Solar Two - Fire Store Construction

On request from the orphanage, we build a fire stove for them. We got all the children in the orphange to help in carrying the bricks for the stove. We visted one of the villager's house to study how a fire stove is constructed. We came back using a double walled stove to prevent heat lost to the outside wall when fire is lit.

For the top, we constructed a mould and later put cement into it and allow them to dry before removing them. The hole size is determined by using their largest cooking pot.

We prepared the ground where the stove is to be placed and began brick laying.

We have a specialist who is good at mixing cement, sand and water in the quickest possible time.

Finally, we could see the shape of the fire stove. We place the pre-fabricated top onto the base of the fire stove and to complete the job, plaster the bricks to provide a good finishing touch.

Solar Two - Clean Water for an Orphanage

We installed a water filtration system for another orphanage in Cambodia. We used an ultra-membrane filter with pore size of 0.1 micron. It is able to remove bacteria and give clean water. It requires a minimum water presure of 2 bar to operate, hence we need to install an electric water pump before the filter so that it has enough pressure to operate the filter. A setback of this system is it requires regular back flushing in order to clean the filter to prolong the filter's life. Once the filter to clog up, it is time to replace a new filter. Suitable for making rainwater drinkable.

Solar Two - Rainwater Harvesting

We experimented and constructed a rainwater harvest system for the orphanage at Prey Veng.

Back in the laboratory, we experimented using the heat gun to seal plastic sheets together for making the rainwater collector. We also build a huge water bag to collect the 1 tonne of rainwater.

We brought all the materials to the orphanage and constructed the rainwater harvesting system. We used a monkey ramp to drive the iron picket into the ground. The plastic sheets were spreadout and tightly secured to the iron picket with steel wires.

The design need some fine tuning as we did not expect the rain in Cambodia to have very strong wind. One day when it was raining heavily, the strong wind blew and tore the plastic sheet which is used to collect the rainwater. We recommend them to build a proper roofing system instead of spreading a wide plastic sheet in the open. This approach will be able to withstand the strong wind when it rains.

Visited a Boarding School in Pontianak, Indonesia

In 2005, I visited a boarding school in Pontianak, Kalimantan, Indonesia. I followed a church group who were visiting the school. My role was to study if it is possible to help them make their well water drinkable using a simple water filter system. I brought water samples back for testing and found that the water was acidic. This requires an additional process of neutralisation to raise the pH level of the water to 7.0 before filtering.

Also notice that the water was greenish in the toilet and latter realise that it was due to the acidity in the water attacking the copper pipes.

I did not recommend to install a simple water filter system as they need to address the low pH first.

Solar One - Security Lighting

In April 2005, I designed and installed a security lighting system for an orphanage powered by a 500W photovoltaic system. The lamps are turn on nightly to ensure the ophanage is well lit and also prevents thieves from breaking into the orphange to steal things.

In order to keep the total power consumption low, high efficiency LED Lamps were used. Each lamp comprised of 3 Luxeon Star 3 watts LEDs driven by a constant current circuit at 400mA. The lamps were operating at 12Vdc. The lamps housing is IP44 comformance, meant for outdoor use. It is important in Cambodia because at night, there are alot of flies attracted to the light and they will try and enter the lamp unit, thus destroying the leds and its electronics.

We have to digg trenches to lay conduits and cables all over the orphanage compound for the installation of 24 lamps at different locations. Since we are covering long distances in the cable laying, sometimes more than 400 meters, we have to use a higher operating voltage other than 12Vdc. We operated at 24Vdc to overcome the losses from the voltage drop along the cables. Also, we used thick copper cables, 6mm diameter, to minimise voltage loss. Hence we have to connect 2 LED lamps in series so that it can operate at 24Vdc.

The controls for the solar charging is design around a charge controller from morning star. Simple to use and reliable. It has a build-in meter for charging and load current readings and also the battery voltage. This makes it convenient for testing and troubleshooting. The whole security lighting at the orphanage is divided into 4 zones and the switches are placed at the control box. In the morning, it is easy to switch off all the lamps because it is located at a central location. We used 4 lead acid batteries, each having a capacity of 120 AH. This provides enough stored solar charge for up to 3 days operation even on cloudy days where solar charging is minimum.

The mounting of the solar panels was a challenge. We finally were able to mount it on a pole using available resources such as dinning tables, stack up, from the orphanage.

The solar charging and discharging cycle is shown in the graph. When the sun rises, charging begins at around 7 am and peaks at 1 pm and begins to decline after 5 pm. At night at 7 pm, the lamps are switched on and the discharge cycle of the batteries begins. The terminal voltage of the battery never falls below 25 volts. Hence the system is balanced, i.e. day time charging is sufficient for the whole night operation.

Once completed, we switch on the system and it works as planned. The orphanage was litted by solar one!

Solar One - Low Cost Solar Oven

In 2005, I designed a solar oven to help the villagers in Prey Veng, Cambodia to reduce their dependency on fire woods for cooking. The design is base on a parabolic design using highly reflective aluminum foils to concentrate the sunlight to the cooking pot. The concentrated sunlight is able to produce temperature of above 150 degrees Celcius, thus able to boil water (100 degrees Celcius) in the pot and cook food. The cost of the solar oven is about USD60, still very high by Cambodian farmers' standards.

After completing the construction of solar ovens, we taught the village chiefs how to use the oven for cooking. It takes about 1 hour to cook rice. We have tried cooking a mixed vegetable rice using long beans, black fungus, dried prawns, peanuts and rice. The food taste good and simple to cook. The village chiefs were amaze that the solar oven works. They brough the solar oven home to try out cooking using the sun energy.

One year later, in 2006, the Cambodians were able to reduce the cost of the solar oven further to only USD20. They use materials readily available in Cambodia and also simplify the design.