I’ve become very interested in projects that normal, everyday people can do that will harness the free power of the sun. This ‘solar flower’ is intriguing, and it can be built very cheaply, or even for no cost if you visit a scrap heap and rummage through your own ‘junk’. What is it used for? “Basically, generating heat. With that heat you can then run external applications such as generating electricity, smokeless cooking, heating and purifying water, making charcoal, anything that heat can be used for.”

Visit www.solarflower.org for more information.

 

What is it?

A solar energy collector you can make easily using scrap materials.

What’s it for?

Basically, generating heat. With that heat you can then run external applications such as generating electricity, smokeless cooking, heating and purifying water, making charcoal, anything that heat can be used for.

How much does it cost?

Depends. All the materials are things you can find in a corner store or scrap heap, so it could potentially cost anywhere between nothing and, let’s say about €$£50 per device.

How much power does it produce, and how efficient is it?

One square meter of full sunlight is about one thousand Watts of power, which is the collector size for which the SolarFlower is designed (although it can probably drive something twice as large). Depending on the materials used, you can assume at least 50% thermal efficiency overall (probably higher), so that would give you 500 Watts in full sunlight. This is enough to heat 50 litres of water to 100 C in a little over 8.5 hours.

What principle do you use to track the sun non-electrically?

It’s a little complicated to express in text, I’m working on some animations at the moment which will make it clearer.

Basically there are two collector mirrors, one big one that concentrates all the energy you’re going to use to power your applications, and a smaller one attached to it which drives the tracker. When the main collector is pointing directly at the sun the focus point of the secondary collector is sitting just off the edge of a little boiler filled with a small amount of ethanol. As the sun moves off by about a degree that hot spot shifts onto the boiler, which in a minute or two starts the ethanol boiling, the vapor exits into a chamber (metal tin) attached to the boiler, and forces out some of the liquid ethanol in it. That liquid goes through a pipe and pours into the waterwheel assembly, turning it, which turns the gearing, which turns the two collectors into the sun, the hot spot shifts off the boiler, the boiling stops, the vapor in the tin starts to collapse and the resulting vacuum sucks ethanol from a reservoir below the waterwheel and refills the whole system.
It all sits there until the sun moves off again.
The small collector has about a two hour range, so if the sun goes behind a cloud or something the system can catch up to it.

What license / patent / protection is on the design?

None. This is an open source hardware project, and as such is not owned, or able to be owned by any one person or company.
Since the designs have now been published they are unable to be patented by anyone, including the original designer.
At some point the project may take on a Creative Commons or similar license, but it will be one which allows any form of use, including commercial. (In fact you are encouraged to make and sell these things, royalty free).
The only thing you are not permitted to do is stop anyone else making and using them in any way.