The endless struggle of humanity with birds...after we installed 2.4 kWe (6 panels) on the flybridge hardtop on Aquabelle, we luxuriated in 100% SOC batteries and surplus power sufficient to head the 35 gallon hot water tank provided we did it early in the day until...
I found the PV output was dropping by the day which was puzzling.
So I went up and had a look and found that seagulls had created a small guano island about the size of Nauru on the panels.
Further monitoring showed that the gulls found the panels the perfect early to mid morning place to warm their bums. Once the panels got hot in full sun, they pooped and pissed off. Like 10 or 15 of the buggers at a time. They did not do this on the hardtop, ever. Perhaps they enjoyed the view from the panels, dunno, don't care. They had to go!
Like other TF owners I began to look into options.
Lasers, OK, that sounds like a good start. For example,
Outdoor Bird Laser Control | BirdStoppers.com
There are seriously powerful agricultural anti-bird lasers available...
Bird Beam | Australia | Laser Bird Control Australia
but when I investigated, especially the University of Delft system, there as no actual data as to effectiveness, and they only work in shade or the dark. I didn't like the idea of broadcasting random laser firings at night, not to mention the risk to pilots, and the system was useless in the daytime (the only actual research was by a group in US NW that found in at at-sea trial that even direct hits on seagulls did not scare gulls away from active fishing nets/lines). Move on.
Many of the available gizzmos are not compatible with solar panels as they cast shade that interrupts power generation. So no to all the whirlies, DaddyLonglegs, motorized Marine Spinners, etc.
Then there are the acoustic devices. Is there anything other than anecdotal data for effects on gulls. Not that I could find and I looked hard and long.
Then there's humming tape. Now that was an idea worth trying, so I bought some, about $7 at Bunnings aka Home Depot in the US.
https://www.bunnings.com.au/jack-30m-pest-control-humming-tape_p3041148
The problem was that twisted, tensioned humming tape, well, hums, loudly. Humming tape is a great solution if you aren't on the boat much, so if you don't care about your live-aboard-neighbor and want a cheap solution, humming tape works. I gave it to another boat about five slips away so I couldn't hear it as he was under attack from starlings on his lifeline. It worked...until there was no wind, at which point it didn't. Still, nice try.
Then there are the electricals. The owner above who rigged 110V to his lawn system says it works. I believe him. I looked closely at the anti-bird "shock [similar to electric fence] tapes."
https://www.maintracgroup.com.au/products/shock-tape-kit-16-metre?pr_prod_strat=copurchase&pr_rec_id=4826133f4&pr_rec_pid=1374074994788&pr_ref_pid=1374063034468&pr_seq=uniform"]https://www.maintracgroup.com.au/products/shock-tape-kit-16-metre?pr_prod_strat=copurchase&pr_rec_id=4826133f4&pr_rec_pid=1374074994788&pr_ref_pid=1374063034468&pr_seq=uniform"]https://www.maintracgroup.com.au/products/shock-tape-kit-16-metre?pr_prod_strat=copurchase&pr_rec_id=4826133f4&pr_rec_pid=1374074994788&pr_ref_pid=1374063034468&pr_seq=uniform
Installed around the edges of the panels they wouldn't do much because the seagulls weren't landing on the edge. They were using my panels as an airstrip, landing in the middle.
What else? There are the foil streamers, CDs hanging by a cord. I could fly some of those from antenna adjacent to the panels, but they don't last long in the wind and I would need to festoon the area for it to deter gulls which are stubborn, stupid birds.
What about scary owls? We tried that on Pegasus, my boat in Berkeley CA. Pegasus is on a straight line landing approach from the end tie on K-dock in Berkeley that leads the gulls to the fish cleaning area for the guest charter vessels. We are about 1/3 of the way down from the outer end.
The gulls either overflew en route bombing as they went and ignoring the owl, or landed on its head and pooped on it. So I didn't have a lot of faith that an owl would have the slightest enduring effect on Aquabelle. I briefly thought about trying out the dead seagull deterrent (seriously, it exists
Dead Seagull Decoy - Visual Deterrent
but moved on in about 2 nanoseconds because the ad admits:
"Caution: Our Dead Seagull has been made to have the "dead" effect so that other birds sense danger. The wings on the bird are slightly skewiff so that it looks dead, this means the way the wings are attached to the body the feathered wings can be delicate, so we advise not to leave out in the wind and rain."
