Solar Concentrators

Problem Statement:
– Treated and purified water isn’t readily available in many developing parts of the world.
– Many societies have access to water but no method for treating it.
– If societies in developing countries had access to clean water, they could see a great reduction in disease.

Project Goals

Build a low-cost and simple solar concentrator that will be able to bring a pot of water to a boil and thereby purify it.

Project Effects

– We are beginning with a prototype based on the link above to test and find out what difficulties may arise before we settle on a design. However, if we find that design to be inneffective we will continue to consider other options.

Target Population

This project is intended for impoverished populations in Yemen.

Yemen has major issues with clean access to water. It is both the poorest and most water scarce country in the Arab World. In addition there are approximately 1000 Syrian refugees in the country with little access to food or shelter.

Water access is typically limited to a cistern or well and walked back to the home. World Health Organization statistics indicate that just 26% of the rural population has access to piped, clean water and 33% have access to improved sanitation. There are an estimated 13 deaths per 1000 children 1-59 months old due to diarrhea. Clean water access will certainly combat this.

The climate in Yemen ranges from dry/arid to alpine/highland. It is estimated that 37% of the population lives in the dry/arid region which can get as high as 120 degrees Fahrenheit. This makes walking to and from water sources brutal. However, we believe that in harvesting sunlight through the use of a solar concentrator we can use that resource to assist in water purification and prevent the use of potentially contaminated water sources particularly in rural regions.

Week 3 Update!

We have elected to go with a Schefler design for the solar concentrator and have decided to focus our efforts on building insulation for a pot that will be the focal point of the concentrated sunlight.

– It is our hope that our technology will make not just harvesting sunlight easier but also cooking and boiling/purifying water. We would like to design some type of insulating material for the heated pot. The design will be derived from the inherent cooking pots of the culture which we will be designing for. The insulating material we have been considering thus far is cob. Cob is a clay, sand, and straw hybrid building material; when compressed it forms into a cement like material.

Week 6 Update!

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Application of first batch of Cob to repair existing cob structure, solely for becoming familiar with the material’s structure when dry, and for adjusting sand:straw:clay ratio.


Cob close to a week later. Looks flaky but VERY hard (we were surprised, it was like cement; flakes were difficult to pry off)


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Week 8 Update!
We’ve purchased genuine wool as our insulating material. The reasoning being that in the middle of Yemen there wouldn’t be much else insulating matter that isn’t also flammable and difficult or dangerous to use in conjunction with cooking (fiberglass for example). The wool insulated cookware covered in cob could also be used as an artistic outlet where women (generally the ones who cook) could coat the cob in a plaster like material so that it has a smooth and uniform look which can be further artistically modified.

Week 9 Update!
Jacob has been hanging out with President Armstrong (no big deal right!) and so we have been just talking about where to get supplies and when/how we could carry this out

Week 10 Update!



making cob the cool way


wooling up the pot (we used a small one since it’s cheaper and a small scale prototype study is easier than coating a whole 5 gallon vessel and testing something that could realistically take all day to cool off)

Cooling Study:

Calibrating thermometers with boiling water

Measuring out 750mL mark

Measuring out the 750 mL mark


Taking ambient temperature


The setup without the lids


The pot is removable


Taking temperature (Jacob’s hand with thermometers visible in the pots)


Close-up of the prototype
Insulated pot with thermometer and data logging going on in the back.
Control pot being logged

Experimental Procedure of Heat Flow Study



·         Ambient temperature thermometer

·         Two boiling temperature thermometers

·         Volume-measuring container of known volume

·         Electric Stove

·         Two dry cotton towels to close gap caused by thermometer

·         Two cardboards to place pots for duration of cooling

·         Stopwatch

·         Two Experimental pots, and 3rd boiling pot.



Two thermometers were calibrated by placing them in boiling water near sea level to determine their accuracy. An ambient temperature reading was made twice throughout the run, one at the beginning, one at the end of the experiment. One 750 mL glass container measured out two times 750mL. 1.5 L total was set to boil in the 3rd boiling pot with a tight-fitting lid. Immediately after boiling was noticed, 750 mL was poured off into the 750 mL glass container, and two people working simultaneously, poured 750 mL into each pot. The water in the glass container was poured into the insulated pot, and remaining water in the boiling pot was poured into the uninsulated pot. At the time of pouring water, the timer was started. Thermometers were already laying in the pot, being supported by a dry towel placed on a sector of the lip of the pot. This was done to reduce heat loss through the cracks between the pot and lid cause by the protruding thermometer. Temperature readings were taken, recording timer value at moment of temperature reading. Sampling interval was first about a minute, and after 10 minutes, about every two to four minutes. The sampling interval frequency aimed to have higher resolution during the faster cooling period when the difference in water and ambient temperature was greatest.

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Thermal conductivity of insulated pot is bigger, likely due to improper estimation of material thickness.

Thanks for building and testing prototype. The conductivity of the insulated pot (I think) was smaller, as indicated by the smaller decay constant for the insulated pot. I think you just got resistivity mixed up with conductivity? – Pete

Past Correspondence:

Your project is no longer consistent with many things you say in your website. Please update it, provide a decision matrix and some information about Yemen. Cob is a good building material, but it is not a good insulator. You may want to look for other options. At present, this website would earn a “C”.
The only readily available, and not easily flammable, option for insulation is wool. Therefore we haven’t had a real decision matrix since we can wrap the pot in wool and coat this in either cob or plaster or clay. Not many other options (fiberglass is dangerous, hard to come by; wood flakes/chips are highly flammable). The strength of cob, which we have examined since we thought of our design makes us think cob would be our best bet.

Intermediate Fidelity Prototype? At present, this website would earn a “C-“
There is no prototype yet since we need to get our hands on raw wool (with a woven blanket as a late second option) but the making of good cob can be considered one as it is essential to our overall design.

We are the group from University 392 intending build a solar concentrator. It is our goal to begin with a rudimentary fresnel design and work our way up through a trial and error method. Our inspiration came from this webpage