What is Solar Panel Efficiency?

The decision to go solar involves a thorough investigation into what’s on the market, and one question that is often asked is ‘How Efficient are Solar Panels?’. But what does solar panel efficiency actually mean? And how does it affect the decision-making process?

Solar panel efficiency refers to the percentage of sunlight that a solar panel can convert into usable energy. It’s a crucial factor in determining how much power a solar panel system can generate from a given area. The more efficient a solar panel is, the more energy output it will have per cell, which will take up less surface area to meet your energy requirements.

Solar panel efficiency refers to the percentage of sunlight a solar panel can convert into usable energy. Solar panels with a higher efficiency can generate more energy from the same sunlight.

How To Calculate Solar Panel Efficiency

Many manufacturers will quote the assumed efficiency, but for a more personalised result, use this efficiency formula for solar panels.

Efficiency % = Power Output (W)
                       Solar Energy Input (W/m2) x Panel Area (m2)

1. Check the manufacturer information for the power output in watts.
2. Measure the panel area (length x width)
3. Determine the solar irradiance (1,000 W/m2 under standard conditions)

What Affects Solar Panel Efficiency?

The efficiency of a solar panel is affected by a variety of environmental, physical and technical factors. Let’s take a look.

• Sunlight Intensity (Solar Irradiance)
  • The more sunlight reaches your panels, the more power they can produce. The weather, seasonal changes and location all have a direct impact on the solar panels ability to convert sunlight into electricity.
• Temperature
  • Surprisingly, hot weather does not always increase efficiency. High temperatures increase electrical resistance in solar cells, lowering efficiency slightly. 25°C is the optimal temperature for most solar panels.
• Shade
  • Shading from trees, buildings, and other obstructions can dramatically reduce solar cell performance. A solar panel installation is often comprised of a series of connected panels; if one panel is shaded, this can impact the whole series.
• Dirt and Debris
  • The buildup of dust, dirt and other debris prevents sunlight from reaching the solar cells.
• Panel Position
  • Panels facing true south offer the maximum potential to capture sunlight. Panels that can be tilted and moved either manually or mechanically can be altered to an optimal position.
• Panel Age
  • Solar panels naturally degrade over time. Experts suggest a 0.5% to 1.0% reduction in efficiency every year. This is due to environmental wear and material breakdown.
• Equipment Quality
  • High-quality panels and inverters offer better conversion rates and maintain their performance over time.

Some of these factors are within the control of solar panel owners. Maintaining your solar panel installation and keeping it free from obstructions can significantly improve output and lifespan.

How Inverter Efficiency Impacts Your Solar System

Generating the maximum efficiency from your solar panel installation is crucial because it directly impacts how much energy is produced. This is important as the more solar electricity you have, the less you have to purchase from the grid. Or if you make more energy than you need, the more you can sell back to the grid.

While there are several efficiency factors regarding solar panels, the inverter also plays a crucial role in how much usable energy a system produces. An inverter is an essential component of a solar system.

An inverter converts the direct current (DC) electricity generated from solar panels into alternating current (AC) electricity. Without an inverter, the electricity generated from solar panels wouldn’t be compatible with your home’s wiring.

During the conversion process, some electricity is lost. A high-quality inverter will only lose 1-5% of the energy generated.

Most Efficient Solar Panels

Monocrystalline solar panels are generally considered the most efficient type of solar panel available. They are a type of photovoltaic panel made from a single, continuous crystal structure of silicon. Unlike polycrystalline panels that are made from multiple silicon fragments, monocrystalline panels are created using a single, pure silicon crystal.

It is this structure that makes them more efficient by allowing electrons to move freely, leading to a higher conversion rate of sunlight into electricity.

Monocrystalline panels are usually more expensive as they are complex to produce. But they are exceptionally durable and known for their long lifespan. Their sleek, black exterior, high conversion rate and lifespan make them a popular choice among homeowners and businesses.

With the current focus on renewable energy, investing in solar research is big business. Solar technology is constantly evolving, and efficiency looks set to improve as new developments become more mainstream. Perovskite solar cells, bi-facial panels and thin-film solar cells all offer considerable improvements in solar panel efficiency.