Solar Concentrator with Inflatable Mirrors

We are reaching an important milestone in the Testfield: the high-precision membrane mirror that we have been working on for the last two years, is standing. A team within the technology group has designed and built a prototype solar concentrator by innovating and developing the inflatable membrane mirror technology first introduced by father and son Hans and Jürgen Kleinwächter several decades ago. The present advances are the result of a dedicated team within Tamera working in cooperation with Jürgen Kleinwächter, SunOrbit (Germany) and supporters in India and Australia.

Our prototype mirror uses 0.1mm thick reflective polymer films inflated with air pressure, over a lightweight aluminium frame, achieving high optical precision cheaply and with very low embodied energy. It has an effective optical aperture of 4m2, concentration of over 1000 times, reaching over 1000 degrees Celsius, and has applications ranging from round-the-clock cooking with storage, through ceramics, metalwork and lime burning for waterproof clay buildings, to photo-catalytic fuel production from water and CO2. Future concentrators will undoubtedly take the technology further.

Many challenges in the components and sub-systems have been overcome over the last two years. Now we will start to see how the system really functions as a whole. We have progressed from unstable wooden experiments to a simple, lightweight aluminium framework, developed a deflectometric mirror analysis technique using computational photography, built a tool to weld flouropolymers together (basically welding Teflon to Teflon), designed and fabricated a dual-axis tracking construction, and invented a robust technique to evenly tension membrane films. We are looking forward to testing and tuning the complete system. System tests will start now, as we continue to complete the details.

Quoted from: High-precision Membrane Mirror Research in the SolarVillage Testfield of Tamera, August 2016.

Previously: The bright future of solar powered factories.

Gravity-Powered Solar Tracker

gravity powered solar tracker

The SunSaluter is an ultra low-cost, passive, single-axis solar panel rotator (called a tracker) designed for the developing world. Using only the power of gravity and water, the SunSaluter enables a solar panel to follow the sun throughout the day, boosting efficiency by 30% and producing four liters of clean drinking water.

It is 30 times less expensive than conventional motorized solar panel rotators (which use complex electronics), much more reliable, and consumes no electricity itself. With improved efficiency, fewer solar panels are needed, and the overall cost per watt of solar energy is reduced.

The SunSaluter features an adjustable design which allows it to integrate with any solar panel – no special tools needed. The solar panels are mounted on the rotating frame, a weight is suspended from one end, and a special waterclock is suspended from the other. As the water empties and the container gets lighter, the panel slowly rotates. The user can set the rate at which the waterclock empties, which controls the SunSaluter’s rate of rotation.

The SunSaluter also contains a water purifier so that each day it produces four liters of clean drinking water. By combining energy and water collection into one simple device, the SunSaluter improves consistent usage of the purifier, which is the Achilles heel of clean water programs. SunSaluters are available for purchase anywhere in the world as a DIY-kit, or in India as prefabricated systems.

More information: SunSaluter. Via Makeshift, who made a video about the technology.

Why Solar Roadways are a Silly Idea

“There’s currently a virtually endless supply of places you could install solar panels that DON’T have cars driving over them.” Read more at Equities and check out the comments at Slashdot.

Solar Powered Grain Mill

solar milling

“Graining cereal crops is a basic, century old business and it will continue to be as important as ever before for centuries to come. Before the age of oil grain milling was entirely based on renewable energy. It was either done by wind energy, hydropower, animals or manpower. For the last century the traditional grain milling has been mainly replaced by electricity and fuel driven milling.”

“The Solar PV Grain Mill works to the same principle like any conventional, electrically driven mill. The mill has a very efficient 3-phase AC motor which is directly coupled to the graining system. The main invention of the system is, and that makes it unique among PV systems, that it is a “direct drive system” without the need of batteries. The Solar PV generator converts solar radiation into electricity, and the generated electricity is directly feeding the motor drive. There are no additional conversion losses, such as energy storage losses in batteries, battery maintenance or replacement costs, which are a common problem in conventional Solar PV off-grid systems.”

Read More: Solar Milling. Via Engineering for Change.

I would like to add that the direct drive system also eliminates the high energy use caused by the production of the batteries, which can make solar PV off-grid systems everything but sustainable. Therefore, storing work instead of energy — the solar mill only operates when the sun shines — is a very interesting strategy in sunny regions.

Related:

The Passive Solar Bird Bath

The passive solar bird bath provides some unfrozen water in the winter for the birds to drink. Its a nice simple design that is easy to build. The sun shines through the glazed panel on the south side of the pedistal and warms a solar absorber which heats the bird bath from below during the day. Jim got the idea from passive solar horse watering troughs. Find the building plans at BuildItSolar.

A Passively Cooled House in the Tropics

passive house tropics

Build-It-Solar blog writes:

Kotaro Nishiki built a passively cooled home in Leyte Philippines at 11 degs north latitude that incorporates a number of unique cooling features that allow the home to be cooled passively and without electricity…

In this area, most homes are constructed of concrete, and the concrete structures tend to absorb solar heat during the daytime, and then retain that heat through the night making the homes uncomfortable.

Kotaro’s design is centered on eliminating these daytime solar gains. He keeps the whole house shaded using these techniques:

  • The south facing single slope roof has on overhang on the south that keeps the south wall in shade most of the day.
  • The north side of the house is shaded by an roof extension sloped down to the north that shades the north side of the house most of the day.
  • The roof is double layered with airflow between the well spaced layers.  This greatly reduces solar heat gain through the roof.
  • The east and west walls of the house are double wall construction with a couple feet between the walls.  The shading that the outer wall offers plus airflow between the double walls keep the wall temperatures low.
  • In addition, he has worked out ways to take advantage of the night
    temperature drop and to use thermal mass on the basement to provide some
    cooling.

More: A unique, passively cooled home in the Tropics (Build-It-Solar), Passive Solar House in Tropical Areas (Kotaro Nishiki). Build-It-Solar has more examples of passively cooled houses.