Are solar panels efficient?

Key takeaways

• Average solar panel efficiency ranges from 10% to 20%, but can reach 24% in some cases.

• Monocrystalline silicon panels are the most efficient solar panels on the consumer market.

• Other parts of a solar energy setup can also impact the system-level efficiency.

Modern solar panel technology is far more efficient than it used to be. However, the efficiency of your solar panels and the system at large can vary quite a bit based on the equipment you use and how it is installed and maintained.

In this article, we discuss which types of solar panels are the most efficient and the other factors that contribute to the efficiency of your energy system. You’ll also find a brief guide to maximizing your solar energy efficiency.

How efficient are solar panels?

Solar panels convert sunlight into electricity, but their efficiency depends on technology, solar panel types, weather, and installation. Most commercial solar panels achieve conversion efficiencies between 10% and 24%, meaning they convert that percentage of solar energy into usable electricity. Monocrystalline panels, known for their high performance, often top the range, while polycrystalline and thin-film panels typically produce less.

Factors like temperature, shading, and orientation can further impact output. Advances in photovoltaic cell materials, like silicon and perovskite, continue to push efficiency higher. Though no solar panel captures all sunlight, modern solar technology reliably reduces reliance on fossil fuels and lowers carbon emissions.

Most efficient solar panels by type

The efficiency of a solar panel depends on its type, with monocrystalline panels currently offering the highest efficiency rates among commercial options. Monocrystalline panels convert sunlight to electricity more effectively than polycrystalline and thin-film alternatives.

Most efficient solar panels: Monocrystalline silicon

Monocrystalline panels are the highest-efficiency type of solar panel widely used for residential systems. They are made from a single silicon crystal structure. This enables them to capture and convert more sunlight into usable energy and gives them superior longevity compared to other types.

This high-efficiency design does, however, come at an additional cost. Monocrystalline silicon panels are also more expensive than other types. Even so, their energy-generating capacity and durability have made them the most popular type of solar panel design in the country.

More efficient solar panels: Polycrystalline silicon

Made by melting multiple silicon crystals into a single unit, polycrystalline solar panels are less efficient than their monocrystalline counterparts. However, they are still very efficient compared to many other options. 

Polycrystalline panels are also less expensive than monocrystalline panels. This makes them a middle-ground choice for homeowners, providing moderate efficiency at a moderate price. Homes with larger roofs can use more panels to make up for the per-panel efficiency difference between polycrystalline and monocrystalline panels.

Less efficient solar panels: Thin-Film (CdTe, CIGS, a-Si)

Thin-film solar panels are less efficient than both monocrystalline and polycrystalline panels. However, their lightweight and flexible construction makes them a viable option in places where other panels may not work, such as curved roofs or other nontraditional surfaces. 

They are also a strong option for portable solar energy systems or setups mounted to RVs and camper vans. CdTe uses cadmium telluride, CIGS combines copper, indium, gallium, and selenide, while a-Si uses non-crystalline silicon.

Another big advantage of thin-film panels is price. These panels are considerably less expensive than monocrystalline and polycrystalline solar panels. That makes them a good choice for people with a smaller budget to work with or those who only want to supplement the energy they get from the grid, rather than use solar for all their energy needs.

Factors that affect average solar panel efficiency

Solar panel efficiency depends on several key factors, each influencing how much sunlight your system can convert into usable energy.

• Location: If you live in sunnier regions, your panels get more sunlight, increasing overall efficiency.

• Angle: Mounting panels at the right tilt ensures they capture the most sunlight throughout the day.

• Surrounding environment: Shade from trees or buildings can block sunlight, reducing your system’s effectiveness.

• Temperature: High temperatures can actually decrease panel performance, while mild climates help maintain efficiency.

• Dirt: Dust and grime on panels block sunlight, so you’ll need to keep the surface clean for optimal output.

• Age: Solar panels lose about 0.5% efficiency each year, so expect some decline as your system gets older.

System-level performance vs solar panel efficiency

When you're evaluating your solar power system, it's important to consider the efficiency of the entire setup—not just the solar panels themselves. Other critical components, such as your inverter, wiring, and solar battery, also have their own efficiency ratings that can impact how much usable electricity you get from sunlight. When you combine the performance of all these parts, you're looking at what's called system-level efficiency.

