The Energy Show: By Barry Cinnamon

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.

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.

If you have a large solar array at a low tilt angle in a dry climate with high electricity costs, our basic advice is to clean your panels once a year. Under these circumstances the additional electricity output from clean panels will be much greater than the cleaning costs. On the other hand, if you have a small array in an area that rains regularly, then it may only make sense to clean your panels every five years or so. Here in California it generally does not make a lot of sense to clean your panels in the late fall or winter during the rainy season.

Regardless of your circumstances, please make sure you clean your panels with soapy or treated water to prevent damage from mineral deposits. Contact your solar contractor or maintenance company if you would like your system cleaned professionally. For more about keeping your solar system operating at top efficiency, please Listen Up to this week’s edition of the Energy Show.

The Energy Show: By Barry Cinnamon

There are there are three market segment for solar in the U.S.: residential, utility and commercial. Based on some rough math, in 2018 we expect to install 5 to 7 million solar panels on homes in the U.S. In areas with high residential electric rates, paybacks are usually in the range of 4-8 years. But the utility solar segment is much larger: about 20 million solar panels will be installed by utilities in 2018. Utilities realize that it is cheaper to generate power with solar compared to coal or nuclear generation. Moreover, the combination of solar and batteries is projected to be even cheaper than natural gas in a few years.

The commercial solar segment has been growing, but has been challenged by a lack of efficient financing, slow decision making, and relatively high costs. But this market segment is poised to grow much more quickly in the coming years. Standardized lease, PPA (Power Purchase Agreement) and PACE (Property Assessed Clean Energy) financing is now available. Cheaper solar panels, inverters and rooftop installation techniques are reducing up front costs. And commercial customer decision making is accelerating now that a number of national retailers (Costco, Staples, Target, Safeway), tech companies (Microsoft, Apple, Google), casinos and data centers have made rooftop solar a standard part of all their buildings.

Quite simply, the biggest advantage of rooftop solar to commercial customers is financial. As with the residential and utility segments, almost any commercial building can reduce their electricity costs by 20-40% (net of financing costs). Paybacks are in the range of 3-8 years, easy financing is available for both for-profit and non-profit businesses, and even tenant-occupied buildings with triple net leases can benefit.

As a result, the acres and acres of flat roof buildings around the country are destined to be put to work generating clean, renewable power. For more about commercial solar for businesses of all sizes, Listen Up to this week’s Energy Show.

The Energy Show: By Barry Cinnamon

These days you can’t watch TV, read a news story or listen to the radio without seeing catastrophic fires, hurricanes, and high temperatures. The world is getting hotter. To illustrate, Death Valley recorded the hottest month ever recorded on Earth. Temperatures averaged 108.1 degrees day and night, all of July 2018. That beat last year’s record monthly temperature. This is not just a U.S. only story, it’s a worldwide issue. During the month of July 2018 record high temperatures were set on every single continent in the northern hemisphere (it was winter in the southern hemisphere).

Politicians, policymakers and leaders all over the world created the Paris Climate Agreement in 2016 — which every country in the world joined except for outcast Syria. Syria stepped up to the Paris Climate Agreement in 2017 — and then during the same year President Trump withdrew from the Agreement. The U.S. is the only country in the world that is not a signatory of the Paris Climate Agreement, the intention of which is to avoid a likely slow motion global warming disaster. We have been euphemistically describing this problem as “climate change.” Yes, the climate is changing, and it is getting hotter. So I am back to describing this looming catastrophe as “global warming.”

There are a few scientists who still believe that this global warming is not caused by mankind, is part of a natural cycle, or is not really a problem (Iceland could be the new Costa del Sol). Nevertheless, according to ongoing temperature analyses conducted by climate scientists at the NASA Goddard Institute for Space Studies, the average global temperature on Earth has increased by about .8 degree Celsius which is 1.4 degrees Fahrenheit since 1880. Two thirds of the warming has incurred since 1975 at a rate of .15 to .2 degrees per decade. Natural processes are generally not linear — this warming is speeding up. We may be getting close to a tipping point at which global warming dramatically accelerates, flooding coastal areas and creating conditions so hot in many countries that humans can no longer survive.

Please Listen up to this week’s Energy Show as we share various scientific and media perspectives on global warming. It’s time to panic and act.

The Energy Show: By Barry Cinnamon

This week’s Energy Show is for solar power customers, contractors and inverter manufacturers who appreciate the need for reliable solar power systems. Surprising as it may seem, most solar monitoring systems are simply not up to the reliability standards of the panels and inverters they support.

The good news is that solar monitoring problems almost never affect system performance. Monitoring failures may indicate an inverter problem, but the panels and inverters are almost always working properly. In reality, the problem is with the communications somewhere along the chain – including the inverter, inverter gateway, home router, wireless connections (wifi, zigbee, cellular, etc.), internet connection and server-side software. Troubleshooting these monitoring and communications issues is one of the biggest hassles that contractors have — made more difficult by the fact that most installers do not have home networking IT expertise. As a result, many contractors have changed their inverter suppliers because of less than perfect monitoring hardware and software.

Going back to 2001 I’ve installed inverter systems from over a dozen companies. Not surprisingly, most of these inverters or communications systems are still running (including Trace, SMA, Fat Spaniel, Xantrex, BP Solar, Sharp, Fronius, SunRun, Enphase, SolarBridge, PowerOne, SolarEdge, JLM, Tigo). Although these inverter companies make great inverters, they are not necessarily software and communications experts. The end result is poor monitoring reliability and customer complaints, even when the inverters continue to operate.

To learn more about these solar monitoring issues — as well as my recommendations for long term monitoring reliability— Listen Up to this week’s Energy Show.