Saturday, September 10, 2011

Email re: Solar Water Bottle Bulb

solar light bulbThe light of life..mp4

Email rec'd 10 Sept. 2011 and my response:

Catherine Todd
Sat, Sep 10, 2011 at 10:30 PM

Dear Melody,

Thank you for the link with videos and instructions (pasted below)!

I had pieced together instructions from all over the web, but these are a nice list with two good videos. But I see some discrepancies and some questions that still remain. I'm sick right now on medication, so I'm not very well organized below, but here are my thoughts. Let me know what you find out.

This idea is so great that I will pay someone to draw up real instructions in Spanish and English if we can get a real, working model. Then we need to start doing real tests.

I'm finding a few problems with the simplistic instructions found on the web.

I'm going to see what my architect & engineer in Guatemala thinks about this when I get back next week.

1. Bottle cap may fail due to UV rays. Instructions say "use film dispenser cap" to protect the cap. No one has "film dispenser caps" anymore since we are all digital.

2. I've seen instructions for coating the bottle cap with caulk to protect it from the sun's rays, or people have just capped it with a regular bottle cap, as shown in the video. Who knows what might happen?

3. I also wonder about: "The solar bulb is expected to last up to two years before it needs changing."

What part(s) will need changing - i.e. fail - within two years? I'll do a test and start the process.

4. I've seen the square piece of tin roofing material caulked on the underside and then riveted down on all four corners, with the edges of the plate, all rivets and the plastic bottle cap covered with caulk. Or just caulked on the edges. Seems like rivets are a better way to go.

5. I've seen "clean water" and "purified water" instructed to be used, and "don't use tap water or mold will grow". Since you add bleach, I'm not sure what if any the difference is.

I spoke to an engineer in the states about this solar bottle bulb idea and he pointed out something important:

6. It is only the caulk that keeps the bottle in place.

He felt that there was a good possibility the caulk could fail within one to two years, and "probably during the rainy season." He cautioned me against cutting holes in people's roofs without "seeing how this plays out first."

7. Perhaps we can add a cage of some kind to hold the bottle so it wouldn't depend solely on caulk for keeping it in place.

8. I'm also going to bring some of the best outdoor caulk I can find when I return to Guatemala. There's no guarantee that high-quality caulk will be available when I get there, or at what location or price.

9. Hole in plate: Check the video on my website that shows the actual construction of the metal plate, that has small tabs cut on the inside of the circle and are bent into place.

That is better than the simple instructions below that say

"Step 2. Make a hole in the 1’x1’ roof sheet material, just the same size of the bottle’s circumference..."

10. On the link you found and on my eco-blog there is a video of an engineer from Brazil who installed these solar water bottle bulbs in his workshop three years ago, and started this idea. He used film dispensers over his bottle caps. I don't know how they've held up. I am going to try and contact him if I can find any kind of contact information.

11. Water:

Step 1. Fill the 1.5 liter clear soda bottle with purified water then add 3 tablespoons of liquid bleach and tightly seal the cap. Do not use tap water because this will allow the growth of moss.

I don't think it matters what kind of water is used, as long as it's clean, if it has bleach in it which will prevent moss. If you are using "purified water" then you aren't recycling used bottles, as you might as well just buy the liters or refill them from a larger container.

11.b. Cap: I also don't know what "tightly seal the cap" means. If you don't caulk it, I wonder how much will dissipate? Seems like a lot.

12. Bleach: I think the Brazilian engineer used two capfuls of bleach but I've also read using 1 capful. Your link says "three tablespoons." It should be just enough bleach to keep mold from growing in the water. I don't know how much that really is, so this will need to be tested.

13. Indoor Tubing:

A scientist friend of mine has suggested running two pieces of plastic tubing from the bottle down the inside of a wall and putting a reflector behind it. He said leave the tubing movable "for close work" and the reflector would really help brighten the house. So I think there has got to be something to this.

My architecture blog with everything I could find about the solar bottle bulb:

Here's the instructions from the link you found below.

Thanks for writing and please let's keep in touch! I'm really excited about this project and want to do it right. CT

How to make your own Solar Bottle Light Bulb?

The materials are the following: 1.5 liter soda bottle, 1’x1’ roof sheet material, purified water, camera film dispenser, chlorine and a rubber sealant.


Step 1. Fill the 1.5 liter clear soda bottle with purified water then add 3 tablespoons of liquid bleach and tightly seal the cap. Do not use tap water because this will allow the growth of moss.

Step 2. Make a hole in the 1’x1’ roof sheet material, just the same size of the bottle’s circumference and insert the bottom part of the bottle leaving it exposed under the sunlight.

Step 3. Next, make another hole on the roof of the house (same as the bottle’s circumference) where you want to put the solar bulb and firmly fix the device.

Step 4. Seal the roof with a sealant to prevent raindrops from getting inside the house. It will produce a light when the water inside the bottle bulb refracts and scatters the light inside the house.

The solar bulb is expected to last up to two years before it needs changing.

See two videos on the website, includes "Solar Bottle Bulb from"

The Brazilian video is also on YouTube:

Related Search Terms: solar bottle light, solar bottle, solar bottle bulb materials, Solar bottle bulbs, solar bottle light bulb, solar light bulb, bottle bulb, solar bottle bulb procedure
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