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Solar panels offer an excellent return on investment, and the savings you can expect over their 25- to 30-year service lives are much higher than their upfront costs. However, there are some performance issues that can affect solar panels, and they will undermine your savings if left unattended. Fortunately, most of these problems are relatively easy to solve, and major issues are covered by a warranty if you purchase high-quality solar panels.

In this article, we will discuss some common issues that may affect solar power systems, as well as how to solve them. By making sure that your solar panels stay productive, you get consistent savings each month and can shorten your solar panel payback period.

When the electricity output of solar panels is lower than normal, there are many possible causes. However, the following are some of the most common:

It’s important to understand that solar panels will rarely generate their nameplate wattage — they are tested under ideal laboratory conditions, which are not achieved in rooftop installations. Solar manufacturers use the same testing conditions to allow a direct comparison of their products, but the actual electricity output depends on site conditions. You can have two homes with 360-watt solar panels of the same brand, and their electricity output can vary widely due to factors like local sunshine, roof orientation and ambient temperature.

Also, keep in mind that inverters are often sized smaller than the solar arrays connected to them. This is an economic decision: solar panels will rarely reach their peak output outside of laboratory settings, and an equally-sized inverter will rarely operate at rated capacity. Instead, the inverter “clips” the occasional solar power peaks that exceed its wattage.

The capacity relationship between a solar array and its inverter is described by the DC-to-AC ratio, also known as the inverter load ratio or ILR. For example, a 10-kW solar array with an 8-kW inverter has a DC-to-AC ratio of 1.25. This is designed to help homeowners save money on solar panel installations, but it can also occasionally lead to a lower-than-expected solar panel output.

If you suspect that your solar panels are suffering from low productivity, the first step is identifying the exact issue. You could be simply dealing with seasonal variations, or your solar panels could be in need of cleaning. However, your solar PV system could also be suffering a major malfunction, which requires professional attention and possibly a warranty claim.

Solar panel inverters from leading brands like Fronius and Sungrow come with built-in monitoring systems and mobile apps. You can check the daily output of your solar panels from a smartphone, and performance issues are reflected as a drop in the daily kilowatt-hour output. When this happens, you can start by ruling out normal variations in productivity and problems that are easy to fix, including:

Solar panels can be expected to lose productivity over time, but this happens slowly — a sudden drop in electricity output normally means trouble. Keep in mind that the best solar panels lose less than 0.5% of their capacity each year. So if your system generated 10,000 kWh during its first year of operation, you can still expect around 9,950 kWh the second year.

You can also detect solar panel issues by keeping track of your electricity bills, but note that higher bills can have several causes. For example, if you live in a place with hot summers, you can expect air conditioning to increase your bills during that time of the year.

The best option is having a dedicated monitoring system for your solar panels, to obtain measurements that are not affected by other electrical devices. Older inverters may lack metering functions, but there are monitoring systems that offer compatibility with multiple inverter brands. Modern inverters can detect many types of faults on their own, and they will diagnose exactly what is happening. This makes troubleshooting much easier.

Many solar power issues can be fixed with cleaning and checking if there are loose connections or tripped breakers. However, some problems are a bit more challenging:

As mentioned above, there may be cases in which your monitoring system displays zero production but your solar panels are working normally. Or, there could really be an issue that prevents electricity production. In both cases, you should contact your solar PV system provider for an inspection. Waiting for the next power bill is not recommended, as you may get an unpleasant surprise.

Electrical faults and other major malfunctions are rare if your solar power system uses high-quality components installed by professionals. However, these issues can happen even with the best solar products.

Here are some key things to know about solar panel output issues:

Generally, the company that installed your solar panels will help with warranty claims and component replacements if necessary. However, this only applies if you’re dealing with professionals, which is just one reason it’s important that you make sure you purchase your solar PV system from a qualified provider. If you’re interested in getting connected with a professional solar installer in your area, fill out the form below.

All EcoWatch solar companies are pre-vetted for your convenience.

Even if your solar panels are working normally, there are many things you can do to use their electricity more efficiently and increase your savings. Adjust your energy consumption habits and program your appliances to operate around noon whenever possible, as this is when the sun is directly overhead. Avoid using appliances in the evening, when many electricity providers are charging their highest tariffs. Also, make sure your solar panels are cleaned regularly, or their kilowatt-hour output could drop significantly.

Leonardo David is an electromechanical engineer, MBA, energy consultant and technical writer. His energy-efficiency and solar consulting experience covers sectors including banking, textile manufacturing, plastics processing, pharmaceutics, education, food processing, fast food, real estate and retail. He has also been writing articles about energy and engineering topics since 2015.

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