Solar Village

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16 Home Power #71 June / July 1999

ambodia is small tropicalSoutheast Asian country of about10 million people. The country is

largely rural, with the majority of the

population living in the provinces. Dueto the rural population and lack of

government funds for electrification,approximately 85 percent of the country

is not electrified.

The parts of the country that do have electricity haveonly intermittent service. Electric power service forhouseholds generally consists of small generators,private power vendors who own large generators andsell power to houses, and battery charging stations forsmall 12 volt systems.

In 1997, my wife was offered a job with the AsiaFoundation to run the Womens Economic and LegalRights Program in Phnom Penh. I was able to take ayear off from my energy efficiency job in Washington,DC, and went to Cambodia with the goal of starting asmall PV business in Phnom Penh.

Starting a PV Business

Since we expected to stay for just one year, I began bytrying to find a partner who could continue the businessafter we left. After a long search, I found Mr. Ford Thai,a local businessman with extensive businessexperience and the ability to speak six regionallanguages as well as English and French. Ford is alocal legend. Hes a Khmer (Cambodian) of Chinesedescent who drives an American speedboat on theMekong and takes his pet monkeys with him whileinstalling PV systems. He is a colorful and delightfulman, and it was a pleasure to work with him from thevery beginning.

Our first task was to determine which solar productswould succeed in Cambodia. We chose small PVlighting kits for use in the millions of countryside homeswithout electricity. We found that it was necessary touse Asian components. They were our only practicalchoice, given the cost of importing from the U.S. orEurope, and the price sensitivity of the Cambodianmarket.

The kits consisted of a solar module, a chargecontroller, a 12 volt light, and a battery. During our firstfew months, we installed a solar electric computer

Peter Banwell 1999 Peter Banwell

Samaki village fishermens houses with small PV modules on poles.

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CCC


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system in a rural office and a lighting system for a ruralhealth clinic. As we were growing, we registered ourbusiness with the government under the name KhmerSolar.

Government Connection

In pursuit of potential projects, I met with the Director ofthe Energy Department for the Cambodian government,Dr. Sat Samy. He was in the process of specifying andselecting solar equipment for a village solar project, andbecame interested in our solar lighting kits. After sometests of the kit at his house, many discussions, andcomparison of our systems with others, we wereawarded the contract to install 38 PV lighting systems.

The ProjectThe project plan was to bring solar lighting kits toSamaki, a small fishing and rice farming village near theKampong Som and the Gulf of Thailand. The village

was approximately 5 km (3 miles) from the nearestlarge town. The houses in the village were elevated onstilts, had one to two rooms, and were built in traditionalCambodian style, with bamboo framing supporting apalm frond roof.

As their only source of lighting, villagers were usingsmall kerosene wick lamps, which were dim, smoky,and dangerous. The villagers did not own batteriessince they were unable to transport them back and forthto a larger town for recharging. Solar electric lightingkits were the first source of electricity in these homes.

The kits were designed to provide one to three hours oflight per night, depending on the season.

Selecting & Testing the PVs

We looked north to China to supply the modules for thelighting kits. China has a thriving domestic market forPV and it was our closest economical choice for smallmodules. Through a regional renewables advocacygroup, we found Yunnan Semiconductor, a Chinesemanufacturer offering good quality modules. Theirfeatures include 36 single crystal cells, aluminumframes, ETA backing, imported low iron glass, and a 20year warranty.

Our tests revealed that the modules were not producingtheir rated current and they were also not properlymarked with current and voltage data on the back. Wesuspected that we had been shipped the wrong size ofmodules. Upon further discussions with the factory, welearned that the Chinese have a rather odd system forclassifying modules. They have three 12 watt modules:12A, B, and C, with C having the lowest output. Wewere sent 12B modules, which have the engineeringspecifications of 11 watt modules. Although the Chinesenever agreed with our logic, or we with theirs, in the endwe were issued a refund equal to one watt per module.

Choosing Charge ControllersThe lighting kit was to have one small charge controllerto protect the battery from overcharge andoverdischarge. We tested two types: the Morningstar

6.0 and the Steca Solsum 5.6. Many of the featureswere similar. Both had protection from reverse polarity,were suitable for tropical environments, had two yearwarranties (the Steca warranty was extended for thisproject), met quality standards set by the World Bankfor PV projects, had low voltage disconnect, and hadPWM charging.

