Tie Me Solar Down, Mon
I don’t watch much TV, beyond the network evening news. I was in the kitchen eating when my ears perked up about something solar on 60 Minutes. Then I heard Rocky Mountain Institute mentioned. I had to watch.
You’ll recall that a Cat 5 hurricane clobbered the Bahamas and just smashed the Dickens out of parts of it. Traditionally, power in the Bahamas comes from a Diesel plant on every island. Fuel deliveries are ever a logistical challenge. I’ve not personally seen that in the Bahamas, but I did see it in the Caymans when I was a computer tech back in the last century. The power made by the Diesel plant was fairly dependable, but not really “clean” the way computers like it…hence my island visit.
60 Minutes didn’t talk much about the Diesel generator, except that it was over yonder and most of the users were here, 20 miles away. Not a power pole was left standing in between. I am betting the big engines ran just fine. The problem was how to get power from yonder to here. It would require new poles and lines, like folks didn’t have enough other stuff to worry about.
Then somebody came up with the idea of microgrids. Put the power source close to the users! You can still tie microgrids together to make a big grid, too. The plan is to put a few acres of solar here and a few more over there until everybody has some.
Enter the guys from Rocky Mountain Institute. Google them when you finish here and download some papers I am going to tell you about.
You say they are going to put up solar panels. Didn’t nearly every house on the island just get flattened? How are solar panels going to stand up to 180 mph winds?
That’s where the Rocky Mountain Institute boys come in. A while back, they studied solar panel failures after storms. For the most part, the failures were either caused by flying objects or the panels themselves became the flying objects, causing more havoc. They concluded that it would be a good idea to mount your panels well enough that they stay put and do not become flying objects. They are taking it a step further on the island system, mounting them very low and skirting the to keep the wind from getting under and lifting them.
Duh. Well that may seem obvious, but nobody had really analyzed installations and failures to see what that meant. Turns out it isn’t that complicated to tie things down and a lot of common practices need to be changed.
You can find the Rocky Mountain Institute website and download the free pdf report for all the details, but I’ll hit the highlights. Oh, I should warn you…there will be graphic photos of smashed and twisted solar panels. It’ll break your heart.
So many times you see one clamp between the edges of two panels and a bolt going down between them to the frame. Don’t do that! Use separate clamps for each module.
Don’t hold things down with screws. Use bolts.
Make sure your supports are firmly in the ground.
That’s just hitting the highlights, but it makes sense. It really doesn’t take much to hold the panels down under normal conditions. When the hurricane comes, the challenge is simple, though: keep the panels in place.
To avoid wasting land for mounting solar panels, a lot of microgrids try to use rooftops. Keeping a rooftop in place can be a challenge and a necessary part of installing solar. Many of the same techniques apply to rooftop solar, but the challenge has to include keeping the roof in place. Keep the roof in place and chances are you can still use the building after the storm! RMI just finished a paper on rooftop system survival, so be sure to download that one, too.
To emphasize their point as to the value of microgrids, they used Puerto Rico as an example. After the total destruction of their grid, solar microgrids were installed at schools. The recent earthquakes knocked the grid down, again, but the schools and other buildings so equipped had power. Hurray for solar!
Another point made in the story was that building a solar power plant is now pretty much on par with building any other source. Batteries have come way down in the last few years, though we individual users would surely like to see some more breakthroughs.
I look at my own system and really, really hope we don’t get a hurricane. We are overdue, here, near Pensacola. My recycled solar shingles are only rated at 60 mph. That’s just tropical storm level. There was an optional clip that is no longer available, but I could replicate it, sort of. The problem is there are hundreds of panels and not all of them are readily accessible.
Most of my conventional panels are on temporary mounts for some of the cockeyed tests I am running. I know they could be better and they could be easily bolstered or just taken down in a few hours. The entire mounting structure is wood. Wood has some give in a stressful situation, but it is all very high and there are no bolts. The framework was put together with a nailgun to get started and long deck screws were added to strengthen the bond. Metal straps would be better and maybe they will get added.
After reading the RMI reports, I am a bit nervous about my own installation. Upgrades are not out of the question, but it is quite obvious that it would have been a whole lot easier to put them in place during construction and they really would not have cost a lot extra.
How would you rate the survivability of your system?