Evaluating and Comparing Solar Quotations for your hotel

As a Chief Engineer, your role in evaluating solar quotations is crucial for ensuring that your hotel makes a well-informed and cost-effective investment. Solar energy is an excellent way to reduce operational costs and enhance sustainability, but selecting the right system requires a thorough comparison of multiple proposals. In this article, I will guide you through the key aspects to consider when evaluating solar quotations and how to perform an apple-to-apple comparison to make the best decision for your hotel.

1. Prices and Main Details

Start by reviewing the total costs presented in the quotations. It's essential to break down the costs based on different scenarios to get a clear picture:

• Total Cost with Cu Underground Armoured Cables: This cost includes copper cables provided by the hotel. Copper offers better conductivity and is particularly advantageous in marine environments where corrosion resistance is critical. If your hotel is located near the coast, this option may provide better long-term durability compared to aluminum cables.
• Total Cost with Al Underground Armoured Cables: Aluminum cables, also provided by the hotel, are less expensive than copper but may affect efficiency and durability, especially in harsh environments.
• Total Cost with Al ABC (Overhead) Cables: Aluminum aerial bundled cables (ABC) include the cost of laying them, often handled by the supplier. While this may be a more cost-effective solution, it is generally less suitable for marine environments due to potential corrosion.

In addition to the costs, you should also compare the cost per kilowatt (kW) for Solar PV, the proposed AC capacity (in kW), and the DC capacity (in kWp). A critical metric to analyze is the average generation per month during the first year (in kWh). Finally, calculate the Return on Investment (ROI) and the equity payback period to assess the financial viability of each proposal.

2. Solar PV Panel Specifications

Next, delve into the technical specifications of the solar panels:

• Type of Solar PV Panel (P-type or N-type): P-type (Positive-type) panels are the most common and typically use boron as the dopant in the silicon cells. They are more affordable but tend to degrade faster due to light-induced degradation (LID). N-type (Negative-type) panels, on the other hand, use phosphorus as the dopant and are less prone to LID, offering better performance over time, especially in high-temperature environments.
• Monocrystalline vs. Polycrystalline: Monocrystalline panels are made from a single crystal structure, offering higher efficiency and better performance in low-light conditions. Polycrystalline panels are made from multiple silicon crystals and are usually less expensive but slightly less efficient.
• PERC Module or Not: PERC (Passivated Emitter and Rear Contact) technology adds a layer to the rear of the solar cells, reflecting unabsorbed sunlight back into the cell, increasing energy capture. This technology enhances the overall efficiency of the panels, making them more productive, especially in high-temperature environments.

Other crucial factors include the panel's wattage value, dimensions (LWH), number of panels proposed, and the manufacturer’s brand and warranty. The warranty period is essential to consider: many manufacturers offer warranties ranging from 10 to 25 years for performance and product quality. The panel efficiency (including degradation over time) should be carefully considered to ensure long-term performance.

3. Inverter Specifications

Inverters are a vital component of your solar system. Compare the following:

• Inverter Capacity: Ensure the capacity matches your hotel's energy needs.
• Type of Inverter: Whether it's a string, central, or micro-inverter, each has its pros and cons depending on your hotel's layout and shading conditions.
• Maximum Power Point Tracker (MPPT): Inverters with MPPT can optimize the power output from the solar panels, which is particularly useful in variable weather conditions.

Look at the manufacturer's brand, country of origin (COO), and warranty scope to compare the reliability and durability of the inverters. The warranty period typically ranges from 5 to 10 years, depending on the manufacturer. Also, consider the number of inverters proposed and their maximum efficiency.

4. AC and DC Specifications

Examine the AC and DC specifications provided in the quotations:

• AC Cables: Compare the specifications for aluminum and copper armoured cables, particularly in terms of durability in a marine environment.
• DC Cables: Pay attention to the product and country of origin, as well as the material used in the cables, as these factors affect both cost and performance. The warranty period for cables can vary, so ensure you consider this in your comparison.
• AC DB Boards and Switchgears: These components are critical for the safe distribution of electricity. Ensure they meet industry standards and come with an appropriate warranty.

5. Solar PV Earthing System Specifications

The earthing system is a crucial safety component:

• AC and DC Surge Diverters: Check the brand and COO of surge diverters for both AC and DC sides. These protect your system from electrical surges.
• Warranty for SP Equipment: Ensure there is a warranty for the surge protection equipment, as this adds another layer of reliability to your system.

6. Other Considerations

Lastly, consider additional costs and similar projects:

• CEB/LECO Clearance Fee and Connection Fee: These are often overlooked but can add to the total cost.
• Similar Projects in Hotels: Reviewing similar projects can provide valuable insights into the performance and reliability of different systems. Don’t forget to check the warranty period for the entire system, as this can vary depending on the project specifics.

Conclusion

By methodically comparing solar quotations using the above criteria, you can ensure that your hotel selects the most cost-effective and efficient solar system. Remember, a detailed apple-to-apple comparison not only helps in making an informed decision but also ensures that the selected solution aligns with your hotel's sustainability goals and operational needs, especially in challenging environments like those near the coast.