After all of these features were examined and weighed,we found that the Steca had one significant technicaladvantage over the Morningstar: an LED that changescolor with battery voltage, then flashes a cutoff warningat low voltage. In contrast, the Morningstar will

disconnect loads without warning. With the smallsystems we were planning to install, an unexpectedload cutoff could have left villagers in the dark for over aweek while the battery recharged from a small PVpanel. In the end, this feature and the much lower pricefor the Steca convinced the Energy Department. Sincemaking the selection, we have found that Stecascustomer service and distributor support is excellent.

Selecting BatteriesSince deep cycle batteries were unavailable inCambodia, our choice was to either import deep cyclebatteries at $200 each or use standard car batteries at

Installing a solar panel on a pole.


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$23. The economics strongly favored using carbatteries. We recommended a 32 AH car battery, whichwe expect to last 2-4 years, depending onmaintenance.

Car batteries are widely used in Cambodia for ruralelectrification in homes such as the ones in Samakivillage. Tens of thousands of people in the countrysidebring their 50-100 AH batteries in to a charging stationonce a week, and have learned that fully dischargingthe battery comes at the cost of battery life. With thisinfrastructure in place in the larger towns near thevillage, we decided that car batteries were a reasonablechoice. Automotive batteries are not ideal, but they arecheap, and with proper maintenance they can last along time. The village chief is responsible for batterymaintenance, and each homeowner was given a smallbottle of battery water to keep near their system.

Using the Steca

The charge controller is an essential element inmaintaining the health of the car batteries. For the

charge controller to be effective, we needed to teach

the homeowners what the LED indicator lights meant.We did this in two ways. First we had a training sessionfor all homeowners, and then we distributed bookletswritten in Khmer explaining what the color changesmeant. The goal here was to get the homeownersaccustomed to reading their charge controller, andkeeping their battery as full as possible. We designedthe systems for a typical daily battery depth ofdischarge of ten percent.

The settings on the charge controller are as follows:green is 12.7 V, yellow is 12.3 V, red is 11.8 V, flashingoccurs below 11.8 V, and cutoff happens at 11.1 V.Reconnect voltage is 12.6 V, and the charge controllershave temperature sensors to compensate for hightemperatures.

Testing and Selecting LightsThe homes in the village were small, and the project

goal was to bring light to just one of the small rooms.There were several l ights available to us forcomparison: a reasonable quality import at a goodprice, a moderate quality, low price fixture made locally,and a screw-based compact fluorescent from China.

The Energy Department was not interested in the screwbased fluorescent, since the villagers could not easilyand economically replace it. After comparing the lights,they chose the locally made fixture, a 10 watt straighttube with a reflective backing. While we encouragedthem to step up in quality to an imported fixture, we

recognized that locally made fixtures were used all overCambodia and would be very easy to repair or replace.

The Installation

On the day before the installation, we assembled in thegarage under the Khmer Solar office. The crew ofseven was made up of Khmer Solar technicians andemployees from the Energy Department. The crew hada good mix of experience. Some of us knew the solarside well, and others were electricians or electrial

Khmer Solar technician,Toch Sovanna, prepares charge

controllers. Ford Thai, president of Khmer Solar, watches.

STECA

11 watt PV panelfrom China

Stecacharge controller

with LVD

Car battery32 amp-hours

at 12 volts

10 watt fluorescent light

from Cambodia

Wall-mountedswitch

Samaki Village System


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19Home Power #71 June / July 1999

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engineers who were highly skilledwith tools and wiring. The importeditems had made it through customs,and we had all of our equipment forthe project. On the bare floor we laidout all the modules, chargecontrollers, mounting racks, sub-boards, lights, wires, screws, bolts,and tools.

At sunrise the next day we leftPhnom Penh by car and truck,winding our way out of the cityagainst the incoming swarm ofmotorcycle commuters. After a fewhours on a good road, we turnedonto a dirt track that ran betweenthe rice fields. Fishermen worked

their nets in the clay-lined canalsnext to the road. Soon the groupcrossed an old metal bridge leadingto our destinationSamaki village.

