Nanosolar Goes Live

I have been watching a company called Nanosolar for some time now. They came up with a novel and disruptive technology for producing photovoltaic (solar electric, PV) panels.

The usual method for making PV panels is to grow crystals of purified silicon and shape them into cells. Some companies grow big sausage shaped crystals and saw them into discs, like high-tech pepperoni. Others grow them in thin sheets or hollow octagonal tubes. All these methods require melting silicon (sand, essentially), growing the crystals, and then treating them with minute quantities of chemicals to make them photoreactive. It all takes a lot of energy and time.

Nanosolar’s innovation is to make a nanomolecular ink. That is, a fluid that has sub-microscopic particles in it. It is made up of copper, indium, gallium, and selenium, hence the acronym CIGS. They spray this ink on metal foil from a roll and voila, instant solar material at room temperature. The ink film is extremely thin, so very little of the rare elements gets used. The foil is cut into cells and those cells are sandwiched between two sheets of tempered glass to make a module.

They just fired up a highly robotic factory in Germany with a capability of 640 megawatts a year. Compare that to perhaps 150 megawatts of annual production in the U.S. right now. The video of the factory is entertaining, awkward engineer talking heads aside.



Those of you not in the solar business can go get a doughnut or something, because I am going to write about specifications for a bit. Nanosolar doesn’t give dimensions in its promotional material, but from the photos the module appears to be about one meter by a little over two. They specify a power range of 160 to 220 watts at 6 amps, so the operating voltage is roughly that of a standard 24 volt module, 26 to 36 volts. They say that they sort and bin the cells by voltage off the line, so it seems that they have a slightly broader than voltage spread than is usual for crystalline silicon cells. They claim a cell efficiency in the mid-teens, but given my size estimate the functional module efficiency works out around 10%. The modules dispense with the usual deep aluminum frame and rely on the sandwich of tempered glass for strength. This bodes well for longevity. The only other module out there with double glass is the ASE-300, which seems to have a very low rate of degradation. Much of the deterioration I have seen in conventional modules has been related to the failure of the plastic back sheet.

The ultimate point of these modules is the potential for low energy, low cost manufacturing. Nanosolar has hinted at a cost of a dollar a watt, the Holy Grail of the PV industry. Looking at their methods and product, I can believe it. Such a price would reduce the raw cost of residential solar to the range of $4.50 to $5.00 a watt. That translates into a per kilowatt-hour price of around 15 cents, in the range of what a lot of Americans are paying now. Subtract the 30% federal tax credit and the amortized price per kilowatt-hour drops to around 11 cents. In Vermont, with its $1.75 a watt cash incentive, it would make residential PV a no-brainer at 5 cents. (I’m not even considering Vermont’s Act 45 feed-in tariff.) That kind of pricing is the disruptive factor.

Don’t expect to see these modules on your neighbor’s house any time soon, though. Nanosolar has pursued a policy of megawatt-scale sales to major installers for industrial arrays. It’s a smart move in terms of controlling the rollout of their product and minimizing sales effort and customer service costs. I understand the reasoning, but I still wish I could get my hands on a few.