A Guide To the Efficiency of Dirty Solar Panels

Overview

To clean solar panels or not to clean?

The answer is in your energy bill.

With an overload of studies and claims around solar panel cleaning, it can be easy to get lost in the facts vs fiction.

The truth is, there are a number of factors that can affect the efficiency of your solar panels, and dirt can be one of them—but not always.

Here’s everything you need to know.

Does dirt impact my solar panels’ performance?

The claim is that dust, dirt, pollen and bird poo dropped onto solar panels can act as a block, reducing their ability to absorb maximum energy from the sun.

This is true, but rain also happens, and in many cases, it is enough to keep your panels reasonably clean.

If you live in a dusty area prone to droughts, your solar panels might cop a beating, so a quick clean could do wonders for your energy bill.

For those who don't get much dirt collecting on their roof and receive regular rainfall, sit back and let the rain take care of it for you.

What type of solar panels need cleaning?

The trick to finding out whether you need to clean your solar panel is by monitoring your energy bills and usage month-to-month.

If you're seeing a consistent decline in your solar panel's performance, despite no change in your usage habits, perhaps a clean is just what the solar doctor ordered.

Solar panels installed on flat surfaces collect and keep more dirt.

Because there are no downward angles, heavy rainfall can't completely wash away the unwanted rubbish.

Google conducted an experiment in 2009 to settle the matter once and for all: does cleaning solar panels really make a difference in their productivity?

The web giant found that cleaning their 1.6 MW solar farm in California doubled their output of electricity overnight.

Pretty impressive---until you dig a little deeper.

Google admits the exciting results only applied to the solar panels that were installed on flat carports.

They were also located opposite a sand field, making them more prone to collecting dirt.

Google's tilted rooftop solar panels were a different story, showing an insignificant difference in efficiency after being cleaned.

The tilted position allows dirt to wash away with rain.

Unless you're experiencing a drought, there's little impact on a tilted solar panel's efficiency when Mother Nature does most of the dirty work for you.

Is cleaning your solar panels worth it?

Yes and no.

Yes, if your solar panel is flat and recording a decline in its efficiency.

No, if your solar panel is on an angle and its performance is consistent.

Even if you haven't had rain in a while and your solar panels are slightly dirty, it should only have a minimal effect on the solar panels' ability to convert sunlight to energy.

By the time it rains again, you probably won't even notice the effects on your energy bill.

The verdict?

If it ain't broke, don't fix it.

How to clean your solar panel

Whether there's been a drought, dust storm, or an influx of birds overhead, you've concluded your solar panels need a clean.

The next step, cleaning.

It's much like cleaning the windows; all you need is a bucket of slightly soapy water and a non-abrasive sponge.

Stay away from high-pressure water sprays as they can do more damage than good.

Strong chemicals and laundry detergents can also cause damage to your solar panels.

Stick to natural soaps and soft sponges to avoid scratches and harsh chemical reactions.

Keep in mind the time of day.

It's no secret solar panels get really hot---thank you sun---so aim to clean them in the morning or night when temperatures are cooler.

You should also consider the safety aspect of cleaning solar panels.

Experts recommend staying on the ground and using a sponge on a long handle, as going onto the roof could be dangerous.

DIY or call a professional?

If you're concerned about the height of your solar panels, it's worth calling a professional.

Keep in mind the costs vs outcomes.

If you're only cleaning your solar panel because of a slight dust build up and temporary lack of rain, the amount of money you will lose on your energy bill until the next rainfall probably isn't worth hiring a professional.

If your solar panels are flat and losing efficiency, hiring a professional to clean them for you could be an investment towards your overall energy bill.

Final words

Deciding whether you need to clean your solar panels comes down to personal preference, but you can't argue with the numbers.

Monitor your energy bill and usage, keep track of your solar panel's performance after rainfall, and step outside to take a look at them if possible.

If you decide a clean is in need, contact your solar panel manufacturer.

They could offer discounted services or have cleaning advice specific to your type of solar panel.

At the end of the day, cleaning solar panels is a simple chore.

You can squeeze it in when you have time, but if you don't get to it, there's probably not much to worry about.

This guide is opinion only and should not be taken as financial advice. Check with a financial professional before making any decisions.

Paul Coughran is the General Manager of Emerging Verticals at Compare Club. Paul has over 20 years of experience across a wide range of industries including Banking and Finance, Telecommunications and Energy. Paul leads a team of trusted experts dedicated to helping individuals make informed decisions about their insurance and utilities needs.

Meet our energy expert, Paul Coughran

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