3.2.1. Impact on the Primary Substation

The primary substation (equipped with 2 × 5 MVA, 38/10.47 kV transformers giving a total continuous supply capacity of 10 MVA). Power flow analysis results using feeder circuit demand for winter peak load reading indicated total demand excluding the project was 7.19 MVA, including the project was 7.58 MVA and including the project with solar PV systems was 7.58 MVA. Summer minimum load reading indicated the total demand excluding the project was 4.93 MVA, including the project was 5 MVA and including the project with solar PV systems was 4.93 MVA [32].

### 3.2.2. Impact on the MV Feeder Circuit

The 10.47 kV feeder circuits consisted of a mixture of underground cables and overhead lines. Each feeder circuit was controlled by a circuit breaker which was installed in a primary substation rated at a capacity at 630 Amps (11.4 MVA). Each feeder circuit left the substation as an underground cable with a rated winter current of 532 Amps (9.65 MVA), the MV feeder circuits (underground cable and overhead lines) conductor size drastically reduced as demand decreased. Results of the power flow analysis demand for the winter peak load reading indicated total demand from all the feeders connected to the primary substation excluding the project was 2.34 MVA, including the project was 2.71 MVA and including the solar PV was 2.71 MVA [32]. Summer minimum load reading indicates total demand excluding the project was 1.91 MVA including the project was 1.98 MVA and including the project with solar PV systems was 1.91 MVA [32].

### 3.2.3. Impact on the Distribution Transformer and LV Network

The distribution transformer supplied the LV network and had a continuous rating of 630 kVA. Power flow analysis using electricity demand profiles for the winter peak load reading indicated [32]: the total demand on the distribution transformer including the project was 374 kVA; including the project with solar PV systems was 374 kVA. Summer minimum load demand including the project was 68 kVA and including the project with solar PV systems was 121 kVA.

The LV network was equipped 185 mm<sup>2</sup> cross sectional area conductor underground cable which consisted of six feeders to supply the project. The power flow analysis [32] using electricity demand profiles for the winter peak load reading giving total demand on LV feeders with and without solar PV system is shown in Table 3. The summer minimum load reading demand on LV feeders with solar PV is assumed, in this study, to be same as Table 3 above which is the worst-case scenario summer loading of LV feeders.


**Table 3.** Total demand on LV feeders with and without solar PV system [32].

### 3.2.4. Impact on the Network Losses

The technical losses occur because of the energy dissipated in feeder circuit conductors and core and windings losses in transformers [32]. Winter peak load reading indicated total technical losses in the existing electrical network excluding the project was 85 kW, including the project was 106 kW and including the project with solar PV systems was 106 kW. For summer minimum load reading the total technical losses excluding the project was 61 kW, including the project was 64 kW and including the project with solar PV systems was 62 kW [32].

## 3.2.5. Impact on the Voltage Profile

Voltage is the electric potential difference between two points. The voltage drop is the reduction in voltage in an electrical circuit between the source and load [47]. The voltage drop on feeders occurs because of: resistance increase from poor joints and terminations, hot spots, under-sized conductors and non-uniform conductor material or load increases [48]. Results of the power flow analysis carried out by [32] at MV feeder and LV feeder circuits indicated voltage at the MV feeder circuits including the project ranged from a maximum of 100% at primary substation to a minimum of 98.1% 16 km away. The voltage at the distribution substation including the project ranged from a maximum of 97.8% to a minimum of 96.2% at distribution substation. The voltage at the LV network entry point to a point 170 m closer to the project declined by another 2% [32].