Samaki is a small rice farming and fishing village on thePrek Kampong Smach River, near the coast. It has apopulation of approximately 200. We were led to thevillage chief, who was in a large courtyard area underhis elevated home. This area served as our stagingground where we set up all of our equipment andworked out of the sun and rain.

When we started working on the installation, the sevenof us broke up into teams of two or three, each with ourown equipment and a full set of tools. The village hadfishermens houses near the river, and rice farmershouses far off in the rice fields. Our job was to installsystems in all of the houses, so we expected lots ofwalking.

Wiring & Installing the ModulesAlthough I can list a number of quality features of theYunnan modules, the junction box is not on that list.The box was a tiny thing, leaving no room for any typeof fasteners. To make the electrical connection, we had

to solder the wires directly to the plus and minus tabs inthe junction boxes. Although soldering is t imeconsuming, it did give us a high quality connection.

Outside of the cities, Cambodians commonly usetraditional palm fronds for their roofs. The fronds arereplaced every couple of years, so it was necessary toinstall the modules on poles instead of roof mountingthem. We used wooden poles standing next tobuthigher thanthe roof, facing south at an eleven degreeangle.

By the end of the first day, we had installed most of the

poles, and two complete systems. After finishing our

work, we drove to the beach, walked through the palms,and swam under the stars. The only light was from themoon, which slowly rose over the gulf of Thailand. Theother beach inhabitants were large fruit bats that floatedgracefully past us through the tropical night.

Installing Charge ControllersWhen we started early the next morning, we began with

the charge controllers, batteries, and lights. Weprepared the charge controllers by mounting them tosmall wooden sub-boards, which were spray paintedeither bright orange or dramatic silver. We used largescrews to affix them to the wooden framing in thehouse, at eye level, where homeowners could easilysee the LED voltage indicator lights.

Then we ran into a problem. The Steca chargecontroller works best with single strand wire since its

junction holes are close together. But because we wereusing multi-strand wire, single wires easily strayed fromtheir narrow space and shorted the circuit, causing

Ford Thai and Ly Che Chen on their way to the next two houses.

PV Lighting Systems

Component Cost Percent

11 watt modules $91 45.5%

Steca Solsum 5.6 $35 17.5%

Shipping, insurance, customs $35 17.5%

32 AH car battery $23 11.5%

10 watt fluorescent light $8 4.0%

Iron mounting rack $5 2.5%

Wiring, screws, etc. $3 1.5%

Total $200


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sparks, blown fuses, and furrowed brows. The solutionwas to prepare the wires beforehand at the chiefshouse, before they were installed in the houses. Wetrimmed the lose wires and treated them with solder.The solder bonded the wires into a single strand andthe wires then slid into the connection holes easily.

Lights in the Darkness

We spent our third day finishing up the wiring on thecharge controllers and lights, and our work proceededwithout difficulties. It took three days to install the 38systems. As we packed our equipment late on the lastevening, a powerful wind began to blowmonsoonseason was beginning. We were on a fishing pier ashort distance from town, where we stayed for thesunset. As the tropical night quickly fell around us, theindividual homes began to light up one by one, breakingout of the darkness for the first time.

We went back to visit the project several months afterwe completed the installation, arriving in the evening.As we walked through the village, we could see peoplein their houses sitting in small circles under their lights.They were reading, eating their evening meals, andtalking. People reported that their systems wereworking very well, and although we dont have hard

numbers to report yet, it appeared that they had learnedto live within the energy budget of the small systems.

When our visit was over, we drove out and crossedseveral miles of rice fields before reaching the mainroad. Looking back before we turned towards Phnom

Penh, we could see Samaki village, a small cluster oflights shining brightly against the dark backdrop of themountains.

Access

Author: Peter Banwell, 7221 Cedar Avenue, TakomaPark, MD 20912 301-587-2375 [email protected]

Ford Thai, Khmer Solar, PO Box 1561, Phnom Penh,Cambodia 011 855 15 830 038Fax: 011-855-23-362-077 [email protected]/khmersolar

Controller manufacturer: Steca, Mammostrasse 1, D-

87700 Memmingen, Germany 0049-8331-8558-0Fax: 0049-8331-8558-11 [email protected]

PV manufacturer: Yunnan Semiconductor DeviceFactory, Jian She Lu 24, 650033 Kunming, PeoplesRepublic of China 011 86 (871) 5362240Fax: 011 86 (871) 5337279

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