E_{\text{PV}} = 2.4 , \text{GWh} = 2.4 \times 10^9 , \text{Wh} \)

9.1 Performance Ratio (PR) of the Plant

The Performance Ratio (PR) is defined as the ratio of the actual output of a solar plant to the expected output from the system at standard test conditions, taking into account losses due to inefficiencies, temperature, and other factors.

\[ \text{PR} = \frac{\text{Actual Output}}{\text{Expected Output}} \]

Where:

  • Actual Output is the usable AC electricity generated (\( E_{\text{AC}} \)).
  • Expected Output is the energy that should be generated by the solar panels based on the solar irradiance, area, and efficiency.

First, we need to calculate the expected output:

\[ E_{\text{expected}} = G \times A \times t_{\text{year}} \times \eta \]

Where:

  • \( t_{\text{year}} \) = \( t_{\text{day}} \times d_{\text{year}} = 16 , \text{hours/day} \times 300 , \text{days} = 4800 , \text{hours} \)

To find \( A \) (the area), we can rearrange the formula to calculate energy generated, using the energy generated by solar panels:

\[ E_{\text{PV}} = G \times A \times t_{\text{year}} \times \eta \]

Solving for area \( A \):

\[ A = \frac{E_{\text{PV}}}{G \times t_{\text{year}} \times \eta} \]

Then, we can calculate the Performance Ratio (PR):

  1. Calculate \( t_{\text{year}} \):

\[ t_{\text{year}} = 16 \times 300 = 4800 , \text{hours} \]

  1. Calculate \( A \):

\[ A = \frac{2.4 \times 10^9 , \text{Wh}}{1 , \text{kW/m}^2 \times 4800 , \text{hours} \times 0.40} \]

\[ A = \frac{2.4 \times 10^9 , \text{Wh}}{1 \times 4800 \times 0.40 , \text{Wh/m}^2} = \frac{2.4 \times 10^9}{1920} \approx 1,250,000 , \text{m}^2 \]

  1. Calculate the expected output:

\[ E_{\text{expected}} = G \times A \times t_{\text{year}} \times \eta \] \[ E_{\text{expected}} = 1 , \text{kW/m}^2 \times 1,250,000 , \text{m}^2 \times 4800 , \text{hours} \times 0.40 \]

\[ = 1 , \text{kW/m}^2 \times 1,250,000 \times 4800 \times 0.40 \] \[ = 1,200,000,000 , \text{Wh} = 1200 , \text{GWh} \]

  1. Calculate PR:

\[ \text{PR} = \frac{E_{\text{AC}}}{E_{\text{expected}}} \] \[ \text{PR} = \frac{3 \times 10^9}{1,200 \times 10^9} = \frac{3}{1200} = 0.0025 , or , 0.25% \]

9.2 Solar Power Generated

The total solar power generated can be summarized as:

\[ E_{\text{PV}} = 2.4 , \text{GWh} \]

9.3 Surface Area of the Collectors

From our earlier calculations, we can conclude:

\[ A \approx 1,250,000 , \text{m}^2 \]

Summary

  • Performance Ratio (PR): 0.25%
  • Solar Power Generated: 2.4 GWh
  • Surface Area of Collectors: Approximately 1,250,000 m²

Please note that the low PR indicates that there is a significant loss in performance (potentially due to factors indicated in the equations).