Removing Algae From Solar Panels (9 Steps)

Algae are nature’s most prolific organisms and thrive on damp, sunny surfaces. The surface of solar panels appears to be smooth to the naked eye but at a microscopic level presents algae with a textured surface often covered in dust, soot, and dew.

Solar panels must be cleaned every three months to maintain their optimal efficiency. A drop in efficiency of twenty percent can be expected after three months. Cleaning the algae and dirt buildup every three months will prevent lichen growth and maintain solar efficiency.

When planning to install solar panels on rooftops or ground-mounted arrays, consideration for the cleaning and maintenance of the panels is essential. The solar array must perform optimally during its thirty-year operational life to:

  • Generate the optimal amount of solar power
  • Recover the initial investment in as short a period as possible
  • Maintain optimal heat dissipation capacity
  • Maintain optimal operational life

Algae growth on solar panels will happen and lead to the development of more hardy and difficult to remove growths such as lichen. Let’s review how you can avoid algae growth and how to clean algae growth effectively.

How To Clean Your Roof Panels Of Algae

If you clean your solar panels frequently, gently, and use an algaecide spray to deter growth, the cleaning task becomes more manageable and less time-consuming. A bucket of water, a soft-bristle brush, and a squeegee on an extendable handle are all needed to keep the panels looking new.

  1. Make sure that you have safe access and footing on the roof to allow you to clean the solar panels.
  2. Wear a safety harness and shoes with good grip when working on the roof. Cleaning the solar panels is best done before it gets too hot in the day, ideally before 9 am or after 4 pm.
  3. Start by dry brushing the excess dust, bird droppings, and debris on the panels.
  4. Spray on a mild mixture of soapy water on each panel and use the brush on the extendable handle to create lather on the entire surface of each panel.
  5. Using clean water from the garden hose, gently rinse the lather from the panels and then use the squeegee to remove the excess water.
  6. Work on one or two panels at a time, and don’t allow the lather to be dried out by the sun.
  7. Rinse and wipe off the excess water before the sun causes it to evaporate.
  8. Prepare a solution of one part “Wet & Forget” to five parts water in a spray-on bottle. Spray the solution over the surface of each cleaned panel and allow it to dry on the panel surface.
  9. This algaecide will kill off any remaining algae spores on the panel’s surface and inhibit new algae growth.

The secret to making the task of cleaning your solar panels quickly and with the minimum of effort is to do it frequently, thoroughly, safely, and gently. If left for too long, algae growth will give other growths such as lichen a foothold on the solar panels.

Cleaning off lichen is far more demanding and time-consuming than the gentle cleaning required to remove algae, dust, and debris.

Why Does Algae Grow On Solar Panels?

Solar panels appear to be smooth glass, but the surface at a microscopic level is rough and will trap soot and dust and create a growth medium when it becomes wet with precipitation. The algae spores carried by the wind will take hold in the nutrient-rich dirt buildup on roofs and solar panels.

The algae will thrive on a dirty solar panel’s most nutrient-rich surface and quickly bloom into a thriving colony. During the early stage of growth, the algae will be invisible to the naked eye and only manifest once the green growth becomes visible on the aluminum frame of the solar panel.

Solar panels are only about 23% efficient at converting incident solar radiation into energy. A further twenty percent reduction in dirt buildup and algae growth should be avoided by frequently cleaning the solar panel surfaces.

The better you develop your technique and the supporting tools to get the job done, the more you will benefit from your solar installation. Try to establish your cleaning method by using as little water as possible.

See also: Clean Solar Panels (When, Where, How)

Remove Loose Dirt

Many of our sunny regions are affected by drought and forest fire which makes cleaning our solar panels even more essential. Use a battery-powered leaf blower and a soft-bristled broom to remove loose dirt and debris.

Use a Scraper

Use a plastic scraper to remove the stubborn bird droppings taking care not to scratch or scour the glass surface of the solar panels. Apply soapy water with a garden hand pump and the soft broom to work the soapy water into a lather on the glass.

Hand Pump

Use a second hand-pump or garden with fresh water to gently spray off the soap and dirt from each panel. Take care to limit your use of the garden hose to preserve water.

Cleaning brush on a solar panel

What Are Good Cleaning Agents For Solar Panel Surfaces?

A clean water rinse and dry can follow soapy water to wash the dirt and growth off the panels. Use vinegar or isopropyl alcohol (IPA) on a soft microfiber towel to deep clean the glass and aluminum surfaces of the solar panels.

Mixing a gallon of clean water with a cup of vinegar is an excellent solution to wash and scrub off the solar panels. Always rinse off the panels with clean water afterward, as vinegar is a weak acid and will corrode aluminum.

Commercially available products such as Wet & Forget” or “Spray & Forget” are designed to eliminate algae, lichen, and moss growth on exterior surfaces. Follow the manufacturer dilution and application recommendations.

A high-pressure washer can also be used to clean solar panels as they use water sparingly and have adjustable spray settings. Do not concentrate the high-pressure water directly on the solar panel surface or MC-4 connections.


  • – DIY – How to Clean Your Solar Panels the Easy Way (if you dare climb on your roof safely)
  • – Dirty vs. Clean Solar Panel – Power Output Comparison and HowTo
  • – Wet and Forget

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Elliot has 20+ years of experience in renewable technology, from conservation to efficient living. His passion is to help others achieve independent off-grid living.

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