How Often Should I Clean My Solar Panels?

How Often Should I Clean My Solar Panels?

One of the relatively minor side effects of the wildfires in California is the layer of dust and ash that has coated virtually every outdoor surface — including over one million homes with rooftop solar panels. So there are literally millions of people wondering: “Should I clean my solar panels?”

Fortunately, with today’s accurate solar monitoring systems, a system owner can actually determine the energy lost from dirty solar panels — and calculate the savings that can be achieved by cleaning them periodically.

Wind-blown dust and dirt is the source of most soiling on solar panels. Just like your car or your windows, the dust accumulates on the surface and builds up over time. If you’re in a dusty area like a farm or near dirt roads, this dust accumulation may be worse. Pollen from trees is another source of solar panel soiling, particularly in the spring. Some people talk about cleaning up after birds, but bird debris is usually not a problem unless your name is Hitchcock and you live in Bodega Bay.

When solar panels get dirty, photons from the sun are absorbed or reflected by the dirt instead of being converted into electrons — thereby reducing system output. The amount of output decline varies based on the location of soiling on the panels and the thickness of the soiling layer.

Heavy rains do an OK job of cleaning light dirt and debris off solar panels. But if you are in a dry and dusty are, if you can see a layer of ash on your solar panels, or if your solar monitoring system shows a significant drop off in energy product, it may be time to get your panels cleaned.

Please Listen Up to this week’s Energy Show as we walk through the performance implications of dirty solar panels, and describe the best ways to safely and effectively clean your panels (hints: never hose them off, use deionized water and an environmentally safe cleaning solution).

Solar System Upgrade

Solar System Upgrade

With the gradual improvements in solar technology over the past 15 years, many early solar customers are considering a solar system upgrade. Some people want to add more panels because their electrical demand has increased. Some people have inverters that are past their warranty. Some people want better system monitoring. And some people are doing a home renovation and want to re-use their existing panels.

Not surprisingly, the most common reason for an upgrade is to add battery backup capabilities to keep their lights on and their fridge cold. Systems based on older string inverter technology (and some microinverters), need an inverter upgrade to be compatible with the latest lithium ion battery technology.

Thinking back on the equipment we installed 20 years ago to today, a lot has changed. Solar panel efficiency has gone from 14% to over 22%. Inverter efficiency has gone from 93% to 99%. Monitoring (while still somewhat complicated) is now standard. And, perhaps most importantly, battery storage systems are automatic, more reliable and have 10-year warranties.

Remember, the 26% tax credit applies to solar and battery upgrades. So if you are thinking about a solar system upgrade, are about to re-roof or do a home renovation, or want to add battery storage, please listen to this week’s Energy Show. We will review the latest solar technology, detail what’s involved in upgrading, and provide useful tips to ask your solar installer so that you get the best solution for your home.

Cleaning Solar Panels

Cleaning Solar Panels

When a business or homeowner gets a new rooftop solar installation, the second question they always ask is “how often do I need to clean my solar panels.” We’ll answer that question on this week’s show — taking into account the different effects of rain, dust and electric rates. BTW, the first question people always ask is “how do I read my electric bill;” but that’s a topic for another show. (more…)

Upgrading Your Solar System

Upgrading Your Solar System

Over a million buildings in the U.S. have rooftop solar. These systems are extremely reliable: solar panels are guaranteed for 25 years, and inverters are guaranteed for 10-25 years. Our experience as a contractor since 2001 bears out the terrific reliability record of rooftop solar. (more…)

Upgrading Your Solar System

What Do You Do When Your Solar Inverter Dies?

We’ve been installing rooftop solar panels and solar inverters for almost 20 years. Solar panels are incredibly reliable – guaranteed for 25 years with an expected life of over 30. But solar inverters (the box of electronics that converts DC solar power to AC household power) have shorter warranty periods – typically 7 years for older models, and 10-12 years for newer units. On this week’s Energy Show we’ll talk about what to do when your solar inverter stops working. (more…)

How Often Should I Clean My Solar Panels

How Often Should I Clean My Solar Panels

When someone gets a new rooftop solar installation, the second question they always ask is “how often do I need to clean my solar panels.” We’ll answer that question on this week’s show — taking into account the different effects of rain, dust and electric rates (BTW, the first question people always ask is “how do I read my electric bill;” but that’s a topic for another show).

Rooftop solar panels get dirty primarily from wind-blown dust and pollen. Birds are usually not a problem unless your last name is Hitchcock and you live in Bodega Bay. As panels get dirtier, their output declines. A small amount of soiling — say a light dusty film — may only cause a 5 percent output decline. However, when panels get very dirty — perhaps in an agricultural area or location that does not get regular rainfall — the output decline can be greater than 20 percent. A good heavy rainstorm will usually wash away most of the accumulated soiling.

I use the term “usually” because on panels that are tilted at about 5 degrees or less, the rain may leave a puddle of muddy debris along the lower edge of the panel. When this puddle dries, sometimes a thick layer of dirt accumulates along the lower row of cells (sometimes moss and weeds may even grow in these areas). Depending on the design of the system, this small accumulation of dirt can cause a very significant decrease in output.

So the answer to the question: “how often should I clean my solar panels” really depends on five factors: your location (does it rain regularly or only during certain months), the tilt angle of your panels (steeply tilted panels tend to stay much cleaner than panels that are close to horizontal), the amount of wind blown dust, your electric rate (if your electric rate is high then it is more worthwhile to clean your panels), and the cost to clean your panels. For more about cleaning your solar panels, please Listen Up to this week’s edition of the Energy Show on Renewable Energy World.