You couldn't make this stuff up.
By now, I was really pissed off and pooped out. As an interim measure, I acquired an extra long scrubbing brush (3.5 meter extending handle) and rubber sqeagee that you plug a hose in at the handle end and it squirts water at the working end.
3.5M Telescopic Wash Brush + Soap Dispenser + Squeegee+Solar, Trucks, Windows | eBay
At least that way I could keep the panels clean enough to get power while seeking a solution--and avoid guano slurry flowing onto the hardtop, down the clears, and onto the deck.
Next: monofilament. Now, you'd think that solar panel manufacturers would have thought through the problem of birds pooping on panels, and on the shading effect of various solutions, not for boaters but for their big users, places like commercial shopping centers. When I called the PV panel supplier (the Australian subsidiary of the Sunpower), the told me to contact a shopping center in Rosebud. He in turn didn't know and referred me to a pest control group Rentokil in Melbourne who told me the control problem was for aircon not panels, but they used netting to get effect.
Which took me right back to monofilament. Now, there's not a lot of data on the size of netting (square size) and the type of monofilament that one would need. Also, in Australia, netting is not transparent monofilament but black (you can get transparent if you search hard in the US). I thought about installing low (about 4 inches high) anchor points all around the panels which could also act as "spike" deterrents also used to deter birds atop street lamps etc. and rigging my own net. But that raised the issue of shade effects. So I called back Sunpower technical person in Sydney. Turns out they had no data, even on cable shading. But they did some calculations and tests and supplied the results:
Test parameters
thickness 50mm or 5 cm cable
spaced cables
tested 6 modules Max 3400 panels which are 1690(L) x 1046(W)
cables spaced about 0.5 meter apart
ie about 3 m cable per panel at
~ 3 cables per panel * width panel
height from panel: 1.5 to 0.8 meters
30 degree tilt, at bottom H=1.8 m, top H=~0.7-0.8 meters
Result: output reduced by 9-10% due to shading
reverse bypass is less because heat dissipation is much better on Maxeon 423 panels
voltage of module doesn't drop by much, can track within regulator
The problem is, as the tester told me, "This test is very different to use of very fine transparent monofilament line about 20cm apart in rows up and down a panel at about 6 inches H above flat not 30 deg angled panels." [he was not aware my panels are not angled but almost horizontally mounted.]
They also told me that transparent monofilament would have little effect on the panel's output as the shading is diffuse and minimal.
That said, I still had the mounting issue, the net fabrication to consider, and the fact that it would constantly need to be replaced due to UV degradation.
In desperation, I did some more calling around to bird control people and one of them referred me to a solution used in trellised agriculture and grapegrowers, namely, a PV-powered irrigator with a motion sensor which one might call a "hydroblaster."
Motion Activated Sprinkler - Bird Control Australia
I see their website is down for maintenance so here's a demo vid
With nothing to lose, I decided to rig one up. That entailed assembling it, mounting it on a PVC "pole" with a nylon base to the deck; and hooking it onto a long dedicated hose from the rockwall over the stern to the unit on the pole.
Et voila! it works. Not only does it deter seagulls by the agitated blast of water and spray, but when it does go off, it cleans the panels. There is a small loss of sunlight and power generation from droplet effect on the PV surface, but that doesn't last long. The movement sensor is adjustable out to 11 meters.
I haven't used the scrubber since it was installed about six months ago.
This system won't work for cruising vessels, or vessels on a pick; but for vessels moored most of the time at dock with available pressurized water, it works.
And I am back to enjoying watching the gulls hang out at their new landing pad, the end of the rockwall.
Unrelatedly, I was surprised by the lack of response to my posting on flare-like fire suppression systems last week.
https://www.trawlerforum.com/forums/s3/flare-like-fire-suppression-systems-69335.html
Photos of panels with poop; of the irrigator mounted on NW corner (least sun late afternoon); of clean panels.
