Solar Panels Efficiency Over Time

Are you planing to go solar, but you’re afraid that over time your panels will generate less and less power?

Well, if this is your concern, just look at the standard warranty provided by solar panel manufacturers, which says that the panels will work fine about 25 years, and even after that they will generate at least 80% of their initial output.

Installing a solar panel system that can lower your monthly energy bills is a long-term commitment because even if the price of solar went down in the last decade and the federal tax credit is still available, the price paid for the system is still quite high.

In 2011, a standard 6 kW PV system had a price of about $50,000, however, today (at the end of 2019), we can buy a similar system for only about $18,000 ($13,000 after the federal tax credit).

The price of solar decreases year after year, but what about the efficiency of the panels?

Before investing more than $10,000 in a new solar PV system, I’m sure that you want to know how much efficiency will your panels lose over time.

How Much Efficiency Do Solar Panels Lose Over Time?

Have you heard about the degradation rate of solar panels?

Degradation rate refers to the rate at which solar panels lose efficiency over time.

There are different types of solar panels on the market today, but on average, each solar panel loses between 0.5% and 1% efficiency each year.

This means that a solar PV system that today has an efficiency of 20%, will still operate at 15% efficiency after 25 years of usage.

I would not be very afraid of the fact that my solar panels are losing some efficiency each year, because yes, energy bills will become more expensive over time, but at the same time, the appliances and all the electric devices used in the house today are also becoming more and more efficient, which means that they will consume less power.

The Efficiency of the Panels After 25 Years of Use

A solar PV system that works today at 20% efficiency, will still operate at 15% efficiency after 25 years, but our energy bills will also decrease over time because the devices used in the house are becoming more efficient.

Solar panels have no moving parts, and this means that they can survive for decades sitting on your roof.

The warranty guarantees that the panels will work for 25 years, but be sure that the panels will still produce energy (with a reduced efficiency) way long after that.

Ways To Extend The Life Of Your Solar PV System

In order to give your solar PV system a chance to last more than 25 years, you need to take good care of the panels, inverters, chargers, batteries, etc.

The solar panels used by your PV system will last much longer than the other components of the system (inverters, chargers, batteries, etc.), but to be sure that they will serve well more than 25 years, you need to keep them in very good shape (clean) as much as you can.

Keeping your panels clean is vital if you want to get the most out of your solar PV system (clean panels produce 26% more energy than slightly dirty panels).

How to Keep Solar Panels Clean?

Never clean your panels in the middle of a sunny day because they will be very hot and the cold water used to clean them may damage their structure.

Always clean the panels in the morning or in the evening, and use only tap water (preferable soft water), some liquid soap (if needed) and a very soft bristle brush.

Use a Garden Hose

Start by spraying down the panels to loosen up and remove some of the larger particles (use a garden hose not a pressure washer).

Use a Brush

With the panels wet, take the brush soaked in soapy water and start to lightly brush the surface the entire surface of the panels.

Rinse the Panels

Thoroughly rinse the panels using the same garden hose and tap water, to remove any soap residue.

Inspect the Panels

Inspect the panels to see if they are clean and have a smooth surface, otherwise wash them again to remove any pollen build-up, bird or bat droppings, etc.

Your panels will become clean again only when they have a smooth surface.

Advice

Be very careful when walking on the roof to clean your panels because a wet or soapy surface can be very slippery, and you don’t want to fall from the roof and risk your life.

If the panels are located on a pretty high roof or in a more difficult place, it is best to hire a company specialized in cleaning solar panels.

In normal conditions, you can clean your panels once a year, however, if you live in an area with almost no rain, but full of dust and maybe birds and bats, you have to do the cleaning more frequently.

Inverters

An inverter is usually replaced every 10 years, however, today, the grid-tie inverters have a 10-year warranty that can be upgraded to a 20 to 25-year warranty, which is very beneficial for the owner.

It is better to choose the extended warranty because inverters usually stop working after 10 to 15 years, and if you have an extended warranty, you will replace the old inverter with a newer and better one.

Off-grid inverters have a shorter warranty (1 to 5 years), which can be extended up to 10 years.

However, before purchasing the extended warranty for your off-grid inverter read the details very carefully because you don’t want to pay an extended warranty that only covers some of the parts and not the cost of the labor to replace the inverter.

Batteries

You can significantly lower your energy bills only by installing a battery system to store the energy produced by your PV system during the day.

If you only send back into the grid the excess energy produced by the panels during the day (when your household consumption is also low), the utility company will pay you only a fraction of the money paid by you to receive the same amount of energy from the grid.

It is much better to have a battery system attached to your solar PV system because instead of sending energy in the grid, you can save the energy and use it during the evening, the night and maybe even in the next morning.

This way you will longer consume energy from the grid in the sunny days because the energy produced during the day will be stored and used when the sun is down.

A larger battery system can store energy for several days, and will also provide energy even in case of a blackout in the grid.

Grid-tie Solar Systems Don’t Need a Battery Pack

A grid-tie PV system does not need a battery system, however, a battery system is vital for off-grid systems.

For any owner of off-grid systems, battery maintenance and replacement represents one of the main expenses because both lithium and sealed lead acid batteries need to be inspected a couple of times per year.

Batteries usually come with a warranty that covers only the first 3 to 10 years, and if you don’t know how to care for your battery system, it may fail in its first year of usage.

Lead acid batteries require a full charge after being used, and they can’t stay without being recharged for a longer period of time (to avoid a permanent damage of the battery).

High-quality deep cycle batteries for off-grid applications can last between 5 to 15 years (depending on how you maintain them).

To be sure that your deep cycle battery is always in a good shape and has a chance to live up to 15 years, it has to be installed by a professional that will also teach you how to take care of it.

A balanced off-grid system that is initially designed with the required amount of battery capacity for the installed solar capacity, and a quality inverter with proper output, will always live longer.

Final conclusion

The Sun is a free source of light, heat and clean electricity for us, and by installing a PV system that can cover our energy needs and is also well maintained, we can say that we are set for the following decades because we have our own power plant installed on the roof that produces free energy for us and for some of our neighbors.