does solar efficiency change over time

How Does Solar Panel Efficiency Change​?

How does solar panel efficiency change over time? In this guide, let's break down it all down based on cost and factors such as maintenance and physical properties.

Moore’s law states that every eighteen months processing abilities will double while costs will be slashed in half. Interestingly enough, a similar progression is happening in the solar industry.

Solar efficiency rates are climbing the charts at increasing speeds and costs are simultaneously falling, even for the consumer.

Read on to learn everything you need to know below:

Solar Panel Efficiency - Quick Snap Shot

The first solar cell was created in the 1800s but these cells could only produce as far as an 1% efficiency that isn't practically useful until the rapid advancement in the 1960s.

Fast forward to the 1960s, the efficiency has risen past 14%, and now in the range of 15-17% for serious green energy implementation for regular households, and has become ever more popular.

Most consumers factor in efficiency to be the most important spec while trying to balance between cost.

The more efficient the more the panel can product electricity than less efficient panel, and that's determined by the quality of the solar cells.

  • Cell composition
  • Electrical configuration
  • Surrounding component

Companies like SunPower, Panasonic, and SolarCity all came out with panels with ratings of about 22% efficiency. The last viable jump was in 2016 when the National Renewable Energy Laboratory and the Swiss Center for Electronics and Microtechnology achieved 29% efficiency. 

Check out these panels here if you're interested

Cost Are Dropping

Even as solar panels grow increasingly more popular and efficient, overall prices continue to drop making them accessible to a wider base of consumers.

Due to improvements in manufacturing and easements in shipping procedures, solar prices have fallen by more than 65% percent in the last ten years. This reduction in price is explained in simple terms by Richard Swanson of SunPower. He states that new industries face major learning curves at their start.

As they improve and round these curves, prices fall. He estimates that the price will drop by 20% for every doubling in global solar capacity.

Top 7 Factors Affect Solar Panel Efficiency 

There are many factors that impact efficiency and most of them should be taken into consideration at the time of purchase and afterwards. Some are as simple as just keeping the panel surface clean will have a huge impact overtime. 

  • Temperature 
  • Locations
  • Weather
  • Angle
  • Type of Panels & Cells
  • Shading Sensitivity
  • Maintenance


north dakota winter

Temperature has a positive effect on photvoltaic cell efficiency due to the nature of semiconductor material.

Panels are tested at 25 °C, and ideal operating temperatures are between 15-35 °C. The efficiency increases when the temperature drops and decreases in higher temperatures as the voltage between cells drops.


Where you are and how much sunlight your region gets on a annual basis do matter.

Getting sunlight is the number 1 factor for the solar panel to work. Without it, nothing works.

You can't really control the weather or simply just move to the region with max sunlight, but you can maintain it to your best ability. Learn how to maintain solar panels here.


Cloudy skies are not ideal for producing consistent solar power especially when its consistent in your region.

In addition dust storm, snow, dirt, storm, tornado , hail and other mother nature factors that can prevent solar panels from working at its peak performance and even damage them.

Shading Sensitivity

Total or partial shading conditions have a significant impact on the energy delivering capability that lead to lower output and power losses.

Cells in a solar panel are usually connected in series to get a higher voltage and therefore an appropriate production of electricity.

However, when when shading occurs, this structure presents some limitations.

In fact, when a single solar cell or the whole panel is shaded, the current of all the units in the string is shaded. This also have to do with how solar panels are connected either parallel or series solar panel connection.

To prevent the loss of energy, the installation usually includes bypass diodes to generate energy at a reduced voltage.

Sun Exposure / Angle

Panels should be facing the direction of maximum hours of sun exposure for maximum absorption to increase output.

When installing the solar panel please include adjustable angle to follow the sun.

Types of panel

The most common types of panels include

  • Amorphous (Most efficient, better in low light)
  • Polycrystalline (Least)
  • Monocrystalline (More than poly for smaller size & same output)

To learn more about them click here.

Number of cells

The number of cells in your solar panel directly impacts efficiency.

The most common solar panels have photovoltaic cells arranged in a configuration of the following:

32, 36, 48, 60, 72 and 96

Most residential solar panels today are among: 60, 72, and 96.

A 96-cell panel will have a larger surface area to absorb light than a 60- or 72-cell panel.

More light absorption leads to more energy output.

Panel Inspection and Maintenance

cleaning solar panels

Keeping up with your annual solar inspections and maintenance appointments can help to ensure you remain at the highest level of output and efficiency, and to prevent costly damage if remained unchecked.

While most solar panel manufacturers recommend cleaning your panels twice a year that lead to a 3-5% increase in efficiency.

For practicality, clean every 6 months and clean as much as can if you feel the panels are constantly getting dirty.

These include:  Removal of dust, dirt, bird poops... etc off the glass surface to increase / restore performance.

How Does Efficiency Affect Your Wallet?

The Federal Solar Tax Credit

The EPA and the Department of Energy offer tax credits for consumers who install solar-powered systems.

Solar Renewable Energy Certificates (SRECs) are a solar incentive that allows homeowners to sell certificates for energy to their utility. It exists because the renewable portfolio standard state laws requires a specific percentage of their electricity from renewable resources.

On average, A homeowner can one SREC for every 1000 kilowatt hours (kWhs) produced by their solar panel system. An SREC can be worth over $300 in certain states.

If you live in one of those states, you can benefit from it. Click here to see the states.

How Does Solar Pay for Itself Over Time?

Over time, your solar panels will pay for themselves to reduce your electric bill as well as rebates and incentive payments.  (assuming you have everything in order)

However, you must first make sure your financial situation is in order to make sense of your home solar project.

The worst you can do is take out a loan ($15k - $20k) to install solar panels on a house that hasn't even been not paid off, where you might save a lot on the electric bill, but the interest is killing you.


Solar panel industry is booming and the efficiency of solar panels have significantly risen in the last few years. It's reasonable to predict the industry is on a positive growth trajectory to make it even more mainstream.

To keep your solar panels performing at their peak, the efficiency over time can be affected by:

  • Temperature 
  • Energy Conversion
  • Locations
  • Angle
  • Type of Panels & Cells
  • Shading Sensitivity
  • Operation
  • Maintenance