Inverter efficiency

Solar energy systems use inverters to transform the DC energy created by the PV cells into AC electricity that you can use in your home. Some of the energy generated by your panels is lost in this process. The standard range for energy efficiency in the DC to AC conversion is between 95% to 98%.

Wiring and connector losses

System-level efficiency can also degrade due to issues with the wiring and connections that carry electricity from one part of the system to another, or from the system to your home. Frayed wiring, loose connections, or inferior conducting materials used in wiring can cause a loss of efficiency across your system. This is why it’s a good idea to occasionally inspect wiring and connection points—especially if your system isn’t running as efficiently as it should.

Battery storage inefficiency

If you have a solar battery attached to your system, this can also be a source of efficiency loss. Lithium-ion batteries can gradually lose stored energy over time, especially as they get older. Also, connection points and wiring to and from the battery can be a point of efficiency reduction.

How to increase solar panel efficiency through better system design

Optimizing your solar panel system's design can boost its efficiency by improving energy capture, reducing losses, and aligning components like inverters, wiring, and panel orientation. Here are a few things to consider.

1. Buy high-efficiency solar panels

The first step to an efficient solar energy system is the panels themselves. How effectively your solar panels convert sunlight into electricity will set the ceiling for how efficient your system is as a whole. Some properties may be ideal for bifacial solar panels, which can capture light that reflects off of mounting surfaces in addition to light from above.

Spending a little more to get more efficient solar panels will likely end up providing greater energy savings, which could make them the cheaper option over the lifetime of your system.

2. Optimize your installation

Where your solar panels are installed on your home and the angles at which they are installed can make a big difference in their efficiency. These are all things that can easily be measured and analyzed with a little extra time and the proper knowledge and equipment. Make sure your solar contractor takes the time to figure out the optimal configuration for your panels.

3. Reduce or eliminate shade

If tall trees surrounding your home cast shade on your roof, you won’t be able to get the full potential out of your solar panels. Consider removing branches or even entire trees to prevent them from blocking out sunlight. Alternatively, you may be able to mount your panels in a position that is less affected by shade.

4. Keep your panels clean

Dirt and dust building up on the surface of your solar panels is a certainty. How quickly that happens depends on the environment where your home is located. During the first year that your solar panels are installed, check to see how fast grit and grime accumulate so you know how regularly you’ll need to clean your panels. Check on your panels following big storms or heavy winds that can cast dust and debris on them.

5. Invest in an efficient inverter

A difference of 3% efficiency between a higher-quality inverter and a cheaper one may not sound like much, but over the life of your system, that can add up to make a substantial difference in energy savings. Just like with the panels themselves, whatever you save by going with a less efficient inverter will likely be negated by a reduction in energy savings.

6. Monitor system performance

Another key to maintaining the efficiency of your solar energy system is knowing how efficient it is. You can use apps or analyze your electricity bill to figure this out. Then, you’ll know when you’re experiencing a loss in efficiency and need to find out why.

Bottom line: maximizing solar panel efficiency

Maximizing the efficiency of your solar panels directly impacts your long-term energy savings and sustainability. If you invest in premium photovoltaic cells, keep them clean, and optimize their angle, you’ll significantly boost your system’s output and reduce your electricity costs over time.

That said, solar isn’t best for everyone. Take the time to make sure your home is conducive to efficient solar panels.

FAQ about solar panel efficiency

Below are a few frequently asked questions about solar panel efficiency:

Will solar panels ever reach 50% efficiency?

Solar panels could theoretically reach 50% efficiency someday. However, the current record for solar efficiency is 47.6%, set in 2022.

What does 20% efficiency mean for solar panels?

The figure of 20% efficiency for solar panels means that the panels convert 20% of the sunlight they capture into DC energy. This is at the upper end of the normal range for solar panel efficiency.

What is the best efficiency of solar panels?

The best efficiency of widely available solar panels is about 24% for monocrystalline silicon panels. Average efficiency for solar panels ranges from 15% to 24%.

How efficient are 10-year-old solar panels?

At 10 years old, most solar panels should run at about 95% of their original efficiency rating. Most solar panels lose about 0.25% to 0.55% efficiency each year of operation.