What Is the Efficiency of Solar Panels: A Brief Guide



What Is the Efficiency of Solar Panels: A Brief Guide

Solar panel on roof with sun coming up

Many people who switched to a solar energy system for their homes have seen the economic benefits of doing so. Besides having reduced energy costs and gaining financial incentives like tax credits and rebates, existing net metering policies further increase overall savings. 

If you want to go solar but are still on the fence about it, you may be asking, “what is the efficiency of solar panels?” Or, “Do solar panels lose efficiency over time?” Below is a guide to shed light on the matter.

Solar Panel Efficiency: What to Know

Solar panel efficiency is the rate at which solar panel cells convert sunshine into usable electricity. The higher the efficiency rating, the more power a solar panel can produce. That’s why it’s better to opt for a high-efficiency panel—because of its expected output.

The most efficient solar panels have conversion efficiency ratings of about 22 percent, higher than most panels’ standard range of 15 percent. Generally, higher efficiency panels also cost more than their less efficient counterparts due to having superior technology.

6 Factors Affecting Solar Panel Efficiency

Not all solar energy that reaches a photovoltaic or PV cell becomes power; most is lost during the conversion process. Many factors impact solar panels’ efficiency, so manufacturers have these in mind when designing a more efficient one.

1. Solar Cell Material

How efficient a panel is at converting sunlight to electricity depends mostly on its solar cell material. The most commonly used PV materials are monocrystalline silicon, polycrystalline silicon, and cadmium telluride. Among the three, monocrystalline cells have the highest efficiency rating. As they’re made from a single crystal, electrons can move more freely, generating more electricity.

2. Photon Wavelength

Photons are subatomic particles that emit light energy and have a range of visible to invisible wavelengths. When photons strike the surface of a solar cell, they can be reflected, passed through, or absorbed depending on their wavelength. Some of the absorbed photons have enough energy to dislodge electrons from their atomic bonds, resulting in the production of an electric current.

3. Solar Cell Temperature

Solar cells perform better at low temperatures. But when there’s increased heat, their semiconducting capabilities are reduced, generating less power. Moreover, extreme temperature damages components faster. Since most of the incoming sunlight on solar panels becomes heat, thermal management is the key to their efficiency and lifespan.    

4. Cell Reflection

A cell is more efficient if it can absorb as much light as possible. To achieve this, it has to reduce the amount of light bounced off with anti-reflection coatings, textured surfaces, and glass top layers. Moreover, most high-efficiency solar cells come in dark hues like black and navy blue.

5. Climate

The climate can also impact solar panel efficiency. In places where it’s generally sunny year-round like California (which is the nation’s leading producer of solar energy) and Florida, installed solar panels will be more efficient in generating power than in places with snowy, windy winters. 

6. Solar Panel Positioning

A solar panel’s position and angle influence overall efficiency. Placing panels at an optimized angle without anything that may cast a shadow on them can significantly improve their power output.

Solar Efficiency in California, Florida, & Texas

If you live in sunny states like California, Florida, and Texas, you’re likely wondering about solar panel efficiency to determine the cost-worthiness of going solar.

Remember that a panel’s efficiency largely depends on its solar cells. However, the local climate and a solar array’s location—ideally unobstructed and south-facing—will also determine how much sunlight can be captured and turned into usable electricity. 

So for these three states, rest assured that your solar energy system will be efficient under the right conditions.

Do Solar Panels Lose Efficiency Over Time?

Yes, solar panels become less efficient as they age. While durable, their energy production declines due to climate, module type, and racking setup, among other factors. Moreover, physical damage from inclement weather and extreme temperature fluctuations causes them to generate less electricity.

In a National Renewable Energy Laboratory study, solar panel production decreases by 0.5 percent annually. At the end of the average 25-year lifespan, it generates 87.5 percent of its rated output, making it slightly less efficient than a new solar panel.   

Even though panel degradation is inevitable, routine maintenance can slow it down. Have your solar energy system inspected and cleaned periodically by a professional, and pay attention to signs of damage.  

Save More with Solar

Understanding solar panel efficiency is the first step to realizing why going solar is worth the investment in the long run. 

Learn how you can save more with the team from Current Home, a trusted provider of solar services in California, Florida, and Texas. Reach out for an initial consultation or estimate today.