Energy efficiency is an important factor to consider as you shop for home solar panels, but what does energy efficiency mean? We’re here to help you make sense of solar panel efficiency, and we’ll help you maximize it so you can get the most out of your home solar system. 

Want an industry-leading solar system for as little as $0 down? Schedule a solar consultation with one of our expert Solar Advisors today.  

How efficient are solar panels?

To determine solar panel efficiency, sometimes referred to as photovoltaic conversion efficiency, we measure how much energy from sunlight is transformed into electricity.¹ The average commercial solar panel converts 17-20% of sunlight into electricity.² While 20% might not sound like a lot, it’s enough to keep the average American home powered throughout the day. 

Even the best semiconductors only capture a fraction of the light that strikes them.³ Much of the light that strikes solar panels is reflected back, passes through the panel, or is converted into heat instead of electricity.³ That’s why the residential solar panels you often see appear dark blue or black.⁴ These “anti-reflection” coatings ensure the solar panels absorb as much sunlight as possible to maximize efficiency.⁴

What are the different types of efficient solar panels?

When it comes to choosing the most efficient solar panels for your residence or establishment, there are two solar cell types that come to mind: polycrystalline and monocrystalline solar panels. Let’s discuss each type in more detail.

The primary distinction between monocrystalline and polycrystalline solar panels lies in the composition and structure of their solar cells, which directly impact their energy output and energy usage.

Monocrystalline Solar Panels

Monocrystalline panels utilize solar cells made from a single crystal structure. These cells are crafted using a continuous crystal lattice of high-purity silicon. As a result, monocrystalline panels exhibit a uniform and sleek appearance, often in black or dark blue. They tend to achieve higher efficiency rates, converting a greater percentage of sunlight into electricity. This enhanced efficiency translates to higher energy production, making them suitable for situations where space is limited or maximizing power production is crucial.

Polycrystalline Solar Panels

In contrast, polycrystalline panels consist of solar cells composed of multiple silicon crystals. The manufacturing process involves melting raw silicon and forming square-shaped molds to create ingots. This approach yields a less uniform appearance with a speckled, blue-colored surface. Polycrystalline panels exhibit slightly lower efficiency rates compared to their monocrystalline counterparts. But recent technological advancements have narrowed this efficiency gap over the years.

Thin Film Solar Panels 

Thin film solar panels, also known as thin film photovoltaic (PV) modules, are a lightweight and flexible alternative to traditional crystalline silicon panels. Unlike rigid PV cells, thin film panels are made by depositing a thin semiconductor material layer onto a substrate. This technology allows for unique applications and integration into curved surfaces, making them ideal for building-integrated photovoltaics (BIPV) and portable solar chargers. 

However, thin film solar panels generally have lower efficiency rates compared to crystalline silicon panels. Despite this, they offer advantages such as better performance in low light conditions and higher temperature tolerance. Ongoing advancements in thin film solar cells continue to improve the efficiency and performance of these renewable energy solutions.

Do solar panels degrade over time?

As with most technologies, PV cells will naturally produce less energy over time. This reduced power output is called the degradation rate. The median solar panel degradation rate is about 0.5%, which simply means that a solar panel’s energy production will decrease at a rate of 0.5% per year.⁵ After 20 years, your panels should still be working at about 90% of their original output. 

While solar systems typically last upwards of 20 years, repairing and replacing a solar energy system can come at a high cost.⁶ When you lease a solar system with Sunrun, all you have to do is pay for the solar power—we’ll take care of the rest. Our solar lease includes free system monitoring, maintenance, and repairs so you can enjoy 25 years of worry-free, clean energy.

How does weather affect solar panel efficiency?

Even in below-freezing weather, solar panels turn sunlight into electricity. That’s because solar panels absorb energy from our sun’s abundant light and not from the sun’s heat. In fact, cold climates are actually optimal for solar panel efficiency.⁷ As long as sunlight is hitting a solar panel, it will generate electricity. Less output during the winter months will primarily be due to shorter daylight hours or possibly heavy snow.

