How to Clean Solar Panels: Domestic and Commercial

Getting the maximum energy from solar panels relies on many factors, like their cleanliness.

When a layer of dirt builds up on the protective glass layer of your PV system, no matter how strong the sunlight is, it struggles to reach the solar cells.

Receiving little or no sunlight directly impacts the amount of electricity that solar arrays produce. Knowing how to clean solar panels ensures the year-round maximum efficiency of your system.

Cleaning domestic solar panels require no specialist equipment or materials; water and a sponge does the trick. However, due to their precarious positioning, only undertake the task if you feel safe.

Agricultural, commercial, and industrial solar power systems require more frequent cleaning due to their size and situation.

Scheduled cleaning is often included as part of your maintenance plan; otherwise, professionals offer cleaning services.

Why Should You Clean Solar Panels?

dirty solar panels

Solar power works by harvesting energy from the sun via photovoltaic cells; before converting it into clean and reliable electricity. The system is simple yet can only work to its full capacity if sunlight can get to the cells.

A plethora of things gather on the glass screen of each PV panel: Algae, debris, dust, moss, dreaded bird droppings, or a combination of them all build-up an impenetrable layer.

Anything that blocks the sun's rays decreases the possible energy yield, therefore, reducing savings and extending payback time.

How Often You Need to Clean Solar Panels

The frequency at which solar cleans require cleaning is primarily based on type: domestic or commercial.

Domestic Solar Panels

Domestic solar panels might never need cleaning.

Design factors in most conditions and installation take care of the rest. For instance, rain is nature's way of keeping the panels clean. The angle at which each cell is installed ensures the majority of dirt washes away with the rainwater.

In States with very little rainfall, homeowners still find that the occasional downpour is enough to keep their solar system clean.

Properties close to heavy industry, agriculture, factories, or free-ways attract more dirt and heavier pollution. Again, unless you live in a state renowned for drought conditions, rainfall is most likely sufficient to keep solar panels clean.

Commercial Solar Panels

tool designed to clean solar panels

Commercial solar panels should be cleaned regularly. By their nature, they are in areas where dirt and pollution are higher.

Potential financial losses are greater the bigger the system gets.

Loss of production affects the length of payback time, expected savings on utility bills, and any potential earnings.

Most commercial set-ups include a maintenance plan; it is an annual equipment and performance check that often includes a full system wash.

There are solar panel cleaning services available if your installer doesn't provide them.

How to Know When it's Time to Clean Solar Panels

There are three reliable methods:

  1. Physically go outside and check. If safe, use a ladder and look for signs of build-up or dried on bird droppings.
  2. Check your monitoring system. Are your panels performing as expected for the time of year, or has there been a drop in production? It could be a warning sign that it's time to give them a clean.
  3. Subscribe to a monitoring service offered by your installation company at the time of set up. For a small fee, payable monthly or upfront, they continue to monitor your system to ensure it is performing to its full capacity at all times. Not only does this pick up on issues before they occur, but it also saves you money and extends the lifespan of your PV system.

For commercial solar arrays, all of the above criteria apply but it is also worthwhile scheduling a regular annual or bi-annual clean, depending on your business and the location of the panels.

How to Clean Solar Panels

Let's assume that you are confident in tackling the job yourself and have a safe structure from which you can securely reach the panels. If your panels affect production levels or have unsightly stains on them, it's time to wash them.

Note: Before performing any maintenance task yourself, ensure you read the manufacturer's installation, maintenance, and safety documentation. Doing these tasks yourself could cause personal injury, harm, or loss. Avoid using harsh chemicals, industrial-grade cleaning agents, or sharp instruments as they may void your warranty.

cleaning solar panels

Time of Day

Solar panels inherently get hot. Leave any cleaning until the sun goes down, or better still, early in the morning before the brightest sun is overhead.

Follow the Guidelines

Refer to the instruction manual left by your installer, or head online to find their recommendations.

They might have a particular trick up their sleeve to return the panels to their best. More importantly, there may be products or methods that you should avoid for fear of invalidating any warranty.

NO Pressure Washing

The temptation might be great, but high-pressured water creates micro-cracks that significantly affect yield; Avoid do so at all costs.

Just Water

Tap water from a bucket or hose is best and usually sufficient enough to do the trick. Some professionals use deionized water although it isn't essential.

If you choose to use detergent, a squirt of dish soap is sufficient. Harsher chemicals react with the panels and harm them.

Granted, car wash soap could be considered a better alternative as dish soap does contain micro-abrasives.

Non-Abrasive Cloths

A sponge or cloth is the only other piece of equipment you need to gently wipe away dirt. Instead of over-reaching, use a mop to reach the furthest points.

Mop heads get into all corners, including the bottom of the frame where debris sometimes collects, left behind by the rain.

Don't apply too much pressure; Use gentle rubs in a circular motion.

Is it Worth Cleaning Solar Panels?

Domestic solar energy systems perform better when they're clean, but only by a small margin.

If a typical 5kw system generates more power than an average household uses, is cleaning the panels worth the time and expense?

A 2% yield improvement compared with before and after washing panels equates to an overall saving of around $20.

It's for you to decide whether it is worth the trade-off, especially if you're paying a professional more than the actual savings.

Figures inflate when dealing with a commercial system. Studies show that energy yields significantly improve, by up to 10%, based on a large system cleaned 12-months previously.

The earning and potential savings increase accordingly, while payback time decreases.

Final Thoughts

Depending on where you live, precipitation does a wonderful job of cleaning PV systems. Most are positioned to accommodate for this fact.

However, if you live in a location that is prone to less rain-fall, the cleaning process is relatively simple; use water. However, using a mop and towel as well as a dish detergent or car wash soap can help to break down debris.

Check with your installer before-hand to see if regular maintenance tasks like cleaning are included.

Dillon Clayton
Dillon is an Energy enthusiast. The goal of his posts on Energy Follower are to help inform people of the energy options around them based on impartial research.

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