A storm blew through our region last night, and man, it was windy. It was the typical wet ‘n wild pacific storm track that we get in the Northwest this time of year. I do love the Fall – college football season of course – but it’s nature’s changing colors, filtered light, and the chill in the air I appreciate the most.
We live on Arnold Street, a scenic place of creeks, trees, moss, wildlife, and no sidewalks. In times past, our
neighborhood was considered the woods just outside of town, although we’re just seven miles from downtown. I’ve seen data that shows Arnold Creek as the most canopied neighborhood in all of Portland.
The street itself parallels a stream that bears its name and it runs through a dense forest until it spills into Tryon Creek SP (640 acres) which is at one end of our street. The neighborhood butts up against Mountain Park, so we have elevation and hills to contend with, and our house is on a slope surrounded by tall evergreen trees of all kinds. We feel fortunate to live here, except on a day like today. In the aftermath of this storm, our neighborhood is a disaster with broken tree limbs, downed power lines, tree leaves and debris scattered everywhere.
For rooftop solar collection, this is an especially difficult time in the Pac Northwest. Trees, hills, shade, and storms are enemies of solar efficiency, but even without those things, solar resource is something we sorely lack in the Willamette Valley this time of year. Last winter I lamented and wrote a piece called Winter is a time of doubt … http://solarflareblog.com/?p=1772
It is common knowledge that when choosing a site for solar collection, one must consider sites with minimal tree coverage and free from shadowing by chimneys, dormers, power lines, structures or hills. A professional solar contractor will conduct an assessment and locate the best solar collection site on your property, but since we live in a forest-like setting, this was a difficult proposition. However, we sited our solar array in a place that allowed for over 75% total solar resource fraction (TSRF) [required by the Energy Trust of Oregon for their solar rebate program]; which is a small building in the backyard unattached from our main residence where we placed our 20 Sanyo HIT solar modules.
Tree debris, pollution, dust, tree sap, pollen, soot and other fine particles, build up an opaque layer of grime on the panels. Even bird droppings can significantly reduce the power output by shading the silicon cells under the protective glass layer. In places where there is abundant rainfall, solar panels require relatively little cleaning or maintenance. In fact, I’ve hosed off our solar array only four times over the past two years. See Keep ‘em clean … http://solarflareblog.com/?p=1079.
In colder climates solar electric modules tend to self-clear snow and most dirt and grime is removed by the melting snow or rain. In the Southwest region of America, it rains so infrequently that this just isn’t an option. Besides, the desert dust mixes with the oils and dirt on the road then is picked up by the winds and deposited on residential rooftops. So, to clean requires more maintenance and in many cases a biodegradable “earth friendly” detergent is used to remove the oil-soaked grime from the panels.
I’ve never used a cleaning detergent. I simply spray off our panels with a garden hose, which takes only about six minutes from start to finish [including the time it takes to clean out the rain gutters!]
I’m careful to spray under the modules to prevent debris from accumulating as it can reduce airflow and might cause water to back up in a severe rainstorm. I was also sure to spray the trough – the bottom side of the panel – where pine needles and grime tend to gather. I didn’t even need to use the soft brush this time.
Extreme caution should always be taken when on a roof or a
ladder. Consider hiring a professional service to perform regular cleaning if
your home is multiple stories, or if you cannot use a hose from a distance more
than 50 feet. Use a soft brush on a pole so that there’s no chance the panels will be damaged by any weight being placed on them. Although the tempered glass surface of a module is quite durable, it will break if you walk on it. Any crack in a tempered glass usually requires replacement of the entire module … and this is something you don’t want.
Why should I clean my solar panels … I thought they’re “maintenance free”?
You paid good money for this system and you want maximum output of course. Dust, bird droppings, tree debris and the like can accumulate, thereby reducing module efficiency by 20% or more. The only maintenance most require is a semi-annual washing. For regular dust accumulations, you can simply hose the modules off, but if there’s significant accumulation of tree sap or other residue, cleaning with a sponge or squeegee, using a mild soap and water solution, may be required.
Will cleaning my solar panels invalidate my warranty?
No, just the opposite, regular maintenance of your solar panels will protect your warranty and is recommended by the manufacturer. Most solar electric (PV) modules are guaranteed for 25 years and regular cleaning will keep your warranty valid.
Is getting my solar panels cleaned by a professional expensive?
Pricing is based on the size of your system, accessibility to your solar panels, water source and power. For most residential applications the one-time cost is between $40-$60, however many solar contractors offer discounts for quarterly or monthly cleaning contracts, which is not a bad deal if you live in a dusty region of the country.
by Joyce Kilmer (1886–1918)
I think that I shall never see, a poem lovely as a tree.
A tree whose hungry mouth is prest, against the sweet earth’s flowing breast;
A tree that looks at God all day, and lifts her leafy arms to
A tree that may in summer wear, a nest of robins in her
Upon whose bosom snow has lain; who intimately lives with
Poems are made by fools like me, but only God can make a