This doesn’t mean that solar panel output will decrease in warmer weather; any diminished efficiency is balanced out thanks to more daylight hours during the spring and summer months.⁷

Do solar panels work in rain and snow?

If your winters look cloudy, rainy, snowy, or all of the above, not to worry. Solar panels can still generate electricity under these conditions, too. While solar panels are most productive in direct sunlight, they can still use diffuse or indirect sunlight (radiation) to generate energy.

Even though energy production decreases with increasingly dense cloud cover, panels continue working to a greater capacity than one may expect. Rain also helps wash away dust on panels to keep them operating efficiently.

During times of heavy snow accumulation, solar panels’ dark, reflective glass accelerates snow melt so that it slides off before it can hamper performance. Rooftop solar panels are also typically tilted up at 30 to 45 degrees, which keeps snow from accumulating, but only to a point.¹¹ In comparison, a light dusting of snow is likely to blow off or disappear rapidly. 

In fact, on cold, clear days, snow from the ground can reflect extra sunlight onto your solar panels like a mirror. This “albedo effect” enables panels to produce even more electricity in the cold.¹⁰

If your panels require more than a routine hosing down or require you to get on the roof, we highly urge you to contact a trusted solar provider to receive professional assistance.

Three tips on maintaining solar panel efficiency

While solar panels generally require little maintenance, it’s still important to inspect your solar panels from time to time and monitor their performance. Here are a few tips to ensure your solar installation is working at its full capacity:¹²

Keep solar panels clear of debris

While rain is generally sufficient to keep your panels clean, you may want to consider a professional cleaning if you ever notice your panels aren’t working at their full capacity.

Ensure solar panels are monitored and maintained

If your solar panels underperform after rainfall or are being hosed down with water, or if you see an unusual spike in your utility bill, it may point to an electrical problem that needs to be addressed by a professional.

Team up with a trustworthy solar company

The best thing you can do to ensure your solar system’s longevity is to find a reputable solar installer. Although solar systems require little regular maintenance, some solar providers offer comprehensive maintenance packages for the life of their products to ensure they maintain their solar cell efficiency and generate clean, affordable, and reliable energy for decades.

Sunrun has over 14 years of solar panel installation experience and partners with only the most highly-trained solar installers in your neighborhood to provide you with worry-free solar power. 

Energy efficiency vs. Cost efficiency

While solar panel efficiency is important to consider, cost efficiency will likely be the most relevant factor in your search for the most efficient solar panels. Sunrun ensures you have a cost-efficient system in three ways:

We only recommend a solar panel system if it has the potential to save you money.

Sunrun will help you determine whether a solar panel system has the potential to cut the cost of your current electricity rates. Our easy-to-use Product Selector will ask you for your average monthly electricity bill so our Solar Advisors can determine if solar makes financial sense for you.

Lock in predictable rates for as little as $0 down. 

Sunrun’s monthly solar plan, also known as a solar lease, allows you to go solar for little to nothing out of pocket. You’ll lock in a low rate for 25 years, which offers additional peace of mind as utility bills continue to rise.¹³ We even provide you with the option to prepay the lease in full with just one up-front payment. 

Our solar lease is also backed by our industry-leading Solar Guarantee, which includes 24/7 monitoring and maintenance, as well as full insurance coverage. When you choose a solar lease, you’ll have control over your energy bills. We take care of the rest.

Offset peak electricity rates with a solar battery.

High-efficiency solar panels paired with battery storage can help buffer you from peak electric rates. For states with Time-of-Use or TOU rates, investing in solar power with a home battery allows you to run your appliances when you want and not when electric companies tell you to. Excess energy is stored in your home battery, and you can use it when you need it the most while further optimizing your energy savings.

Renewable energy and efficient solar panels for your energy needs

A reputable residential solar company will guarantee higher efficiency panels, reliable solar panel production, and dependable customer service for decades to come. With over 20 years of experience, Sunrun is committed to creating a sustainable energy future for all.

See why over 600,000 Americans across the country have partnered with Sunrun. Get a solar consultation today. You can also use our easy Product Selector to get a solar system that’s custom-fit to meet your needs.