Solar Panel Energy Efficiency and Degradation Over Time

Panel efficiency and longevity stand as critical factors shaping sustainability in the solar industry. Understanding the balance between harnessing sunlight for optimal energy conversion and the unavoidable degradation is essential. Today let us find solar panel efficiency and why it degrades over time.

Solar Panel Energy Efficiency and Degradation Over Time

The process of converting sunlight into electric energy with respect to the ability of solar photovoltaics is called solar panel energy efficiency. It is determined by the amount of energy produced per unit of surface area. A higher energy output from a specific surface area indicates greater efficiency, while a lower energy output implies lower efficiency projection.

However, after some time, solar panels degrade in their efficiency which decreases their life span gradually.

The National Renewable Energy Laboratory mentions that the degradation rate is around 0.5% to 0.8 % per year but varies depending on the model, brands, and types of panels.

Factors Affecting Degradation of PV Modules of Solar Panel

1. Degradation Due to Light Induction: This occurrence affects solar panels, in which efficiency is reduced temporarily at the primary exposure of sunlight. This is due to the motion of boron and oxygen within the silicon cells.

2. Degradation due to Potential Induction: The process by which PV in the solar panels originated by the flow of current between cells and other components causes the loss of performance.

3. Aging-related Degradation: PV modules after years of operation lose their performance due to environmental factors and thermal stress.

4. Backsheet Failure: For a PV module, the back sheet acts as a rear protective layer and is made up of polyvinyl fluoride polymer material.When this has a discoloration, the formation of bubbles of delamination would lead to degradation.

Also See: 10 Ways to Protect Solar Panels from Hail

Solar Panel Efficiency Calculator

The following formula is used to calculate the efficiency 

Solar Efficiency in Percentage(%) = ((Maximum Power /Area)/(1000)) * 100%

• Maximum Power is the highest amount of energy output of the panel, written in watts (W).
• Area means the surface area of the solar panel, which is written in square meters (sq.m.).

For example, the maximum power of a panel is 200W and has an area of 1 sq. m.

So, using the solar panel energy efficiency formula, we have,

Efficiency (%)  = ((200/1)/1000)*100% = 20%

Maximum Efficiency of Solar Cell

Energy’s National Renewable Energy Laboratory (NREL) mentions in their studies that the highest efficiency rate is 39.5%  for a triple junction solar cell.

However, the highest recorded efficiency for solar cells is 47.1%, for multi-junction concentrator solar cells.

Note: This remarkable record was established under laboratory conditions using highly concentrated light.

Why Solar Panel Efficiency is Low?

Here are some common reasons responsible for low solar panel efficiency projections:

1. Location impacts: When solar panels are placed in regions with lower sunlight or frequently clouded areas, the light will affect efficiency.

2. Manufacturing defects: When purchasing, invest in high panels for long-term durability; poorly manufactured panels are vulnerable to degradation over time.

3. Inverter issues: The inverter also impacts its functions, and can cause lesser output.

4. Maintenance:  As panels are kept on an open surface dust, bird droppings or debris accumulates which results in the blocking of sunlight. Cleaning panels very often is essential to ensure peak performance.

5. Technical wastage: Power losses in the wiring, connections, and electrical components of the solar power system can contribute to reduced efficiency.

6. Angle of setup: This is important for panel system setup. Not maintaining an optimal angle or misplaced orientation will reduce the chances of facing sunlight, which reduces efficiency.

You can also check out the Ways to Increase the Panel Efficiency.

Solar Panel Degradation Curve

The below graph shows the degradation of solar panel’s efficiency over time which helps us to understand their long-term performance.

Cost of Solar Panels Over Time Graph

Since its emergence, the cost of solar panels has experienced a downtrend, making it a cost-effective natural energy source for mankind

The following general trends describe the changes in panel costs over time.

1. Opening Costs (1975 – 1990): In the initial days solar panel technology was new and expensive. The production itself costs more and it took time to reach efficiency.

2. Swift Fall of Costs (1990-2000): As technology improved, manufacturing also improved and government incentives also went hand in hand. There is a gradual decrease in costs in this period.

3. Declining costs further (2000-2010): As demand grew, competition increased among manufacturers, so they became abundant leading to the price drop.

4. Increased Affordability (2010s-2020s): Grid parity, where the cost of solar electricity equals or becomes cheaper than conventional grid electricity; makes it affordable to both residential and commercial projects.

This is the graph, where you can visualize these trends of costs over the years.

Cross-reference: Solar Manufacturing Cost Analysis

Do Solar Panel Warranties Account for Efficiency Loss?

Yes, manufacturers give warranties that facilitate panels to retain at least 97.5% efficiency after one year and 85% approximately after 25 years. However, the efficiency drop is different for every solar brand.

To sum up, the gradual decline in efficiency or degradation impacts the long-term performance of solar panels. It depends on the manufacturing processes; however, industry standards often include degradation warranties that specify the expected loss of efficiency over a certain number of years. To access more such informative content, keep reading our blog posts.

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