Solar Cells Info

Source: EV World Blog, July 19, 2009
http://evworld.com/blogs/index.cfm?authorid=12&blogid=780&archive=1

Dr. Richard Komp sent the following report from Pakistan today. Since he’s been a guest in my house and I’ve spent a fair amount of time with him when he was here in Omaha, I thought I’d share his email with you. You can watch the multi-part video I shot of one of his presentations at the King Magnet School on YouTube.

The monsoons have arrived. For days now it had been hot and muggy (Like southern Indiana in the summer) but on Friday the rains started. Just sprinkles at first but Friday night a big storm came in with lots of thunder and lightning and torrential rain. On Saturday, Faizan’s father Irfan and I went out looking for the thin, tin plated copper ribbon we use to solder the solar cells together to make the PV modules we are building. There was flooding at some of the intersections but it wasn’t too bad getting around when we started out.

We went to the Saddar market section of Karachi to check out the rows and rows of electronic market stalls, which sell everything you can imagine in the way of electronic parts – except tin plated copper ribbon, we found out. We splashed through flooded streets in the continuing rain going from stall to stall following directions as to where we might find the ribbon, but never did, there in the electronics area.

However, one of the stalls was selling PV modules and systems so we stopped and talked with them to see just what the photovoltaic market is like in Pakistan. It turns out that there already is a PV module manufacturer in Pakistan making rather good modules using a regular laminating machine and the Certified method of assembly with tempered glass (from Turkey), EVA (ethylene vinyl acetate) and a Tedlar backing. The 80 watt module we examined is selling for about $320 or $4 per watt. Most of the rest of his stock was a collection of Chinese made modules that he was buying for around $2.50 per watt. Just since I came, (although I am pretty sure my presence had nothing to do with it) the Pakistani government has put a 25% tariff on the importation of finished PV modules, but has left duty-free the materials needed to manufacture the modules. This will be good for the new Sooraj Solar Company being organized by the people I am teaching, since they are in the process of purchasing an entire pallet of 10,000 Evergreen Solar cells to be air freighted here in the next couple of weeks. The off-spec Evergreen Solar cells are now less than 75 cents per watt in that quantity, and all the other parts (like the glass and transparent vinyl table cloth backing material) are cheaper here than in the US; so the cottage industry can compete with the Chinese imports and still make a decent income. The Solar market proprietor is very interested in carrying the new Soonezla brand of PV modules.

After the nice long discussion in the solar market with glasses of tea (I chose 7-Up after wondering how dirty the cups were), I suggested that we go to the jewelry artisan part of the Saddar, where people work all the time with thin gold, silver and copper sheets. Going around the stalls, Irfan spotted a silversmith he knew (who waded knee deep through the creek that the street had become, to come over and talk with us) and we discussed getting the ribbon made. He said that there would be no problem in making them from copper (although it might not be tin plated) and we settled on the dimensions: 2.5mm wide and 125 to 150 microns thick. In a few days we might have ribbon enough to continue making PV modules. We have already finished ten of the 60 watt ones and one 30 watt module from broken cells cut in half, and are making cell phone chargers while we wait for the ribbon to continue the production of the big modules. On Tuesday the 21st, we begin installing the finished modules and will probably do three installations by the time we finish the course on Friday the 24th. Irfan told me that there is a waiting list of people who have already spoken for 60 modules, so the cottage industry is well under way. However, we are still working on the problem of how to get larger quantities of the liquid silicon encapsulant we use instead of the EVA and the big laminating machine.

The people attending the course are mostly unemployed and two are refugees from the Swat Valley. I am not sure yet how many will be working as part of the new Sooraj Solar company and how many intend to work on their own, but their excitement is contagious as they work on learning these new techniques. Some of the people, including the Swat Valley refugees, have gotten very good at cutting the polycrystalline PV cells and others are having problems; but I have discovered that seems to be normal with these groups. It takes a certain kind of feel to cut crystals properly. We are using the latest techniques my friends like Marilu and Marco Antonio in Nicaragua have developed after their years of doing this work so the training is going well and the modules are looking ver professional. Of course, all of the modules are performing up to or better than specs and should last at least the guaranteed 25 years.

During the visit to the market, Irfan took me to a clothing shop he patronizes and decided to buy me some clothes appropriate for the climate of south Pakistan. We got a short sleeve shirt, a long sleeve dress shirt and two pair of nice lightweight, dress cotton slacks. I now have a size 42 waist! (There is nothing like a good tailor to make you face reality). The entire bill came to 958 Rupees; that is about $12 in total. I already have my emergency tie in my good jacket pocket so I passed on the 50 cent ties, although they looked pretty elegant.

The rain continued and when we drove back to the Alternative Energy Development Bureau (AEDB) guesthouse where I am staying, the streets had become rivers; except the newest streets where the city had put in large, well designed storm drains. Later in the evening, we were supposed to go to another wedding (this is the wedding season just before the month of Ramadan) so Irfan said he would pick me up around 9:30. In the afternoon and early evening, the storm intensified with strong winds lashing the rain against my windows and all the electricity went out all over town, as did the phones (cell phones included) and the Internet. Fiazan’s whole family showed up at the AEDB guesthouse in their car about 10:20 and said we were going to try to get to the wedding, which was only a few blocks away. Well we tried. The major streets looked like the creek behind Lynida’s house in Woodstock NY, waterfalls and all. Some streets were passable but there were lots of stalled cars blocking them and confusion at all the intersections. We finally gave up and got the car turned around to take me back. The street I am staying on is a nice boulevard with big trees in the middle. Many of these trees are now lying across the west lanes so we had to twist our way around the debris to get me back home. After looking at my new pants, I decided to skip supper.

It is now Sunday morning and the storm has subsided, although it is still raining off and on. The electricity and phones are still both out and the Internet and the cable TV both work very intermittently so I don’t know when this message will get off to you; but the (non-renewable) diesel generator here at the AEDB is working (sort of) and I have enough electricity to write this report. I have been reminding the people I work with that the Indus Valley here has had civilization for the past 8000 years and fossil fuels will have been used for only about 250 years before we stop in a couple of decades. So which is the short term alternative, and which is the real sustainable form of energy?

I will be back in Boston on Wednesday evening the 29th of this month, in time to give the PV module assembly workshop at Tufts University before flying off on Wednesday the 5th of August to do the same thing at the University of Nebraska in Omaha. Then on Tuesday the 11th of August I go off to Peru to repeat the same month long cottage PV module assembly and installation workshop up in Ninacaca, 14,500 feet up in the Andes. I’ll be back in Maine by the 9th of September if everything goes as planned.