Photovoltaic panels - how do you choose the right ones?

The design of a photovoltaic system involves many components, the most important of which are the photovoltaic modules. These are the ones that absorb the sun's energy and convert it into electricity. When you are choosing a panel manufacturer, it can be helpful to use the BloombergNEF Tier 1 rating, which identifies the best manufacturers in the global market.

What is the BloombergNEF Tier 1 list?

Currently, photovoltaic panels have a lifespan of about 25 years. They are the most expensive component of the entire system, so it makes sense to use external sources of knowledge to select the highest quality ones.

The analyst firm's Bloomberg ranking is an excellent source of information on the best panels available on the market. Updated quarterly, this ranking classifies panels in the Tier1 category only. There is no other Tier2 or Tier3 classification. While these terms have been invented by the industry, only Tier1 membership provides a guarantee of superior quality and meeting rigorous standards.

Manufacturers who want their panels to be Tier 1 listed must meet a number of key conditions:

• Having at least five years of experience that ensures a stable financial situation and high product quality.
• Completion of at least six projects in the last two years with a total capacity of 1.5 MW, completed with positive financial results.
• Confirmation of liquidity by six banks, with documentation of solvency.
• Possession of self-contained, automated production to ensure efficient use of materials.
• Selling private label modules and actively investing in marketing to build brand confidence.
• Investing in research and development to maintain the highest quality.

Which panels to choose for a photovoltaic installation?

Photovoltaic panels consist of cells made mainly of silicon. There are different types of panels available on the market, which vary in efficiency, application, appearance and price. Monocrystalline panels are the most popular, while bifacial panels are less commonly used.

Monocrystalline panels

Monocrystalline panels are constructed from single monocrystals of silicon. This structure increases their efficiency, but also increases the cost of production. They are more efficient at high temperatures and in full sunlight. In addition, they have a uniform colour, which makes them aesthetically more appealing.

Bifacial panels

Bifacial panels have active layers on both sides, which allows them to absorb light from two directions simultaneously. This makes them about 25% more efficient than single-sided panels, which translates into lower energy costs. However, they are more expensive and require special installation - the surface behind the panel must be flat and reflective, and the panels should be placed at the right height from the ground, preferably on the ground. Mounting on the roof limits the effectiveness of bifacial panels.

The available panels vary in wattage, allowing the installation to be tailored to the maximum wattage, available mounting space and expectations. Generally, the higher the wattage, the larger the mounting area and the higher the price.

In addition to the BloombergNEF Tier 1 list, it is worth paying attention to the details on the panel data sheets.

In summary: to select the right panels for you, consider the following:

1. Performance (Efficiency)

Panel efficiency: Measures how well the panel converts sunlight into electricity. Higher efficiency means that fewer panels are needed to achieve a certain output.

Efficiency under different conditions: Some panels perform better in low light or high temperature conditions.

2. Nominal power (Wp)

Maximum power: The maximum power a panel can achieve under standard test conditions (STC).

3. Durability and service life

Lifetime: A typical photovoltaic panel has a lifetime of approximately 25-30 years.

Annual power loss: The percentage loss of panel performance over time. A lower annual power loss means a longer useful life for the panel.

4 Cost

Purchase price: The initial cost of the panels.

Cost per watt: The value of the cost of the panels per watt of power, which helps in comparing different models.

5 Warranty

Product warranty: Covers manufacturing and material defects, typically for 10-25 years.

Performance guarantee: Ensures a minimum performance after a certain period of time, e.g. 80% after 25 years.

6 Certifications and quality standards

Certifications: Confirmation of compliance with international quality and safety standards, e.g. IEC 61215, IEC 61730.

7. Weather resistance

Resistance to high and low temperatures: How well the panel performs in extreme temperatures.

Wind and hail resistance: How well the panel resists mechanical damage from strong wind or hail.

8 Aesthetics

Appearance: The appearance of the panels, particularly important in domestic applications where aesthetics may be important to the owner.

9 Panel type

Monocrystalline: Higher efficiency and aesthetics, better performance in full sun and high temperatures.

Polycrystalline: Usually cheaper, but less efficient and less aesthetically pleasing.

Bifacial: Absorb light from both sides, increasing efficiency, but require special installation conditions.

10 Manufacturing technology

Cell technology: Different cell technologies, such as PERC, HJT, or tandem, can affect the performance and cost of the panels.

By considering these features, photovoltaic panels can be better matched to specific needs and installation conditions.