Solar power plants are the need of the day; they are an effective solution for the growing energy demands. For their efficient working processes, preventive maintenance is the key element. High-tension (HT) feeders support the electrical infrastructure of a solar power plant. These feeders deliver solar-generated power to the grid or distribution network. The proper functioning of these vital components ultimately affects the whole plant’s dependability and efficiency. 

What is an HT Feeder?

In the case of a solar power plant, a high-voltage electrical system or wire is also referred to as an HT feeder, sometimes known as a High-Tension Feeder. Its purpose is to transmit solar energy, which normally operates at a low voltage, to a greater voltage level that may be incorporated into the wider electrical grid. To provide safe and efficient power transmission, HT feeders are outfitted with various parts, including transformers, circuit breakers, and safety equipment.

The main role of HT feeders in solar power plants is to transmit electricity at higher voltages; they help in voltage transformation, grid integration, efficiency, and safety.

Main components of HT panel:

  1. Circuit breaker.
  2. Relays
  3. Meters
  4. CT and PT

Importance of HT Feeders:

Regular maintenance of HT feeders has a lasting impact on solar power plants; it contributes significantly to system reliability, thus reducing failure rates. We can understand it from the below curve.

The graph shows that the failure rate is highest at the beginning of a component’s life. It decreases during the operational phase and then increases again as the component reaches the end of its lifespan. Regular maintenance effectively reduces the initial and wear-out failures.

We can use Mean Time Between Failures (MTBF), a reliability matrix that quantifies the average time between the equipment failures. A higher MTBF value indicates greater reliability.

MTBF=Total operating time/number of failures

Impact on System Performance:

Maintenance also has a good impact on systems performance. It can help in;

Energy Yield Optimization:

Due to dust, dirt, shading, and wear, solar panel performance can deteriorate over time. Regular cleaning can reduce energy losses and maximize energy yield. 

Reducing voltage drop:

The voltage drop can be calculated using Ohm law.

vd=I * R

Regular maintenance ensures that connections are tight (reducing resistance), thus minimizing voltage drop and increasing the efficiency of solar power plants.

The HT Feeders Pre-Maintenance Checklist:

Preventive Maintenance Checks:

1). First, confirm the issuance of a work permit before starting any kind of maintenance activity

2). Ensure that the concerned power breaker is racked out to an isolated position 

3). Discharge the power terminals safely.

Inspection and Testing:

  1. Cleaning HT panels with an air blower 
  2. Checking indications for 33kv HT panel.
  3. Ensure that the panel covers are securely closed.
  4. Testing of vacuum circuit breaker (VCB) from local and remote modes via SCADA.
  5. Checking or replacing damaged or missing “Danger” signs.
  6. Verify the proper functioning of energy meters, ammeter, and voltmeter.
  7. Ensuring all cable terminations are tight.

Final Checks:

  1. First, check the spring charging motor of the HT panels and ensure it is in working condition.
  2. Verify breaker test and service position. 
  3. Check any loose connections by inspecting the wiring.
  4. Check bus PT and line PT connections of the 33kv HT panel.

Frequency of HT Feeder PM:

The frequency of preventive maintenance for HT feeders in a solar plant depends upon several factors, some of which are defined below.

  1.  Manufacturer recommendations 
  2. Environmental conditions 
  3. Operational cost.
  4. Historical data.
  5. Regulatory requirements.
  6. Risk assessment.

Cost minimization:

Total maintenance cost: This includes the total cost of maintenance.

TMC = Labor Cost + Materials Cost + Equipment Cost + Overhead Cost

Return on investment (ROI) from preventive maintenance measures the financial benefit gained from PM compared to its cost.

ROI= [Savings from Preventive Maintenance – Cost of Preventive Maintenance Cost of Preventive Maintenance /]x 100%


Effective maintenance of HT feeders in solar power plants is critical for ensuring the entire system’s reliability, safety, and efficiency. This blog has also highlighted the economic advantages of preventive maintenance and cost-minimization formulas to be incorporated for economic results.

Click below to download the sample file for HT Feeder Preventive Maintenance – 

Download Sample FileHT Feeder P.M Checklist Sample


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